Commodore's Amiga 500 was the low-end version of the Amiga 2000 and the main competitor of Atari's 520/1040 ST range. The A500 was superior in almost every area, apart from its MIDI capabilities and the disk drive, which was not only slow but very noisy as well and a bitter feud quickly developed between owners of these rival machines.
Hardware wise, the A500 is very similar to the Amiga 1000, the main internal differences being an increase in memory fom 256 KB to 512 KB and the addition of another custom chip named "Gary" (the only Amiga chip with a male name). This is a new I/O chip that controls the disk drive and also performs address decoding. This chip is also used in the high-end A2000.
The A500 was easier to upgrade than both the ST and big box Amigas, thanks to an expansion port located in the bottom of the case. Owners could simply insert a small board which contained an extra 512 KB of Ram and a battery-backed clock. The popularity of this upgrade meant that more 1 MB software (both 1 MB versions of 512 KB software and 1 MB only software) was released for the Amiga than the ST, which had to be taken apart to expand the memory.
Over the course of the A500s lifespan several different packages were available, the most basic of which included only the computer, TV modulator and Workbench disks. A number of bundles were also sold, such as the best selling "Batman Pack" which was released in 1989 and included 3 games and Deluxe Paint 2.
The A500 was discontinued in 1991 and replaced by the short lived Amiga 500 Plus.
The Amiga 500 is a "cleaned" A1000, "cleaned" means plenty of TTL glue logic was replaced by custom IC which was named Gary. A500+ it is a new generation of custom IC's so called ECS (A500 have OCS). A500+, A3000, A600 have new graphics modes (1280 dots in line without overscan and 31Khz scanning similar to VGA - limited to 640 pixels in line with 4 colors).
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Built-in keyboard, 95 keys
7.09379 MHz (PAL) 7.15909 MHz (NTSC)
OCS based chipset: 8370/8372 Fat Agnus (memory controller and blitter), 8362R5/8362R6/8362R8 Denise (video control chip), 8364 Paula (sound & I/O), 5719R2 Gary (I/O)