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The 5'th September 1992 and I begin by starting to think about the
instruction set. I decide to have 16 registers. This way the
register number will fit in 4 bits. The computer will be a 40-bit
machine. Hopefully I will be able to fit 2 instructions in
each 40-bit "word", each one taking only 20 bits. This way I can
execute 2 instructions per instruction fetch. On this page the right
column indicates the number of bits the instruction operands
require.
The instruction groups are:
o NOP (No operation)
o Arithmetic (Multiply, Add, Subtract), integer and floating point
o Logical
o Shifts and rotates
o Loads
o Individual bit testing, setting and resetting
o Jumps, Calls, Branch (relative jump) and returns
o I/O instructions and control
