Retro Computer Story: The Commodore 64

The Commodore 64 was a very popular home computer in the 1980s. The name adopted by the manufacturer, the Commodore Business Machine, was initially Vic-30, but before its distribution it was changed to Commodore 64.

Jack Tramiel, il fondatore della Commodore Business Machine su

The American Commodore was founded in 1964 by Jack Tramiel to repair typewriters. Tramiel is far-sighted and looks at the computer world with a perspective that will become the brand of the company: “Computer for the masses, not for the classes”. In short, an affordable technology that converts millions of users to what some have called “diabolical machines”.

The design of the Commodore 64 came to life in January 1981 when Commodore MOS Technology engineers decided to create a new high-performance graphics and sound chip for the arcade market. In November of the same year, with the chip completed, President Commodore Jack Tramiel will convert the project to a home use by implementing the new technology in a 64k computer. The VIC-30 (later Commodore 64) was born.

Pubblicità del Commodore 64 su
La Storia del Commodore 64 su

The Commodore 64 is the best-selling computer model in the world, a record that is also found in the Guinness Book of Records: in 1986 over 10 million copies were sold worldwide. It was marketed until 1993, when the units sold were just 700 thousand.

La Storia del Commodore 64 su

The Commodore 64 was initially built using the same Vic-20 case to keep production costs low. After a few years, the Commodore slightly changed the aesthetics of the computer along with other minor changes, renaming it 64C.

Il Commodore 64c su

The simplicity of use and ease of programming of this new computer was superior both to its predecessors (PET and Vic-20) and to the other competing home computers. Thanks to this and its selling price, in a short time it became the best-selling computer in the history of computer science.

Lo Schermo del Commodore 64 Basic. La Storia del Commodore 64 su

The Commodore machine could count on a series of peripherals (disk drives, recorders, printers and joysticks) that increased its value and utility, even in professional fields. The peripherals were also compatible with the previous Commodore computer model, the VIC-20, of which the C64 was the natural upgrade. For many programmers, the Commodore 64 was one of the first computers they came into contact with, even though the machine’s success was guaranteed more than anything else by recreational use. The library of games for the commodore 64 was in fact immense and presented real milestones in the history of video games.

The success of the Commodore 64 was immediate and, thanks to the widespread distribution, it succeeded in achieving sales results unthinkable for that time. Another record of this machine concerns the life of the product: the Commodore 64 remained on the market for ten long years, until the advent of the 16-bit computer generation, dominated by the Amiga and Atari ST.

The Commodore 64 used the 6510 microprocessor, with 64 KB of RAM and 20 KB of ROM with the KERNAL and the CBM BASIC version 2.0: audio and video were managed by two separate chips. The original hardware design of the Commodore 64 was the work of a group of about twelve engineers who subsequently left the Commodore.

Il chip MOS del Commodore 64 su

The Commodore 64 had a video chip (VIC-II) that could produce 16 colors (a greater number of colors was obtainable with particular software algorithms). It had a maximum resolution of 320 x 200 points in the “hi-res” mode (2 colors possible for each cell 8 x 8), and 160 x 200 in the “multicolor” mode (4 colors possible for each cell 8 x 8). The text mode provided a 40-column view for 25 lines. The font of default characters was editable (it was enough to order the graphic circuit to take the character definitions from RAM instead of from ROM). The chip managed up to 8 hardware sprites, that is graphic forms easily manageable from the chip to get images and animations, drawn above the traditional screen. The VIC-II was able to generate an interrupt in any scan line of the desired video. This allowed the central processor to reprogram it “on the fly” in order to use a different set of parameters for different areas of the screen, for example to reuse the 8 sprites again, having 16 or even more available on the screen (over 50 in some cases).

Audio support exceeded all computers of the same class. At the base was the SID-6581 chip, designed by Bob Jannes (the designer of the VIC-20), which could reproduce three hardware voices, allowing the reproduction of the human voice without additional hardware. This chip, for its time, was a legendary product.

At the synthesis level, the CIS constructed the sounds starting from three basic waveforms, plus the ADSR. Unfortunately, the sine wave was missing from these waveforms. The number of entries could be “increased” by software techniques. The SID could also sample analog signals, with 4-bit resolution. The Commodore 64, equipped with this technology was at the top of the range, an “audio” reference point in the industry for many years to come.

Il Datassette del Commodore 64 su

Initially only the magnetic cassette memory was available, that is the common audio cassettes on which data and programs were recorded encoding them on frequencies of some Khz. The cassette unit (Datassette) was rather slow, but what was lost in speed was gained in reliability. It was also possible to use alternative loaders / savers to those of the operating system, which allowed – under pain of less reliability – faster loading and saving on tape. A particular signal identified the beginning of a data block (generally, a program), and to be able to find it the user was generally forced to slowly scroll the cassette in Play mode. The rev counter at the side of the box was used as a sort of “index” to get to the desired program more quickly.

Il Disk Drive 1541 / 154I del Commodore 64 su

Later, the 154I floppy disk reader was available (the Commodore 64 disk drive was called 154I and not 1541: but this detail was never captured by the public, and virtually everyone called it 1541), which accepted 5.25 “disks and it transferred data at a much higher speed.The 154I had a 6502 processor that was identical to that of the main computer, and some programs used it as a coprocessor to have more computing power available.

The presence of the microprocessor in the 154I made it possible for this unit to operate in a completely independent way: for example, it was possible to format a floppy and, at the same time, continue to write its own program (or, even, perform a loading from the tape drive ). The combination of Commodore 64 + 154I thus constituted a multiprocessor system.

Although the C64 was not the perfect machine (for the time) the designers who worked on it are firmly convinced that the great technological steps that they have managed to make are to be attributed to the great freedom that the Commodore work environment gave them. The design team was autonomous. Each engineer did his own market research, developing his own specifications and following his “child” up to production. But as soon as the C64 product was completed, freed from all bugs, and Commodore realized it had a winner (and therefore a lot of money) the corporate bureaucracy arrived. The designers were set aside to make room for marketing partners, experts with the role of “helping” designers. “As soon as marketing in product definition comes into play, you can never be quick in development …” says one of the historic designers of Commodore. “… and burn the paper to have a unique product, because the marketing rule imposes a product compatible with something else …”. “… when you put so many people on one project, all you end up doing is justify yourself. I knew that the C64 was technically as good as it was cheap, but those marketing people can only say things like – won’t sell because it doesn’t have this or that feature … it doesn’t work! – … The freedom we had in creating the Commodore 64 project will never exist again in this environment “.