Modula Worked

22
Jan/100

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One of the reasons Google has been so successful is that one of its core philosophies is efficiency. This standard of efficiency holds true in three areas: serving search results, processing products, and producing results. Google is also coming out with "Google Wave," which will help to make communication more efficient.

Google is looking to redefine the foundation that the internet is run on. An open-source development program called Go was just released today. Google believes that this program will combine speed and performance and will reshape software and development in favor of Google.

The program Go is based on one of the most popular language trees in the world, the C programming family. The difference between Go and other language programs is that Go combines the Python family with the Pascal/Modula/Oberon family in order to create faster and more dynamic programs.

Google explains the motivation behind this program in its FAQ. Some of these reasons include:

There has been no major systems language created in years even though computer landscaping has changed drastically.
Although computers have become much quicker, software has not.
Management of dependency plays a huge part in the development of software. But the "header files" of languages available in the C family are counterproductive to clean dependency analysis, and stack up quickly.
Many people are becoming bored with the traditional languages and are, instead, turning to more dynamically typed languages.
Some basic concepts, such as garbage collection, are not well supported by common system language.
The appearance of multi core computers has caused confusion with existing programs.

Google has come up with the new language Go because it believes that the internet and computers have developed a great deal over the last ten years, but the language behind them has not. But truth be told Google will reap a lot of benefits from not only having its own language but having this language used in thousands of software all around the world.

Jason is a freelancer specializing in technology and online media. Read more at JasonStockman.com.

Xerox Alto

History

The Alto was first conceptualized in 1972 in a memo written by Butler Lampson, inspired by the On-Line System (NLS) developed by Douglas Engelbart at SRI, and was designed primarily by Chuck Thacker. Manufacturing was sub-contracted to Clement Designlabs, whose team included Carl J. Clement, Ken Campbell and Fred Stengel . An initial run of 80 units was produced by Clement Designlabs, working with Tony Ciuffini and Rick Nevinger at Xerox El Segundo, who were responsible for installing the Alto electronics. Due to the success of the pilot run, the team went on to produce approximately 2000 units over the next ten years .

Several Xerox Alto chassis are now on display at the Computer History Museum in Mountain View, California.

Architecture

The Alto had a bit-slice processor based on the Texas Instruments' 74181 chip, a ROM control store with a writable control store extension and had 128 (expandable to 512) kB of main memory and a hard disk that used a removable 2.5 MB single-platter cartridge (Diablo Systems, a company Xerox later bought) similar to those used by the IBM 2310, all housed in a cabinet about the size of a small refrigerator. The Alto's CPU was a very innovative microcoded processor which used microcode for most of the I/O functions rather than hardware. The microcode machine had 16 tasks, one of which executed the normal instruction set (which was rather like a Data General Nova), with the others used for the display, memory refresh, disk, network, and other I/O functions. As an example, the bitmap display controller was little more than a 16-bit shift register; microcode was used to fetch display refresh data from main memory and put it in the shift register.

Apart from an Ethernet connection, the Alto's only common output device was a bi-level (black and white) CRT display with a tilt-and-swivel base, mounted in "portrait" orientation rather than the more common "landscape" orientation. Its input devices were a custom detachable keyboard, a three-button mouse, and an optional 5-key chord keyset. The last two items had been introduced by SRI's On-Line System; while the mouse was an instant success among Alto users, the chord keyset never became popular.

In the early mice, the buttons were three narrow bars, arranged top to bottom rather than side to side; they were named after their colors in the documentation. The motion was sensed by two wheels perpendicular to each other. These were soon replaced with ball-type mice, which were invented by Bill English. These were photo-mechanical mice first using white light and then using IR to count the rotations of wheels inside the mouse.

The keyboard was interesting in that each key was represented as a separate bit in a set of registers. This characteristic was used to alter where the Alto would boot from. The keyboard registers were used as the address on the disk to boot from, and by holding specific keys down while pressing the boot button, different microcode and operating systems could be loaded. This gave rise to the expression "nose boot" where the keys needed to boot for a test OS release required more fingers than you could come up with. Nose boots were made obsolete by the "move2keys" program that shifted files on the disk so that a specified key sequence could be used.

Several other I/O devices were developed for the Alto, including a TV camera, the Hy-Type daisywheel printer and a parallel port, although these were quite rare. The Alto could also control external disk drives to act as a file server. This was a common application for the machine.

Software

Early software for the Alto was written in the BCPL programming language, and later in the Mesa programming language, which was not widely used outside PARC but influenced several later languages, such as Modula. The Alto keyboard lacked the underscore key, which had been appropriated for the left-arrow character used in Mesa for the assignment operator. This feature of the Alto keyboard may have been the source for the CamelCase style for compound identifiers. Another feature of the Alto was that it was microcode-programmable by the user.

The Alto helped popularize the use of raster graphics model for all output, including text and graphics. It also introduced the concept of the bit block transfer operation, or BitBLT, as the fundamental programming interface to the display. In spite of its small memory size, quite a number of innovative programs were written for the Alto, including:

the first WYSIWYG document preparation systems, Bravo and Gypsy;

the Laurel e-mail tool, and its successor Hardy;

the Sil vector graphics editor, used mainly for logic circuits, printed circuit board, and other technical diagrams;

the Markup bitmap editor (an early paint program);

the first WYSIWYG integrated circuit editor based on the Conway and Mead paradigm;

the first versions of the Smalltalk environment

Interlisp

one of the first network-based multi-person computer games (Alto Trek by Gene Ball).

There was no spreadsheet or database software.

Diffusion and evolution

Technically, the Alto was a small minicomputer, but it could be considered a personal computer in the sense that it was used by a single person sitting at a desk, in contrast with the mainframes and other minicomputers of the era. It was arguably "the first personal computer", although this title is disputed by others.

The Alto was never a commercial product, although several thousand were built. Universities, including MIT, Stanford, CMU, and the University of Rochester received donations of Altos including IFS file servers and Dover laser printers. These machines were the inspiration for the ETH Zrich Lilith and Three Rivers Company PERQ workstations, and the Stanford University Network (SUN) workstation, which was eventually marketed by a spin-off company, Sun Microsystems. The Apollo/Domain workstation was heavily influenced by the Alto.

The White House information systems department acquired an Alto, and sought to lead Federal computer suppliers in its direction. The EOP issued a request for proposal for a computer system to replace the aging OMB budget system, using Alto-like workstations, connected to an IBM-compatible mainframe. The request was eventually withdrawn because none of the mainframe companies could supply such a configuration.

In 1979, Apple Computer's co-founder Steve Jobs visited Xerox PARC, where he was shown the Smalltalk-80 programming environment, networking, and most importantly the WYSIWYG, mouse-driven graphical user interface provided by the Alto. He reportedly was not impressed by the first two, but was excited by the last one, and promptly integrated it first into the Apple Lisa and then in the Macintosh, inviting several key researchers to work in his company .

In 19801981, Xerox Altos were used by engineers at PARC and at the Xerox System Development Department to design the Xerox Star workstations.

Xerox and the Alto

Xerox itself was slow to realize the value of the technology that had been developed at PARC. After their unhappy experience with SDS (later XDS) in the late 1960s, the company was reluctant to get into the computer business again with commercially untested designs.

Before the advent of personal computers, like the Apple II models with Visicalc, drove a disbelieving IBM to put their name on the derivative IBM PC, the computer market was dominated by costly mainframes and minicomputers equipped with dumb terminals that time-shared processing time of the central computer. So, through the 1970s, Xerox showed no interest in the work done at PARC. When Xerox finally entered the PC market, with the Xerox 820, they pointedly rejected the Alto design and opted instead for a very conventional model, a CP/M-based machineith the then-standard 80 by 24 character-only monitor, and no mouse.

With the help of PARC researchers, Xerox eventually developed the Xerox Star (and later the cost reduced Star; the 6085) office system, which included the Dandelion and Daybreak workstations. These machines, based on the 'Wildflower' architecture described in a paper by Butler Lampson, incorporated most of the Alto innovations, including the graphical user interface with icons, windows, folders, Ethernet-based local networking, and network-based laser printer services.

Xerox only realized their mistake in the early 1980s, after Apple's Macintosh revolutionized the PC market thanks to its bitmap display and the mouse-centered interfaceoth copied from the Alto. While the Xerox Star series was a relative commercial success, it came too late. The expensive Xerox workstations could not compete against the cheaper GUI-based workstations that appeared in the wake of the first Macintosh, and Xerox eventually quit the workstation market for good.

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