|MCP-1600 - A processor made by Western Digital, consisting of at least
four separate integrated circuits, including the control
circuitry unit, the ALU, two or four ROM chips with
microcode, and timing circuitry.|
The ALU chip contained twenty-six 8-bit registers and an 8-bit ALU, while the control unit supervised the moving of data, memory access, and other control functions. The ROM allowed the chip to function as either an 8- or 16-bit chip, with clever use of the 8-bit ALU. Further, microcode allowed the addition of floating-point routines (40 + 8 bit format), simplifying programming (and possibly producing a floating-point coprocessor).
Two standard microcode ROMs were available. This flexibility was one reason it was also used to implement the DEC LSI-11 processor as well as the WD Pascal Microengine.