Personal Computer Museum

Hobby Computers of the 80's

By Jim Butterfield

©2005 (shown here with permission)

Jim Butterfield

Prologue

One sometimes wonders what to expect from a presentation that is based on nostalgia. Back in those days, our computers were hand-cranked with a wind-up key. I finally got a foot-pedal unit, which left my hands free to operate the input abacus. One of my friends devised a wind-powered computer, but it blew away...

I. A little about myself

I'm Jim Butterfield. My first encounters with computers took place back in 1963. My background was math and electronics, working mostly in the field of telecommunications. My first machine was a computer nobody had heard of: the Collins C8401, programmed in assembly language.

So when microcomputers started to arrive in 1976, I had an advantage over most hobbyists: I'd worked with computers for a dozen years or more. I was in a good position to write about these devices, which were unfamiliar to most readers. And I did so.

Most of my experience was with Commodore computers. What follows will be from that viewpoint, and I'll talk almost exclusively about the 8-bit world. It was a fun time.

I should mention that I have never been an employee of Commodore, or owned stock in the company. My viewpoint is that of an outsider, although Commodore personnel have always been open and frank in responding to the many questions I have asked over the years.

II. Industry prologue

IBM 029 Punchcard MachineBy 1963, transistors had replaced vacuum tubes, and the industry had settled into a form of stability. Although there were a number of computer manufacturers, IBM enjoyed over two-thirds of the market. Industry watchers often referred to 'IBM and the seven dwarfs.'

Why did IBM dominate? In part, it was because they had been in the data processing business long before the arrival of computers. Using Hollerith punched cards, IBM had an array of "unit record" equipment such as keypunch devices, tabulators, and sorters; they had decades of experience in handling data.

A second reason for IBM's strength was that they leased their equipment rather than selling it. And with the lease came support, with system engineers on site or on call. Industry people talked about being sheltered by the "IBM umbrella."

And, as a general rule, software was free. Assemblers, compilers, report generators ... phone your IBM rep and he'd send over a copy. Need personnel training? IBM would do it free. Or, at least, at no extra charge.


III. Underground fun

Line Printer ArtEven in those days, computer programmers and operators would have secret amusements. Secret, because senior management would have misgivings about 'horsing around' on a multi-million dollar computer.

Pictures were drawn on the line printer, patterns generated on punched card or paper tape, games were created and played, jokes were being played on co-workers, and music was being played on these computers. Note how the word 'play' seems to be repeated.

The seemingly impossible job of playing music on computers that had no speakers was accomplished in several ways. The hammers of line printers could be carefully timed to produce sounds of a selected pitch; the paper-advance chain could be declutched and made to furnish drum rhythms. And a transistor radio placed adjacent to the CPU, where it would pick up the electromagnetic emissions, would play a selection of popular numbers.

IV. Transitions

In the time frame between 1963 and 1971, there were a number of changes that helped shape the nature of microcomputers-to-come.

DEC PDP-8achineMinicomputers started to gain acceptance in 1965 with the Digital Equipment Corporation PDP-8. These "minis" were stripped-down computers, designed to sell for a paltry $10,000 or so. In the early days, magnetic core memory was a major cost impediment, and attempts were made to circumvent it with other resources. I recall that the PDP-8S used a serial memory (a mercury column delay line). It was said that if you stamped on the floor, you could change its memory contents.

Minicomputer technology didn't have much effect on future microcomputers. But it's interesting to note that a powerful user group, DECUS, grew around the PDP series, and may have been a precursor to microcomputer user groups that appeared much later.

In 1965, General Electric introduced "Time-Sharing" service, where users could concurrently make use of a central computer. The terminal device was usually a Teletype machine. The major impact of time-sharing on the future microcomputers was its choice of language: Basic, both adored and vilified.

By 1971, the expensive and labour-intensive magnetic core memory that had been the heart of computers started to be replaced by semiconductor memory. This set the stage for ongoing price reductions, which we still see today.

This, in turn, spawned another product that was to become important in the future microcomputer world: the floppy disk. Magnetic core memory had been non-volatile: once loaded, it kept its contents even when power was off. Semiconductor memory needed to be reloaded, and the 8-inch floppy disk was created by IBM for this purpose. Initially, it was a read-only device, whose contents would be created at the IBM production facility.


  Return to the stories index Next Page >>