When we speak of operating systems, the word 'alternative' is not quite as it is from the dictionary. Mac OS X is an alternative to Windows just as much as Windows is an alternative to OS X. It is simply one choice over the other. But with OSes, 'alternative' has come to mean 'niche', 'minority' and 'hobby'. How can GEOS be 'alternative', if it was at one time more popular than Windows?
OSes can change over time, even change purpose. OS/2 and BeOS are considered alternative, despite being big important OSes in their day. I believe that the same is of GEOS. At the end of this article, I will cover how GEOS has been retro-fitted by fans to add modern day functionality, as well as the OS that came after GEOS, extending the life of GEOS well into new millennium. The fact that people still boot GEOS on real Commodore 64 hardware and make real things with them, because they can, certainly defines GEOS a hobby OS. Because those who run it on real hardware are few and far between, that makes GEOS a minority OS; and because GEOS is generally only run by core C64 fans it also makes GEOS a niche OS. :)
3.4 Hardware Requirements
Although GEOS later became available on the Apple II and then eventually the PC (more about this later), this article will be covering the Commodore 64 version of GEOS due to free availability and wealth of accessible information. I also own a real GEOS disk set for my Commodore 64 and hope to make use of them in this article.
GEOS ran on any Commodore 64 home computer. Because of the popularity of the Commodore 64 as a games machine, GEOS can also be easily run on most C64 emulators on modern computers. GEOS itself is now available for free download - more details soon.
The Commodore 64
Commodore Business Machines released the C64 in 1982 at a price of $595. Designed primarily as a home computer for playing (initially educational) games and business software, its low price and powerful features made it a runaway success. Here follows some technical details of the hardware.
1 MHz 8-bit MOS Technology 6510 Processor
The 6510 was a 6502-based processor, that which can be found (as variants) in the Atari 2600, NES, Apple II & BBC Micro computers. It is a RISC style processor, utilising very few registers (Just A, X, Y & a 256-byte Stack)
- 64 Kilobytes RAM (+20K ROM of which 7 KB Kernal)
- 16 Colours in 40x25 text mode (320 x 200 resolution)
- 8 Sprites
MOS 6581 (C64rA,B) / 8580 (C64rC) SID sound chip
Three sound channels (2 MIDI like sound synthesisers, and one White Noise)
'Datassette' Tape Drive, later, 1541 Disk Drive
Programs on tape cassette. Later a 5¼" Disk Drive was released with support for 170 KB per disk.
As you can see, this is a very tight amount of space to fit a full operating system, including userland apps! The original Mac OS was 400 KB, with 128 KB of RAM to play with.