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