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Introduced in 1987, the Amiga 500 was the most succesful and widely sold computer in Commodore's Amiga line of PCs. It was especially popular as a home computer, because it was capable of serious tasks such as word processing, but also had advanced graphics and sound capabilities that made it suitable as a gaming platform. A huge library of games and accessories made the Amiga series a great success for Commodore.
Although officially known as "Commodore Business Machines", Commodore unfortunately never managed to shake off their "consumer" image and were unable to compete with that hulking giant of Serious Computing, IBM. When PCs and Macs got high-performance graphics and sound in the early 1990's, Commodore rapidly began losing terrain and had to file for bankruptcy in 1994.
Nevertheless, the huge installed base of Amigas, especially in sound and video production circles, meant that the Amiga scene remained very much alive, and even today there are still companies producing Amiga-compatible hardware and software.
Anyway, this is the A500. Like most home computers of the day, all major parts are contained inside a flat plastic case with a keyboard on top. The heart of the A500 is an MC68000 processor, designed by Motorola. Running at 7 MHz, the Amiga has 512 KB of RAM, a floppy drive, and a couple of ports to connect a display, mouse, joystick and other peripherals.
I've opened up all the major chips inside. These are:
- MC68000 CPU
- 8372A "Fat Agnus" motherboard controller
- 8362R8 "Denise" video processor
- 8364R7 "Paula" audio processor
- 5719 "Gary" I/O controller
While the MC68000 was manufactured by Signetics (though designed by Motorola), all the other chips were custom made for the Amiga by MOS Technology, Commodore's own IC manufacturing company. All chips are made in NMOS technology.
This chip drives it all: the 68000 processor. Although designed by Motorola, this particular chip was made by Signetics. It's housed in a humongous 64-pin DIP package, by far the largest DIP you'll ever find! The MC68000 was a very successful microprocessor used in dozens of computers. Famous examples include the first Apple Macintosh, the Atari ST, Sega's Mega Drive, many scientific computers from HP, Sun, SGI and DEC, and lots of printers, copiers, measurement equipment and the like.
A composite image showing the entire chip. It was named 68000 because that's how many transistors are inside, and also because it follows nicely after Motorola's previous CPU design, the 6800.
Signetics have signed their work in this little corner. There's also a funny little structure on the left: although it says "circuit", it only contains a couple of vertical bars made in each layer of the chip. No circuits there.
A little further to the left we find this funny structure. This is a test circuit containing a few transistors (big as well as small) connected to a couple of test pads.
The engineers apparently had a few square microns left to fit in another Signetics logo in the top right corner.
In another corner we find these mask identification markers.