RAK’s OS Adventures Double Bill – Atari TOS & SymbOS

Author’s Note – Since I didn’t write an article two weeks ago, I’ve decided to try to make up for that somewhat by writing a set of short articles on a couple of operating systems that I’ve recently acquainted myself with. Hope you enjoy!

Historical Operating Systems – Atari TOS

As I’ve indicated before ([1], [2], [3]), the mid-1980s transition from 8-bit to 16-bit processors in personal computers marked a turning point, from computers which would boot up into a BASIC interpreter to ones which would incorporate full graphical user interfaces, and towards development of multimedia programs such as WYSIWYG word processors, desktop publishing and graphics manipulation suites. A lot of the competitors in the preceding 8-bit computer wars had been lost to market pressures, leaving only a few primarily American and British competitors to fight it out in the late 1980s.

Atari was one of these competitors. Atari was one of the few console-producing companies to survive the Great Video Game Crash of 1983, despite two games, the poor-quality port of Pac-Man with its flickering sprites and the turgid, over-produced E. T. the Extra-Terrestrial, on the Atari 2600 console being partially responsible for the crash. Nevertheless, the crash of the video game console market led Atari’s parent company, Warner Bros., to sell off Atari.

Atari’s computer division was responsible for the Atari 400/800 computers which had been strong competitors against the Apple II and Tandy Radio Shack TRS-80 computers, and had maintained sales against the Commodore 64. With strong sales in Europe, where the Commodore 64 had a harder time competing against the low-price British computers such as the Sinclair ZX Spectrum, this part of Atari’s operations was still desirable.

One man to whom Atari looked particularly desirable was Jack Tramiel. Tramiel had founded Commodore International in the 1950s, first repairing and selling typewriters, then moving onto calculators, but soon branching into the nascent computer market. Commodore’s PET and VIC-20 models had been highly successful, but it was the Commodore 64 which would forever cement the company’s name in computer history. However, Tramiel’s market tactics involved quickly dropping the price of the Commodore 64, effectively underpricing every other computer in the North American market. Tramiel’s tactics would end up making the Commodore 64 the single-most successful home computer model ever produced and wiping out many of the competitors.

It has been suggested that one of Tramiel’s main targets was Texas Instruments, who had almost ruined Commodore during the 1970s, and the continuous price-dropping of the Commodore 64 did end up wiping Texas Instruments from the home computer market in the process. Nevertheless, this aggressive price strategy did come at the cost of profits, and in 1983, Jack Tramiel was unceremoniously booted from the Commodore company.

All of this made Atari a rather tempting acquisition for Tramiel, who bought Atari in 1984. Atari originally had their eyes on the Amiga, but after losing a protracted battle with Commodore for the Amiga chipset after Tramiel’s takeover of the company, Atari had to develop a replacement. The computer they developed was the Atari ST, or Sixteen/Thirty-Two (a reference to the Motorola 68000’s 16-bit external bus and 32-bit internal architecture). Arriving on the market two months before the Amiga, the Atari ST would be competitive in the late-1980s, particularly in Europe, where the home computer market moved more slowly towards the adoption of IBM PC-compatibles, but as with the Amiga and most other competitors, lose ground into the 1990s.

The operating system of the Atari ST was a licensed version of the Digital Research GEM environment, known as Atari TOS. Originally shipped on floppy disc, it was later incorporated onto a ROM chip, similar to the contemporary RISC OS for the Acorn Archimedes. Unfortunately, though, Atari TOS feels like the most sparse of the operating systems of the late-1980s 16/32-bit microcomputers, even considering that it is on a ROM chip rather than the floppy discs used for most other contemporary operating systems. While RISC OS had a powerful BBC BASIC interpreter that could be used to build graphical applications, and AmigaOS and Mac OS at least came with calculators or clocks, Atari TOS really only came with the basic OS utilities and not much more.


At least graphically, Atari TOS matched up to early versions of AmigaOS and RISC OS – although these graphics would remain into the 1990s.

What’s more, Atari TOS was a single-tasking operating system right until the shipping of the MiNT-based MultiTOS package in the 1990s; this at a time when AmigaOS had possessed pre-emptive multitasking since 1985, when Mac OS had got cooperative multitasking in 1987, when RISC OS had cooperative multitasking since its release and when Microsoft Windows was giving even the x86-based MS-DOS computers multitasking capabilities. Given that I have complained about the slow adoption of multitasking by Mac OS and the cooperative multitasking model of RISC OS, I think it stands to reason that I do not regard Atari TOS as an especially sophisticated operating system, even by the standards of the 1980s.

It’s a shame, in a way, since the Atari ST itself seems to have been a sophisticated, yet inexpensive computer that could compete well against the Macintosh and Amiga in terms of pure grunt. Plenty of games seem to have been cross-developed between the Amiga and Atari ST, the common element of a Motorola 68000 microprocessor helping matters. The Atari ST was also the first platform for which the Allegro game library was developed (hence the name of the library, originally derived from Atari Low-Level Game Routines). The operating system, on the other hand, did not match up to the sophistication of the computer it ran on, and while Mac OS and the early versions of Microsoft Windows led to greater development down the line, AmigaOS was a sophisticated operating system ahead of its time and RISC OS is still being developed today for a processor architecture which is very much alive, Atari TOS doesn’t really seem to have any particular historical significance beyond the fact that it was there.

RAK’s OS Adventures – SymbOS

From there, I move onto an operating system which is very much more sophisticated than its hardware requirements would indicate. The 8-bit computer wars of the early 1980s typically revolved around two types of processors. The MOS Technology 6502 was used in the Commodore 64, the Apple II and the BBC Micro, among others, and could indirectly trace its lineage to the Motorola 6800. The Zilog Z80, on the other hand, was used in the Tandy Radio Shack TRS-80, Sinclair ZX Spectrum, the Amstrad CPC and PCW ranges and the MSX computers and uses an extended version of the instruction set architecture of the Intel 8080.

In certain regards, the MOS 6502 is a superior processor; while Z80 processors typically ran at a clock rate of approximately 4MHz in most early-1980s microcomputers, MOS 6502 processors could be competitive at a clock rate four times slower than that. In other regards, the Z80 has the advantage; with more registers and a more sophisticated instruction set, it is a more friendly processor to program for. Both processors are still being sold today, mostly for embedded systems; Zilog still exists and has a strong market selling Z80 and Z80-compatible processors for embedded systems, some quite a bit more powerful than the 1980s models (RS Components currently has a Zilog Z180 running at 20MHz for €11.40 for an individual processor), while Western Design Center, established by a co-holder of the 6502 patent, still sells 6502-compatible processors.

No matter how popular these processors may have been in their day, they seem rather old-hat even by the standards of the Intel 80286, the Motorola 68000 or the ARM2, let alone today’s multi-gigahertz Intel processors. Nevertheless, sometimes sophisticated programming can trump raw power, as seen with SymbOS, an operating system for Z80-based computers.

SymbOS is the project of a German programmer, known by the pseudonym Prodatron, and is developed for the Z80-based Amstrad CPC, MSX and Amstrad PCW computers. The Amstrad computers were particularly popular in Germany, where they sold in numbers comparable to the Commodore 64 in that market, while the MSX computers were developed as a standard for Japanese microcomputers. These computers typically came with 64 or 128kB of RAM and Z80 processors clocked at 4MHz – only moderately powerful for 1984 or 1985, when these computers were released.

All of that makes SymbOS look especially impressive when considering what you get out of it. SymbOS provides full pre-emptive multitasking, of the same level of sophistication as AmigaOS, developed for a computer with twice as much RAM as standard and a processor a generation older. It provides a full GUI system, similar in appearance to that of Microsoft Windows 95, and similar in sophistication to Atari TOS or Mac System 6 – and more sophisticated than Microsoft Windows 1.0. It can run sound and video applications. It can support 128GB FAT32 hard drives – when Microsoft Windows couldn’t do this until Windows 98.


It even looks pretty nifty as well.

Yes, the OS was first released in 2006, twenty years after the release of the computers it runs on. Yes, it’s not the only graphical user interface for an 8-bit computer – GEM was originally developed for the Commodore 64. But it’s got pre-emptive multitasking, sound and video capabilities and support for large hard drives, all on an 8-bit processor originally developed in the 1970s, and on as little as 128kB of RAM (although more is suggested for best performance). It makes me wonder – if this sort of operating system can be developed for an 8-bit computer, would it be possible to improve some of the 32/64-bit operating systems of today if there were generally more proficient programmers developing them?