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A Small MC68008 Computer System
This report presents a design for a minimal computer system using the MC68008, exploiting the unique features of the MC68008 to create a small (23 chip) computer which nevertheless executes a full 32-bit instruction set and is completely software compatible with 16-bit 68000 systems.
The minimal computer system presently consists of the MC68008 processor running at 8 MHz, 32 kilobytes of static RAM, 32 kilobytes of EPROM, two channels of serial I/O, a parallel printer output port, and a programmable timer.
The serial I/O, timer, handshake lines for the parallel printer port, and several other control functions are all provided by a MC68681 DUART (Dual Universal Asynchronous Receiver/Transmitter). Memory is provided in the form of one 32K x 8 static RAM, and one 32K x 8 EPROM.
Two pushbuttons and two status lights are provided. The pushbuttons are used to reset the system, and to generate a non-maskable interrupt to the processor. One of the lights indicates when the processor is halted, while the other is user programmable.