HJS22 ARCHITECTURE

The HJS22 has the following hardware registers:

  • 8 bit Accumulator (Acc).  [TTL 7475] 
  • 16 bit memory address registers (M-reg).  [TTL  74191]
  • 24 bit Program Status Word (PSW):
    8 bits Status (Carry, Shift, Condition, Interrupt level)   [TTL 7475] 
    16 bits Program Counter.  [TTL  74191]
  • 24 bit Instruction Register:
    8 bits Instruction opcode.  [TTL 7475] 
    16 bits Operands Address register (I-reg).   [TTL 7475] 
  • ALU result register (R-reg).   [TTL 7475] 
  • Micro-code address register (P-reg).  [TTL 74175]

This pdf file (1 Mbyte) contains scanned pages of the architecture.
Pages 1 & 2      Final architecture, dated 22 July 1979.
Page 3               One of the early versions, dated 5 September 1976.

An overview of the HJS22 instructionset can be seen on these HJS22 refenence card.
(typed at the back of two 80 column punch cards)

        Reference card                            Reference card

HJS22 Micro code