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Byte, septiembre del 85. Diez años de Byte

Portada de Byte de septiembre de 1985. Un tema de portada es el 'homebrewing', el otro, el supersistema de Ciarcia, con un ordenador compatible con Z80 a 6 megahercios y con 256 kilobytes de RAM

Pues vamos allá con el número de septiembre del 85 de Byte, el del décimo aniversario de la revista… En portada, un ordenador, pero uno construido por uno de los autores estrella de la revista, Steve Ciarcia, que se sacaba de la manga un ordenador de 8 bits para la era de los 16, con todo lujo de esquemas para que te lo montaras tú mismo:

BUILD THE SB180 SINGLE-BOARD COMPUTER

PART 1: THE HARDWARE

by Steve Ciarcia

This computer reasserts 8-bit computing in a 16-bit world

Newer, faster, better. These words are screamed at you in ads and reviews of virtually every new computer that comes to market. Unfortunately, many of the proponents of this rhetoric are going on hearsay evidence. While advertising hype has its place in our culture, a more thorough investigation may lead you to alternative conclusions.

Generally speaking, quotes of increased performance are basically comparisons of CPU (central processing unit) instruction times rarely involving the operating system. The 68000 is indeed a more capable processor than the 6502, but that doesn't necessarily mean that commercial application programs always run faster because the CPU has more capability. People owning 128K-byte Macintoshes have discovered this.

The bus size of the processor is only one factor in the performance of a computer system. Operating-system design and programming styles contribute much more to the overall throughput of a computer. It is not enough to simply compare 8 to 16 bits or 16 to 32 bits. For example, the Sieve of Eratosthenes prime-number benchmark runs faster in BASIC on the 8-bit 8052-based controller board presented in last month's

Circuit Cellar than it does on a 16-bit IBM PC.

Y por si esto no fuera suficiente para la sección «cosas que no veríamos en una revista generalista de informática hoy»…

AN ANALYSIS OF SORTS

by Jonathan Amsterdam

How to choose one sorting algorithm over another

A friend told me recently that 90 percent of all the computer programs in the world sort. I can believe it. Our society's passion for organization has elevated the simple task of putting things in order to a position of major importance. And who better to carry out the job than those informational beasts of burden— computers?

Because of their significance, sorting algorithms have been thoroughly studied. Some are slow and some are fast. Some sort a few items and some sort millions of items. Here I want to discuss sorting in the context of three different algorithms: Selection Sort, for small lists. Quicksort, for larger lists, and Mergesort, for lists of a size so monstrous they can't fit into memory all at once. But first we will need to develop some simple tools to help us with our analysis of these algorithms.

Analysis

Our goal is to understand the efficiency of some sorting algorithms. But we are immediately faced with a problem: How can we study an algorithm in the abstract without considering the language it's written in or the machine it's running on? For example, any algorithm written in a high-level language will run faster when written in

assembly language. And any program running on a microcomputer would run faster on a mainframe. We want to abstract away from these facts, to talk about an algorithm's running time independent of machine or language.

Efectivamente: una discusión lo suficientemente sesuda como para una asignatura de Algoritmos de primero de carrera sobre los diferentes algoritmos de ordenación (temazo de lectura siempre muy recomendable), con sus grafiquitas sobre complejidades de tipo lineal, cuadrática y «n log n», algoritmos no tan básicos…

Figure 1: the rates of grouth of n, n log n and n squared

Listing 1: The algorithm for Selection Sort.

Selection Sort.

Input: an array, A, and its size, n.
Output: the same array A, in sorted order,
begin for i : = 1 to n do begin
m : = i;
for j : = i + 1 to n do
compare A[j] to A[m], making j the new m if it is less;
swap A[i] and A[mj;
end
end.

…el merge sort (o ordenamiento por mezcla),

Figure 2. The mergesort treeListing 2. The algorithm for Mergesort.

Mergesort.

Input: a list, L.
Output: a sorted list, S.
begin
If L is one item long, then S = L
Otherwise, split L into two lists L1 and L2, each about half as big.
Mergesort L1 into S1.
Mergesort L2 into S2.
merge S1 and S2 into S.
end.

…o el mismísimo Quicksort:

Listing 3: The algorithm for Quicksort.

Quicksort.

Input: an array A, with items from 1 to n.
Output; the same array, sorted,
begin
choose a pivot;
partition the list so that all items < = pivot are < i;
Quicksort A from 1 to i - 1 ;
Quicksort A from i to n;
end.

Pero la gracia de este número era la celebración del primer decenio de vida de la revista, y el consiguiente echar la vista atrás, entrevistas incluidas con el ya citado Ciarcia o Jerry Pournelle (de quin hablamos en el número de julio).

NO CELEBRATION of BYTE's 10th anniversary would be complete without the acknowledgment of some of the events and contributions that helped to shape the magazine. In the too-few pages that follow, we tried to capture some of the flavor of the past 10 years.

Special thanks to all contributors and to the BYTE staff, especially Gregg Williams, who chaired the project, Richard Shuford, Rich Malloy, Mark Welch, and Stan Wszola.

A Microcomputing Timeline
Notable Quotes
Evolution of the Microprocessor
Interview: Carl Helmers
Interview: Steve Ciarcia
Ciarcia's Prodigious Output
Interview: Robert Tinney
Tinney Favorites
Interview: Jerry Pournelle

Vale la pena ir siguiendo los enlaces a la revista que dejo en cada imagen, aunque solo sea para disfrutar de las maravillas del diseño industrial de la segunda mitad de la década de los setenta y la primera mitad de la de los ochenta…

Fotos de los ordenadores Sphere 1, Kim-1 y el Altair 8800, todos ellos de de 1975

…como el Sphere 1, el Kim-1 o el mitiquísimo Altair 8800 por ejemplo.

Recuperando temas que a veces no recordamos que vienen de muy lejos, los teclados:

Que el Keyport 717 tiene bien poco que envidiarle al más loco de los teclados actuales.

En la Kernel del mes nos encontramos con el lanzamiento de Excel en una conferencia conjunta de Microsoft y Apple porque, como igual no sabías, Excel era originalmente una aplicación para el Mac.

Kernel

The ongoing construction work at Chaos Manor made it desirable for Jerry to escape yet again. He attended a joint press conference held by Microsoft and Apple in New York. The product introduced at the conference, Excel, is a spreadsheet for the Macintosh. Comments made at the press conference caused Jerry to put down some thoughts on software integration and whether or not we need it. He also looked at several new products, including a new version of BASIC from the inventors of the language.

This being our anniversary issue, Dick Pountain brings us a condensed history of personal computing in Great Britain. He also introduces us to a rugged new lap-held portable, the Husky Hunter.

From Japan, Bill Raike sends us an abbreviated history of that country's microcomputers and also discusses an innovative new product from Brother Industries— the SV-2000 Software Vending System.

In this month's According to Webster, Bruce describes his experiences at the West Coast Computer Faire. He discovered that it isn't as much fun as it used to be, but he found some interesting products on display. He also discusses Apple's plans for the Macintosh, predicts success for the Amiga, and looks forward to testing a host of new products.

Bob Kurosaka discusses the world of transcendental numbers in Mathematical Recreations. Some of them are familiar to us, such as e, the base of natural logarithms, and ir. He looks at some hiding places for these two numbers and some ways to approximate their values.

Y no podíamos saltarnos, claro está, sobre el textito que le dedica Pournelle al Amiga, por el que vota como sucesor del Apple II a finales de los ochenta. Ojalá, Jerry. Ojalá.

Amiga

Among its other faults, Apple has been shamelessly neglecting the Apple II family, and specifically the Apple IIe. When the IIc came out a year ago, Apple cut the price of the IIe and slowed production, figuring the machine would die of its own accord. Instead, the sales jumped dramatically, easily outselling the IIe. People would see the IIc ads, come into the computer store, and walk out with a IIe. Why? Because the IIe had slots, while the IIc (like the Mac) was a closed machine. The IIe is a chameleon: With the right set of boards, you can make it look like and do just about anything. Case in point: The nicest development system I've ever used, including mainframes and minis, was an Apple IIe with 128K bytes of RAM, an AcceleratorIIe card (3.5-megahertz 65C02), and two Axlon 320K-byte RAM disks (configured as four 160K-byte floppy disks). Apple's response to the increased IIe sales was to cut back on production and raise its price (while discounting the IIc). Even so, it wasn't until late 1984 that the IIc finally started outselling the IIe.

What does this have to do with the Amiga? Well, several machines are competing in the low-end market: the Atari 520ST the Apple IIe, the Mac (to a lesser extent), and the Amiga. Guess how many of these are easily expandable? Just one: the Amiga. Guess which machine will probably end up being the Apple II of the late eighties? I don't think the IIe will, nor the Mac, and the ST is a tightly closed, nonexpandable box. My vote is for the Amiga. From what I can see, the Amiga's graphics, sound, 68000 processor, memory map (allowing up to 8 megabytes of RAM), and expansion bus give it the potential of a long and successful life. There's always the chance that Apple will, indeed, come out with a souped-up Apple II next year, but even with the Western Design Center chips (65816. etc.) and the nifty 3 /2-inch Duodisk (1.6 megabytes of storage), it will probably be too little, too late. — (Dejo la imagen enlazada a la versión grande de la imagen, y no a la fuente en el Archive (aunque siempre tenéis la opción de leer el texto alternativo de la imagen).)

Y cierro con dos piezas más. La primera, lo normal en las revistas actuales (no): el típico artículo de dedicado a los números π y e…

pi, e, and All That

Sneaking up on transcendental numbers

by Robert T. Kurosaka

God made integers, all else is the work of man.
— Kronecker

This famous quote of Leopold Kronecker serves as the starting point for this month's column. The integers (the whole numbers) can be used to construct other numbers.

We can construct rational numbers by dividing one integer by another. When we do so, we get either a terminating decimal (1/4=0.25) or a nonterminating, repeating decimal (7/18 = 0.388888 ...). Repeating, or cyclic, decimals are a fascinating study I may explore in a future column.

Irrational Numbers

We can also construct numbers that are both nonterminating and nonrepeating. It is a rather amazing notion that a string of digits may go on forever without having to establish a pattern. It's such an odd notion that the ancient Greeks originally did not believe it possible— or even imaginable. When it was established that the square root of 2 was such a number, the Greeks called this kind of number irrational. The root meaning of irrational is "without ratio,'' or unable to be expressed as a fraction. The Greeks found such numbers irrational not only in the sense of "non-ratio-able" but also in the sense of "nonsensical."

The differences between rational and irrational numbers are substantial. It can be shown that no more rational numbers exist than do whole numbers, but irrational numbers outnumber rational numbers. This fact, which is often presented as a paradox, is not especially surprising when you look at how we have constructed rational numbers. They are built up out of whole numbers and can be expressed as integer fractions. As I said above, irrational numbers cannot be so expressed.

TWO TYPES

There are two different kinds of irrational numbers. The first, like the square root of...

…y el segundo dedicado al Versabraille II, un ordenador diseñado para funcionar usando braille, porque la preocupación por la accesibilidad tampoco es nueva:

VersaBraille II

Telesensory Systems has introduced the VersaBraille II system, a portable, disk-based electronic information processor for the blind. This braille computer lets you electronically store, process, and retrieve information. A special telephone modem can link VersaBraille II to other computers.

VersaBraille II consists of a standard 3 '/2-inch microfloppy-disk system and a braille display that substitutes for a video monitor. Its memory holds up to 30.000 characters; disk support boosts the unit's capacity to 77,000 characters. This is adequate for many word-processing procedures, such as formatting, high-speed searching, and inserting, deleting, and relocating text. The system can simultaneously output braille and print information.

VersaBraille II is fully programmable. Menus guide the user to each of the system's programs. The manufacturer provides special software that converts VersaBraille II into a four-function calculator with algebraic logic, floating decimal point, square root, and percent. Plans for other software packages include a 50,000word spelling checker, a two-way braille translator. and a language interpreter.

The price of a VersaBraille II system is S6995 plus shipping and handling.

He encontrado poca información sobre el Versabraille II, pero si alguien quiere investigar sobre su antecesor, el Versabraille original, aquí un documento por el que comenzar.

Apa. Volvemos el mes que viene con el número de octubre. Por cierto, que si alguien quiere hacer los deberes por su cuenta, además del archivo de la revista en el Archive, también tenéis esta chulada de navegador que me pasó hermanito hace unas semanas.

¡Hasta la próxima!

Byte, agosto del 85 (y el lanzamiento del Amiga)

Decíamos «ayer» que el número de agosto de la revista Byte (de 1985, porque en esta casa siempre hemos ido con un cierto retraso 😬, especialmente en este miniproyecto nuestro de repasar la «actualidad» de la informática a través de la revista) venía interesante. Y no mentíamos:

Portada de la revista Byte de agosto de 1985. Se ve el cuadro Jeune fille dessinant dans un interieur, de Picasso, y una reproducción del mismo en la pantalla de un ordenador Amiga 1000. El otro tema de portada son los lenguajes declarativos, de entre los que se destacan Prolog, Hope y FP — Sí, es un Picasso. De la colección del MoMA. Si queréis el título, siempre podéis hacer una búsqueda de imágenes… o acceder al texto alternativo de esta captura.

El Amiga 1000. Probablemente, mi ordenador favorito. En la portada de la revista Byte.

Debe decirse, primero, que en aquella época no era exactamente habitual tener un ordenador en la portada. Antes del Amiga, el PC de IBM en el número de enero del 82 y el Lisa (acompañado del Apple IIe) en el de febrero del 83, y muy, muy pocos otros: un par de Compaqs justo antes del Lisa, en enero del 83, el HP-150, un fallido intento de ordenador personal MS-DOS de Hewlett Packard (¡con pantalla táctil!), en octubre del 83, el Mac en febrero del 84, y el Data General/One en noviembre del 84. Y después del Amiga, llegarían el PC UNIX de AT&T en mayo del 85, el Atari ST en marzo del 86, el Macintosh II en abril del 87 y el Personal System/2 de IBM en junio del mismo 87. Vamos, que tres al año como mucho.

(También podríamos destacar la puntería de la revista en seleccionar ordenadores de poco recorrido comercial, pero no vamos a hacernos daño…)

The AMIGA Personal Compuer

Its speed and colorful graphics come from a 68000 and sophisticated custom chips

There are two ways to get works done inside a computer: do it in software or do it in hardware. The first way gives you unlimited flexibility; the other, speed. The Apple Macintosh does almost everything in sofware—and...

Si seguimos leyendo, nos encontramos con cosas como

Por 1295 dólares, el Amiga promete gráficos de metáfora de escritorio a color y rápidos como un relámpago, con el doble de memoria y disco que el Macintosh por cientos de dólares menos.

También destaca el artículo la arquitectura del Amiga, con sus tres chips especializados (Paula, Denise y Agnes, diseñados por el legendario Jay Miner), conectados por buses de una velocidad inaudita en la época, el copper y el blitter de Agnes y sus capacidades gráficas (que alguien se haya tomado la molestia de replicar la documentación del sistema operativo en su versión de 1993 es un indicativo más del amor que despertaba y sigue despertando el Amiga), hasta 4096 colores en pantalla de una paleta de 24 bits (el primer Mac en color, el Mac II, salió en el 87, por algo más de 3700 dólares), y el multiproceso real con el que el resto de ordenadores personales de la época no podían ni soñar en 1985 (tanto es así, que el artículo dedica algún párrafo a explicar qué es la multitarea). Y también se fijan, claro, en que el sistema operativo ofrecía a las aplicaciones el uso de bibliotecas de funciones, otro aspecto tremendamente innovador por aquel entonces. Un sistema operativo elegante para un hardware igualmente distinguido.

(Merece también especial mención el nivel de detalle técnico al que entraban las revistas de la época, como ya hemos comentado alguna vez por aquí. En serio, haced clic en la captura del artículo para acceder a la revista y echadle una ojeada.)

Como es el Amiga, no puedo irme sin dejar un par de vídeos de «contenido complementario». Por un lado, este repaso a la máquina…

Y por esto, aprovechando que, obviamente, el Amiga acaba de cumplir cuarenta años, este vídeo de la celebración del cumpleaños.

En el vídeo encontraréis todo tipo de historias y batallitas del desarrollo, incluyendo el primer anuncio en el CES de enero del 84 (hay un universo paralelo en que la escena del CES de Halt and Catch Fire está protagonizada por esta gente… y seguramente el mundo de la tecnología es un poco menos tóxico que en nuestro universo).

El segundo vídeo, por cierto, sale de una noticia en Tom’s Hardware sobre el tema y el avistamiento del prototipo que se mostró en el CES (quién fuese rico para ofrecer una pasta por él).

Volviendo a la revista, unas páginas más adelante nos encontramos con un anuncio del otro ordenador nuevo de Commodore, el 128:

Anuncio del Commodore 128. Vemos una foto del Commodore 128, con un monitor, una disquetera de 5¼ y un teléfono. El texto habla de la capacidad del 128 de ejecutar software del Commodore 64 y CP/M

El 128 había sido anunciado en el número de febrero, y uno diría que la duplicidad 128 / Amiga era señal de la mala gestión de la cartera de productos de Commodore… pero Apple hacía lo mismo con el Apple II y el Mac.

Un poco más adelante nos encontramos con lo que eran los PCs de la época. Las comparaciones, efectivamente, son odiosas…. pero seguimos en un mundo Wintel (y cada vez más Mac, ciertamente). Mil dólares por el ordenador con 128 kBs de RAM y una disquetera (de discos de 360 kBs)…

System Review

The Tandy 1000

When I first heard about the Tandy 1000, I was quite impressed. It seemed to have almost everything I would want in an IBM Personal Computer clone. Plus, it had some of the better features of the PCjr.

For those who haven't seen this machine yet, the Tandy 1000's features include one 360K-byte disk drive (expandable to two, plus one 15-megabyte hard-disk drive), 128K bytes of memory (expandable to 640K bytes), a parallel printer port, interfaces for composite monochrome and RGB (red-green-blue) monitors and a light pen, graphics and sound similar to those of the PCjr, joystick ports, three IBM-compatible expansion slots, a general-purpose collection of software (DeskMate), and a fairly good price ($999). Even a full BYTE configuration (two floppy drives, 256K bytes of memory, monochrome monitor, and serial port) has a reasonable cost ($1746), considering that you get some free software bundled with it.

Description

Since BYTE has published a product description of the Tandy 1000 (see "The Tandy 1000" by G. Michael Vose, December 1984, page 98), I will skip most of the details. Suffice it to say that the system Tandy sent me (two drives, 256K bytes of memory. RGB monitor) fits nicely on my desk and has attracted quite a bit of attention (see photo 1). The system's fan is quieter than that in my IBM PC. and I doubt it will be a disturbance in the office or the home. I have left it on for long periods without noticing it.

The disk drives follow the Tandy tradition of putting the primary A drive below the optional B drive. And while the disk drive latches do not have that feel of quality I have noticed on other machines, the disk drives themselves are fairly quiet and seem to work well.

The machine's general design is logical. The on/off switch is on the far end of the right side of the machine (just like IBM), but

many other items are on the front where they are accessible. These include the keyboard and joystick connectors and a red reset button. You access the expansion-board slots through the front as well.

Keyboard

Tandy seems to know how to design keyboards. Apparently recognizing a good thing when they see it, Tandy's designers reissued the Tandy 2000 keyboard with hardly a key label changed. The Tandy 1000 keyboard (see photo 2) has the same layout, the same superior feel, and the same welcome relief from the standard clone keyboards that keep appearing on the market. Some of its better features are a separate inverted-T cursor-key layout, a left Shift key and carriage return in the places where you would expect them, indicator lights for the Caps and Num Lock keys, 12 function keys arranged horizontally, and a Hold key. In short, it is one of the better keyboards on the market.

The only aspect of it I don't like is that the function keys are too close to the numeric keys. For example, I sometimes hit the 5 key when I mean to hit F5. Also, if you are accustomed to IBM's vertical function keys, the horizontal arrangement can be confusing. And since some of the keys have different key codes than those on the IBM PC. you might find that in a small number of programs these keys do not work as they should. For example, the XyWrite II Plus word processor does not recognize the Tandy's cursor keys. It looks to the numeric keypad, as on the IBM PC. Fortunately, XyWrite II Plus lets you reconfigure the keyboard as you wish.

Y nos vamos con tres breves. Primero… no, lo de volvernos locos por los editores de texto, tampoco es nuevo. Dentro de la sección Kernel de Jerry Pournelle nos encontramos con EMACS (y Richard Stallman):

Yet Another EMACS

Another minibooth featured EM-it, an EMACS imitator. EMACS is the macro editor written at MIT by Richard M. Stallman (otherwise known as RMS). EMACS was one of the very first full-screen editors in existence. I recall several long-distance debates (I have an account on one of MIT's large computers) with RMS over the virtues of EMACS versus Electric Pencil, which was the editor I was using at the time. The debates were futile, of course: Pencil and WRITE (derived from Pencil) were much better editors for creative writing, but EMACS was far and away better for programming, and indeed it became a bit of a legend among hackers.

Stallman, who believes software ought to be available to everyone, put EMACS in the public domain instead of getting rich from it. The chaps at Sayansi have implemented it for PCompatibles and sell their version for $49.95, a reasonable price. Needless to say, it's not copy-protected. It's also not full EMACS. One of the main features of EMACS is its extensibility: you can add nearly any feature you might want from right inside the editor. EM-it can't do that, but it does...

Si seguimos avanzando, nos encontramos con el mítico Amstrad CPC6128 y sus discos (que ya no recordaba yo)… ¡de 3 pulgadas! Otra colección de máquinas, la de Amstrad, que merecía mucho más éxito comercial del que tuvo.

Y más adelante aún, como es natural, este paquete de IA y Forth… ¡para el Commodore 64!

Programming Environment with AI Module

Superforth 64 + AI, an integrated package for the Commodore 64, is a programming environment that includes an artificial intelligence module and advanced math capabilities. The package is designed to help you develop expert systems.

At Superforth's core is a programming language that lets you define your own English-like "word" functions. These words are stacked to create rules; an interpreter then applies the rules to make decisions. Antecedent and consequent reasoning are possible.

The program incorporates the utilities needed to write applications, including full control of color graphics; sound, music, and sprite editors; trace and decompiler facilities; and virtual memory. Superforth 64 + AI sells for $99.

Y el último, considerad que este anuncio de la propia revista pretendía dar una imagen atractiva y moderna del informático de la época:

En el anuncio de Byte, el informático es un señor de americana y corbata con una prominentísima calva.

En fin. Lo dejamos aquí. En otra ocasión le habría dedicado un tiempo a los artículos sobre Prolog, la programación lógica (firmado por Robert Kowalski), o los lenguajes declarativos (cofirmado por Susan Eisenbach, manía tienen los autores de Byte de la época de acabar en la Wikipedia), entre otros, que componían el otro tema de portada de la revista, pero me temo que este mes gana el Amiga…

Si no pasa nada, volvemos el mes que viene. Si tenéis curiosidad por seguir leyendo, aquí tenéis el número de agosto del 85, y también el archivo completo de la revista en Archive, por si queréis avanzar tarea. ¡Hasta la próxima!

Byte, julio del 85

Seguimos con nuestro proyecto de hojear, con un delay de cuarenta años, la revista Byte. Este mes el tema de portada es el espacio y la informática y no vamos a encontrar joyas especialmente interesantes… (El número de agosto será mucho más interesante, puedo prometerlo.)

La portada de la revista Byte de julio de 1985. La imagen de portada en un enorme disquete de cinco pulgada y cuarto. El tema de la revista es Ordenadores y espacio

En las noticias tenemos que comienzan a llegar los sistemas con procesadores 286 (en el número de mayo habían comentado la llegada del IBM PC AT):

New 80286 Systems Flood COMDEX

Late spring saw the introduction of many new IBM PC AT-compatible computers. By mid-May, new 80286-based systems had been announced by Kaypro, ITT, Compaq, TeleVideo, Corona, Texas Instruments, Zenith, NCR, Tomcat, and Basic Time. Another multiuser AT compatible computer, available from MAD Computer in both floor and desktop models, will be sold only to other manufacturers. Wang also disclosed that it is developing an AT-compatible system.

Intertec, West Columbia, SC, has redesigned its HeadStart computer, replacing its 8086 processor with an 80286 and eliminating its 3½ inch disk drive. The HeadStart ATS's standard 256K bytes of RAM can be expanded to 3 megabytes; the computer also includes serial, parallel, and network interfaces. The basic HeadStart ATS is priced at $1895 without disk drives. A dual 5 '/4-inch disk-drive add-on unit is $495 extra. Intertec also announced several 80186-based file servers for its MultiLAN proprietary polling network; a $695 interface card also allows IBM PCs to be attached to the network.

Mientras quede «contenido Commodore», lo seguiremos recogiendo por aquí, esto es un hecho:

Anuncio a doble página del Commodore 128 en el que explica todas las cosas que habría que añdir a un Apple IIc para conseguir la potencia de un Commodore 128, como las capacidades de sonido.

¿No os recuerda un poco al dichoso anuncio de hace unos meses de Apple en que aplastaban todo tipo de herramientas creativas? Igual es que Apple estaba recuperando el trauma de este anuncio anti-Apple de hace apenas cuatro décadas…

En la sección de libros nos encontramos otro tema recurrente: la accesibilidad.

PERSONAL COMPUTERS AND SPECIAL NEEDS
Reviewed by John Wilke

In 1977, a group of activists with a variety of disabilities staged a symbolic sit-in at the Department of Health, Education, and Welfare to demonstrate support for a bill frequently called "the civil rights act for the disabled."

Since that legislation became law, engineers and city planners must design public buildings that are accessible to all people. The young man who led the HEW demonstration and lobbied successfully for the new law has turned his attention to overcoming another set of barriers: software, computers, and communications equipment that, by design, shut out the disabled.

Frank G. Bowe is quick to point out in Personal Computers and Special Needs that just as new technology is beginning to make it possible for disabled individuals to not only communicate more effectively but also pursue meaningful employment in the information industry, there is a lack of physically compatible and affordable computer interfaces. This paradox is an underlying theme in Bowe's book, a survey of personal computer peripherals and communications prostheses available to people whose hearing or vision is impaired or who are unable to manage normal movement.

Bowe takes what might have been little more than a listing of the latest in speech synthesizers and keyboard emulators and peoples it with firsthand accounts of how the devices are making life more productive for disabled people. Unifying this effort is his concern that with the transition to an increasingly information-based economy— with its obvious promise of fuller participation for the disabled—the danger remains that a new set of barriers will prevent them from participating.

The book, then, addresses both how-to and why. It was written first for the nearly 30 million Americans who might...

El comentario de siempre: hace más de cuarenta años que unos cuantos se interesan por el potencial de las tecnologías digitales para ponerlo todo al alcance de las personas con discapacidad… y el resto que no le presta ni la más mínima atención al tema. El libro, (Personal Computers and Special Needs) por cierto, está disponible en archive.org.

En el número de marzo habíamos hablado de pantallas planas que usaban paneles de plasma y pantallas electroluminiscentes, las tecnologías que hoy sabemos que no iban a tener éxito. Ahora llegamos a los LCDs:

(Por cierto, si os atrevéis a seguir el enlace (cada escaneado está enlazado a la página correspondiente de la revista en Archive), sabed que os vais a encontrar una discusión bastante técnica de la tecnología LCD.)

Y llegamos al tema de portada:

COMET LINES IN FORTRAN

by David S. Dixon

The program described calculates the positions of asteroids and comets

THE PROGRAM DISCUSSED in this article is intended to allow amateur astronomers to calculate the positions of asteroids or comets with greater accuracy than the programs previously published in general literature. Written in FORTRAN IV, the program should be translatable to any BASIC that supports double-precision calculation. But be advised that this is a number-crunching program: it may run for hours if rewritten in interpreted BASIC

Asteroids are a very challenging target for the observer: they appear as points of light just like the stars. Depending on the asteroid's position relative to earth, it may or may not demonstrate detectable motion against the background stars. Frequently, several nights of observation are required to see displacement and identify the asteroid. Successfully hunting a particular asteroid usually means having a good idea of the asteroid's position at the intended time of observation and having a good set of star charts.

The problem is that accurate tables of locations for asteroids, known as ephemerides, are not easy to come by. The United States Naval Obser-

vatory publishes ephemerides for the four major asteroids in The Astronomical Almanac each year, but there are thousands of named asteroids. (For a list of books and periodicals mentioned in this and other articles, see the 'Astronomy Sources" text box on page 244.) The Soviet Union's Institute of Theoretical Astronomy publishes the Ephemerides of Minor Planets, which gives ephemerides for thousands of asteroids, but only for a few weeks at opposition, and it is a difficult publication to obtain. Both the Russian and the Naval Observatory publications, however, also give the orbital elements for a large number of asteroids, and with the elements it is possible to calculate the ephemerides of an asteroid yourself.

Many of the books and magazine articles that address calculating the position of a planet solve the problem by the model devised by Johannes Kepler in 1609. The method models the motion of a body in the solar system as involving only the sun and the body in question. This means that to find the relative positions of Earth and Mars in a common coordinate system you solve the two-body sun-Mars problem, solve the two-body sun-

Earth problem, and, using spherical trigonometry, combine the two results to solve the Earth-Mars problem. The method can produce results satisfactory for use in finding planets, but the accuracy for use on asteroids is frequently inadequate. Kepler's model is a remarkable achievement since he derived it by geometry as an empirical solution based on position measurements made by lycho Brahe. Kepler's model is summarized in his first two laws:

First law: The orbit of each planet is an ellipse, with the sun at one of the two foci.

Second haw: The line joining the planet to the sun sweeps over equal areas of the ellipse in equal intervals of time.

It was not until more than 50 years after Kepler's work was published that the work of Sir Isaac Newton explained the process that Kepler's model described and how the model was incomplete. Newton's law of gravi

Imagino que no sorprenderá a ningún lector habitual de obm encontrarse a un ingeniero de la NASA describiendo un programa en FORTRAN IV (yo hice mis pinitos con FORTRAN 77 unos pocos años más tarde) para trazar órbitas de asteroides y cometas. Lo mismito que ahora.

FORTRAN 77, por cierto, se lanzó en 1978, el IV es de 1961, y no me tiréis de la lengua con lo de la evolución del software y el uso de un lenguaje de más de veinte años de edad en el artículo. (Rascando un poco por la Wikipedia, compruebo que Fortran (perdió las mayúsculas en la versión 90 que, como adivinaréis, es de 1991) está ahora mismo el 12 en el TIOBE, un ranquin de uso de lenguajes de programación.)

Unas páginas más allá encontraréis un programa de seguimiento de satélites, y a continuación otro artículo sobre el control de telescopios. Y en la página 265, la crítica de una aplicación para seguir el cometa Halley, que pasaría por el sistema solar en 1986 (se le espera de nuevo a principios de 2061).

Y aprovecho que el número tenía poca «chicha» para detenerme en una de las columnas más míticas del periodismo sobre informática, el Computing at Chaos Manor de Jerry Pournelle.

Pournelle, fallecido en 2017, se dedicaba a la investigación operativa (con finalidades militares, parece ser), a escribir ciencia ficción (con un par de best sellers escritos a cuatro manos con Larry Niven), y a ser el power user de los power users con su columna, que apareció en la revista desde 1980 hasta 2006. Y en la columna narraba sus aventuras y desventuras con su extensa colección doméstica de ordenadores, que yo me leía (debía entender la cuarta parte, con suerte) con fascinación.

Quien dice «columna» dice «minirevista»: la de este número arrancaba en la página 309 y se iba hasta la 338 (con mucha publicidad de por medio, sí, pero vaya, que es un atracón), seguida de una página de correo de los lectores específica de la sección.

¿El contenido? Comenzamos con una visita a una feria informática que incluyó comer con Niklaus Wirth (ojo a la broma que se le atribuye sobre la pronunciación de su nombre que incluye la pieza). Seguimos con una discusión sobre si el futuro era de Intel y sus 286 y familia o de Motorola y sus 680×0, que se enlaza con una batallita sobre compiladores de Modula-2 (lenguaje creado por… Niklaus Wirth). Y si Wirth no fuese suficiente, luego tenemos una feria sobre el Mac en la que cenó con Frank Herbert. Sí. Ese Frank Herbert (que fallecería en 1986, por cierto). Pournelle iba a comprar un segundo Mac con la intención de ampliarlo a un mega de RAM (la mitad de la cual, dedicada a disco en memoria, que el Mac no podía direccionar más de 512 KBs), por apenas 1500 dólares.No descartamos que en el futuro se cuele alguna batallita «Chaos Manor» más.

En fin. Lo dejamos aquí (ya decía que no fue un número especialmente interesante, el de julio del 85) y recuperamos el mes que viene, mucho más interesante, al menos para mí.

Si alguien quiere entrar más a fondo, aquí está el número de julio entero, y aquí el archivo completo de la revista en Archive.

Byte, junio del 85

Pues nada, seguimos con nuestro proyecto de leernos cada mes la revista Byte… de hace cuarenta años. Y le toca el turno al número de junio de 1985. Encontraréis todos los números en esta colección de archive.org, y el que leemos hoy, en concreto, dedicado a las técnicas de programación.

Portada de la revista Byte de junio de 1985. La imagen de portada es un cubo de Rubik en que cada una de las pequeñas caras del cubo es un una palabre clave informática. Entre ellas, tenemos char, DUP, UNIT, CAT, REM, puts, NULL, GREP, COND, FOR, GOTO...

Tampoco es que sea el número de mi vida, pero tiene sus cosillas. La primera en que me paro tiene que ver con accesibilidad:

Products Will Aid Visually Disabled Computer Users

Computer Aids, Fort Wayne, IN, introduced several microcomputer products for the disabled. One product, Small-Talk, uses a modified Epson HX-20 and a speech synthesizer to allow blind users to perform word-processing tasks. With a printer, microcassette tape drive, and special word-processing software, the computer will cost about $2000.

Que sí. Que hace décadas que hay gente que piensa en usar la informática para ayudar a las personas con discapacidad (en este caso visual). Lástima que tanta otra gente se olvide del tema.

Siguiente parada, anuncio de ordenador de esos que te hace añorar el diseño industrial ochentero:

Anuncio a doble página de la marca apricot. En la página izquierda, los restos de un albaricoque que alguien se acaba de comer, con el texto Past. A la derecha, un albaricoque entero, con el texto Present and Future. En la esquina inferior izquierda de la página, una miniatura de un ordenador de diseño ochentero. Más detalles en la siguiente imagen.

¿Me vais a decir que no es precioso? Bueno. Me vais a decir que no se ve. Hagamos un enhance it:

Zoom de la imagen anterior. Tenemos un portátil en tres piezas. La primera tiene la pantalla (de fósforo verde) y seguramente la CPU. El teclado está en otra pieza, y hay una tercera pieza con lo que parece ser un trackball. La imagen viene con el texto The APricot Portable. 521K RAM, 720K diskette. 80x25 line LCD. MS-DOS. $2495

¿Es o no precioso el Apricot Portable? Había salido a la venta en octubre del 84 y, recomonozcámoslo, le daba sopas con honda a los portátiles de la época (incluido mi adorado SX-64). Ni siete kilos, pesaba. Y las piezas separadas se comunicaban ¡por infrarrojos! ¡El futuro! ¡En 1984! Hasta tenía reconocimiento de voz (aunque habría que poner «reconocimiento» entre toneladas de comillas: dice la Wikipedia que se le podían entrar 4096 palabras, 64 de las cuales simultáneamente en memoria). Y su MS-DOS pasaba de los famosos 640 Ks (para llegar a 768, tampoco nos emocionemos más de la cuenta). En cualquier caso, una preciosidad.

Seguimos avanzando y nos encontramos con otro anuncio:

Anuncio. Vemos la foto de una pantalla de un PC de IBM, con lo que parece una interfaz gráfica del estilo de un Windows antiguo y un programa de dibujo en el que alguien ha creado lo que parece un post it con la palabra hi escrita a mano

¿Qué es eso de GEM? Aquí, otra versión del anuncio:

De nuevo, una pantalla de un IBM PC, con un entorno gráfico de ventanas (también se ve un ratón en la página) y la caja de un software, GEM Desktop, y su precio ($49.95). Se explica que el software era, efectivamente, un entorno gráfico para usar los PCs de IBM sin tener que teclear comandos crípticos.

GEM era el entorno gráfico que desarrolló Digital Research (la compañía de CP/M, fundada en 1974 y que sería adquirida por Novell en 1991 ) principalmente para los Atari ST, pero también para PCs con MS-DOS, entre otros. Y es ver una captura de GEM y que se me caiga la lagrimita. Esnif.

Volviendo a nuestro clásico «¿créias que esto era nuevo?», hoy toca…

Turning a common AI operation into silicon

Logic programming is a staple of artificial-intelligence (AI) software and is often dominated by the pattern-matching process of unification (see the "Resolution and Unification" text box on page 173). In fact, when logic-programming languages such as Prolog and LOGLISP are used, as much as 50 to 60 percent of a computer's processing time is spent on unification. When a single algorithm is used that frequently, it is natural to consider implementing it as custom hardware. When that same algorithm lends itself to parallelism and concurrency because of its recursive, treesearch characteristics, it practically begs for VLSI (very large scale integration) implementation.

SUM History

Professor lohn Oldfield and a team of researchers at Syracuse University are developing the SUM (Syracuse Unification Machine), a coprocessor for computers geared toward AI programming. The project combines the resources of the Syracuse CIS (Computer and Information Science) department. ECE (Electrical and Computer Engineering) department, and the CASE Center (Computer Applications and Software Engineering Center, set up by New York State). Key SUM individuals are Dr. Oldfield himself (who contributed CAD [com-

puter-aided design| and VLSI expertise). Professor Alan Robinson (who is the head of the logic-programming efforts at Syracuse), and Kevin Greene (who made the initial designs of the SUM). Because of a famous 1965 paper, Dr. Robinson is often credited with inventing unification. He is more modest, pointing to the work of Herbrand in the 1930s and the studies of Prawitz and Kenger concerning unification. Dr. Robinson contends that he was just the first to formalize the unification process and apply it to resolution.

In 1981, the Syracuse CIS logic-programming group learned that Caltech (California Institute of Technology) student Sheue-Ling Lien had designed a chip that embodied Dr. Robinson's original unification algorithm (see the "Unification on a Chip" text box, page 1 74). Dr. Robinson and his colleagues were somewhat taken aback that someone else had taken this step. Lien's report was a major inspiration for the development of the SUM, even though the chip it described was never actually made. Because ECE had been developing custom VLSI

chip-design capability and had a strong logic-programming group, combining the pursuits "seemed a natural thing" according to Dr. Oldfield.

Coprocessor Strategy

As Dr. Oldfield explains, "Although we started talking about a unification chip, following along the lines of the Caltech one. it soon became fairly clear that at present levels of integration that was fairly ridiculous. You could make a chip, but it would be limited to solving such small problems that it wouldn't be worthwhile." The SUM group wanted to design a full-blown, practical processor. Besides. Lien's chip used Dr. Robinson's original 1965 algorithm. Much more efficient algorithms have been developed since.

When they realized that a single chip wasn't realistic, the members of the group looked at the possibility of a coprocessor, initially for the LMI

Sí, queridas, podríais pensar que TPUs y NPUs y demás son una cosa acabada de inventar, pero cada vez que la IA se pone de moda, alguien piensa en hardware para acelerarla…

Siguiente cosa que me ha interesado: ¿cómo elegir lenguaje de programación?

CHOOSING A PROGRAMMING
LANGUAGE

by Gary Elfring

It's a three-step process

IF YOU WERE a carpenter building a new house, the first thing you would do would be to collect your tools. The tools you'd select would vary depending on the type of job. The same thing should be true if you are a programmer. You have a wide range of tools available, and you just choose the right tools for the job. Your tools are the languages that you program in and the environments needed to support those languages.

How do you go about selecting the right tool for the job? There are more programming languages available for microprocessors than most people could learn in a lifetime. What you need is a methodology that can be used to select one language from all the rest for a given application.

This article presents a practical method for comparing programming languages. It has an inherent bias toward compiled high-level languages. Compiled languages are faster than interpreted ones, and most interpreted languages also offer a compiler version. Since program speed is often an issue, I chose compilers over interpreters.

The actual process of evaluating a group of programming languages can be broken down into three major steps. The first step is to characterize the application the language is being selected for. Then you must identify the features that a language should have in order to deal with the previously described application. Finally, you should take into account practical considerations to further narrow down the language selection.

The Application

You can't choose a tool unless you know what you intend to do with it. You have to describe your application. Once you have this information you can then proceed to determine whether or not the existing language choices are the right tools for the job. To describe an application, you must consider both the type and size of the application. These questions must be answered before you can proceed any further in the language evaluation:

What is the type or class of application? What level of language is needed?

There are a number of different classes of program applications. An application can belong to a single class or several. Identifying the class of your application is relatively simple and helps narrow the list of acceptable languages. Some of the more common classes include scientific, business, and system programming; text processing; expert systems; and real-time control.

Most programming languages are better suited to solving one particular class of problem than another. COBOL is one example. While it is easy to write maintainable business programs with COBOL, no one would expect to use this language to solve real-time control problems.

Another consideration is the level of programming that the application will require. If you need low-level control of various machine-dependent features, then a very high level language...

La cosa comienza dando preferencia a compilados sobre interpretados por temas de velocidad (cosa más importante hace cuarenta años que ahora, que les pregunten a JavaScript y Python). Sigue proponiendo que el tipo de programa es muy importante (y dando COBOL como ejemplo de lenguaje para aplicaciones de negocios), y a continuación proponiendo si lenguajes de alto o bajo nivel… Comencé a leer el artículo pensando que lo que dijese sería siendo bastante actual. Curiosamente, donde uno esperaba más estabilidad… va a ser que no. Pero claro, entonces llega este artículo sobre componentes reutilizables:

SOFTWARE-ICs

by Lamar Ledbetter and Brad Cox

A plan for building reusable software components

THE SOFTWARE WORLD has run headlong into the Software Crisis—ambitious software projects are hard to manage, too expensive, of mediocre quality, and hard to schedule reliably. Moreover, all too often, software delivers a solution that doesn't meet the customers' needs. After delivery, if not before, changing requirements mean that systems must be modified.

We must build systems in a radically different way if we are going to satisfy tomorrow's quantity and quality demands. We must learn to build systems that can withstand change.

Some system developers are already building software much faster and of better quality than last year. Not only that, the systems are much more tolerant of change than ever before, as a result of an old technology called message/object programming. This technology, made commercially viable because of the cost/performance trends in hardware, holds the key to a long-awaited dream— software reusability. A new industry is developing to support the design, development, distribution, and support of reusable Software-ICs (integrated circuits). A forthcoming series in UNIX/World will address message/object programming.

Message/Object Programming and software-ICs

In this article we'll look at the concepts of message/object programming and how they support the building of "Software-ICs," as we call them, by satisfying the requirements for reusability.

A Software-lC is a reusable software component. It is a software packaging concept that combines aspects of subroutine libraries and UNIX filter programs. A Software-IC is a standard binary file produced by compiling a C program generated by Objective-C.

The notion of objects that communicate by messages is the foundation of message/object programming and fundamental to Software-ICs. An object includes data, a collection of procedures (methods) that can access that data directly, and a selection mechanism whereby a message is translated into a call to one of these procedures. You can request objects to do things by sending them a message.

Sending a message to an object is exactly like calling a function to operate on a data structure, with one crucial difference: Function calls specify not what should be accomplished but how. The function name identifies specific code to be executed. Messages, by contrast, specify what you want an object to do and leave it up to the object to decide how.

Requirements for Reusability

Only a few years ago, hardware designers built hardware much as we build software today. They assembled custom circuits from individual electrical components (transistors, resistors, capacitors, and so on), just as we build functions out of low-level components of programming languages (assignment statements, conditional statements, function calls, and so on). Massive reusability of hardware designs wasn't possible until a packaging technology evolved that could make the hardware environment of a chip (the circuit board and adjoining electrical components)...

Ojo a los dos primeros párrafos:

El mundo del software ha chocado con la Crisis del Software: los proyectos ambiciosos son difíciles de gestionar, demasiado caros, de calidad mediocre y difíciles de programar con fiabilidad. Además, con demasiada frecuencia, el software ofrece una solución que no satisface las necesidades de los clientes. Tras la entrega, o incluso antes, los cambios en los requisitos obligan a modificar los sistemas.

Debemos construir sistemas de una forma radicalmente diferente si queremos satisfacer las demandas futuras de cantidad y calidad. Debemos aprender a construir sistemas que resistan el cambio.

¿Escritos en 1985? ¿1995? ¿2025? ¿Nos jugamos algo a que los podremos reutilizar sin tocar una coma en 2065?

En fin… Si queréis saltar de este mes de junio del 85 a nuestra relectura del número de mayo, aquí lo teneís. y el mes que viene, más (espero).

Byte, mayo del 85

Seguimos leyendo la revista Byte, pero cuarenta años tarde (todas las entradas disponibles en la etiqueta Byte). Si queréis pasar de mis extractos y acudir a la fuente, tenéis todo el histórico en archive.org y el número del mes aquí.

Este mes la cosa sera (relativamente breve). La portada, no especialmente destacable:

Portada de la revista Byte de abril de 1985, dedicada al PC Unix de AT&T

De las noticias, me quedo con un breve. ¿Sabíais que este mes se cumplen cuarenta años del anuncio de Excel? ¿Sabíais que Microsoft lo lanzó inicialmente para el Mac? Pues sí…

Integrated Software for Macintosh

Microsoft's first integrated package. Excel for the Macintosh, has spreadsheet and graphics capabilities, a spreadsheet oriented database, and a macro facility for storing and recalling commonly used keystrokes. It supports the AppleTalk network and provides two-way file compatibility with Multiplan and Chart for the Macintosh, Lotus 1-2-3 for the IBM PC. and applications that support Microsoft's SYLK format.

The Excel spreadsheet provides you with a 256 column by 16.384-row work area. You can view and reference multiple spreadsheets, consolidate worksheets, enter multiple variable problems or situations, and vary the borders, number formats, and font styles and size. You can assign names to cell references, numbers, and mathematical expressions and call four windows into a worksheet. You can produce instant "what if' graphics with Excels charting abilities, which are functionally identical to Microsoft's Chart for the Mac. Excel files can be read directly into Chart, and Excel can read Chart files When you alter numbers in a spreadsheet window, charts in separate windows are instantly updated. For data comparisons, you can open more than one chart window for the same or different data. The charting facility also has 42 predesigned charts, the ability to relocate objects on screen, and your choice of font, range, scale, and patterns.

The database is an ancillary function of Excels spreadsheet. With it, you can sort, extract, and display information in a variety of ways. The database lacks form- and report-design capabilities: however. Excels formatting capabilities let you create reports. It does let you remove data for analysis in a different section of your work area.

Excels suggested retail price is $395. It requires 512K bytes of memory and will work with the Macintosh XL.

¿Se fiaba mucho Microsoft del éxito de Excel? Pues no sé, pero unas páginas más adelante la empresa anunciaba su solución de hoja de cálculo para el Mac:

Anuncio de Microsoft de su hoja de cálculo para el Mac, Multiplan, más Microsoft Chart para hacer gráficas. Se hace eco de que Multiplan utiliza todas las características amigables del Mac. También anuncian que están disponibles para el Mac Word, File y BASIC. — ¿Créiais que lo del caos de productos de las grandes tecnológicas era cosa de ahora? Pues hace cuarenta años Microsoft hacía publicidad de su hoja de cáculo Multiplan para Mac mientras anunciaba el lanzamiento de Excel para la misma plataforma…

Y en la lista de productos tenemos nada más y nada menos que el PC AT de IBM, con su 80286 y sus 256 KBs de RAM en el modelo básico (apenas cuatro mil dólares de la época):

IBM PC AT

The PC gets down to business

The IBM PC AT comes in two basic configurations. The basic model ($3995) comes with 256K bytes of RAM (random-access read/write memory), one of IBM's new high-capacity 1.2-megabyte disk drives, and a combination floppy disk/hard-disk controller card. Available for an additional $1800, the enhanced model adds 256K bytes of memory, a 20-megabyte hard-disk drive, and a serial/parallel interface adapter (see photo 1). Both systems are based on Intel's 80286 processor and have eight I/O (input/output) expansion slots and a battery-backed clock/calendar.

The AT comes with IBM's usual voluminous documentation. It includes a setup guide, an operations guide, and a BASIC manual, all in IBM's standard boxed looseleaf format. An unwelcome addition is a variety of small pamphlets packed in each box. While these are intended to be helpful quick guides, they are easy to misplace and might confuse as much as inform.

By the way, the BASIC manual is now complete. You don't have to send in a coupon and replace pages to get up-to-date documentation.

Power Supply and Keyboard

The power supply is 190 watts, as opposed to the 63 watts in the PC and 130 watts in the XT. This much power is needed. The PC is underpowered, causing many users to have hard-to-trace problems when adding to their systems. The XT's supply is much better but would be inadequate for the AT's two hard-disk drives. Since what goes in as electricity always comes out as heat, IBM has incorporated an innovative variablespeed fan that runs faster (and louder) as the internal temperature rises. Since my system was lightly loaded, the noise level never became obtrusive. A notable addition to the AT is a line-voltage select switch that lets it run on European 220-volt power.

The AT's keyboard and interface are more sophisticated than those on the PC and they are not compatible. You cannot use an AT keyboard on a PC. A single-chip microcomputer on the system board manages the keyboard and related functions. Any PC software that goes directly to the keyboard interface hardware, some key-translation programs, and many games will not work on the AT.

The keyboard layout is similar to that used on an IBM Selectric typewriter (see photo 2). The Shift, Control, Enter, and backspace keys have all been enlarged. Some of the less frequently used keys, such as backslash, grave accent. Print Screen, and Escape, have been moved to peripheral portions of the keyboard.

Three status lights have been added to the Caps Lock, Scroll Lock, and Num Lock keys— this is a welcome feature. The only new key, Sys Req, causes the keyboard handling software that's in ROM (read-only memory) to generate a software interrupt whenever the key is pressed or released. This lets the user signal the operating system for attention. PC-DOS currently ignores Sys Req.

To go with its international power supply. IBM provides six different versions of the AT's keyboard for foreign languages. The layout and internal scan codes are all identical, but some of the key legends are different to permit use of symbols peculiar to specific languages. The standard display adapters can display these characters, and DOS 3.0 has a set of utilities to adapt itself to the specific keyboard type.

On the output side, the AT uses the standard PC display cards and so is completely compatible. Graphics generation is much faster than it is on the PC.

Much has been said about the inclusion of a key switch that disables the keyboard and locks the cover in place. It seems to me that this feature is of limited usefulness. You would have to secure the entire system and external wiring to prevent someone with malicious intent from interfering with a running program. A program can test the state...

Por cierto… ¿lo de la compatibilidad de los PCs? El AT venía con un teclado nuevo, y el software para los PCs anteriores de IBM que accedía directamente a sus teclados (juegos, por ejemplo)… no funcionaba en el AT. El paso del 8086 al 286, para sorpresa de nadie, también daba sus propios problemas.

El AT, por cierto, era el primero en poder usar los novísimos discos de alta densidad, con sus casi infinitos 1,2 megabytes (hablamos de discos de 5¼ pulgadas, claro), a 500 kilobits por segundo. Sorpresa: las unidades de disco también suponían un problema de compatibilidad: si escribías a un disco de doble densidad, este no necesariamente sería legible en otros PCs. ¿Sistemas operativos? PC DOS 3.0 (no, no MS DOS) o el Concurrent DOS de Digital Research.

Y de los anuncios, me quedo con el SORD IS-11C. ¿No os provoca una cierta ansiedad la bisagra de la pantalla?

Anuncio del IS-11C de Sord Compuetr. Se trata de un sistema de procesador de textos y correo elctrónico portátil programable en BASIC. La bisgra que soporta la pantalla es de menos de la mitad del ancho de dicha pantalla.

Dice la Wikipedia que llevaba un Z80 y que la resolución de la pantalla era de 256 × 64. No habla del peso ni de la batería (algo me dice que solo funcionaba enchufado a la corriente).

Y con esto me paso a la sección de programación, donde encontramos, primero…

0.8660254 ≈ √3/2

An algorithm that converts decimals to fractions

Si hoy en día incluimos en una revista un programa para convertir números decimales a fracciones con la capacidad de reconocer al menos unas cuantas raíces cuadradas (el programa reconocía las raíces de 2 , 3 y 5, y π y π²), explotan cráneos (el autor, por más inri, era un estudiante de medicina de Estocolmo). Y por si esto no fuese suficiente…

Computing Pi

Using infinite series to compute mathematical functions

(El programa usa la serie de Taylor de la arcotangente y da quince cifras de π, más que suficientes para básicamente cualquier cálculo práctico.)

En fin. Volvemos, con un poco de suerte, el mes que viene. Si queréis anticipar el «futuro», podéis hacer trampa aquí.

Compárteme:

Compárteme:

Compárteme:

Compárteme:

Compárteme: