OPCODEs for Control Unit

The following table outlines the different functions enabled given specific opcodes

Outputs

OPCODE
OE
ASEL
SHSEL
CLR
STORE
C{7:0}
CO
OUT
0000
1
0
0
0
0
0
0
00
0001
1
0
0
0
0
0
0
00
0010
1
0
0
1
1
INCR
1
01
0011
1
0
0
0
0
0
0
00
0101
1
1
0
0
0
0
0
11
0110
1
0
0
0
0
0
0
00
0111
1
0
0
0
0
0
0
01
10??
1
1
0
0
0
0
0
10
11??
1
0
0
0
0
0
0
10

Opcode Descriptions

OPCODE
INSTRUCTION
DESCRIPTION
0000
BOOLEAN
0001
BOOLEAN
0010
MULTIPLY
Initiates multiply operation; FSM sequences through 8 states, completing ADD and SHIFT RIGHT operations
0011
BOOLEAN
0101
SUBTRACT
Asserts ASEL, which is taken as the CIN of the adder and XORed with the "B" bits for inversion
0110
BOOLEAN
0111
MULT_HIGH
Used to provide upper 8 bits in multiply operation
10??
SHIFT
11??
SHIFT

Last Update: December 12, 1996