Instructions

The below table is copied from Appendix A of System Software: An Introduction to Systems Programming . Note that for format 3/4 instructions, the opcode is really 6 bits. The last two bits are used for bits n and i.

Notes

• P: Privileged instruction
• X: Instruction available only on SIC/XE
• F: Floating-point instruction
• C: Condition code (CC) set to indicate the result of the operation (<, =, or >)

List of Instructions

ADD m

Adds register A and the word at the address m, storing the result in register A.

ADDF m

Floating-point equivalent of ADD. The floating-point number stored at m (6 bytes or 2 words) is added to the value in register F and the result is stored in register F.

ADDR r1,r2

Adds the values of r1 and r2 together, storing the result in r2.

AND m

Performs bitwise AND on register A and the word at m. The result is stored in register A.

CLEAR r1

Sets register r1 to zero, effectively clearing it.

COMP m

Compares of register A to the word at m, setting the condition code.

COMPF m

Floating-point equivalent of COMP. The floating-point number stored at m (6 bytes or 2 words) is compared to the value in register F and the condition code is set.

COMPR r1,r2

Compares the values of r1 and r2, setting the condition code.

DIV m

Divides the value in A by the word at address m. The result is wrote back to register A.

DIVF m

Divides the value in F by the 2 words at address m. The result is wrote back to register F.

DIVR r1,r2

Divides the value of r2 by r1, storing the result in r2.

FIX

Reads the float in F, converts it to an integer, and stores it in A.

FLOAT

Reads the integer in A, converts it to a floating-point number, and stores it in F.

HIO

TODO

J m

Jumps to address m by updating the PC register.

JEQ m

Jumps to address m by updating the PC register only if the condition code is set to =.

JGT m

Jumps to address m by updating the PC register only if the condition code is set to >.

JLT m

Jumps to address m by updating the PC register only if the condition code is set to <.

JSUB m

Sets the L register to the current value of PC and then jumps to address m by setting PC.

LDA m

Loads the word at address m into the A register.

LDB m

Loads the word at address m into the B register.

LDCH m

Loads the byte at address m into the right-most byte of the A register.

LDF m

Loads two words at address m into the F register.

LDL m

Loads the word at address m into the L register.

LDS m

Loads the word at address m into the S register.

LDT m

Loads the word at address m into the T register.

LDX m

Loads the word at address m into the X register.

LPS m

TODO

MUL m

TODO

MULF m

TODO

MULR r1,r2

TODO

NORM

Normalizes the float in the F register.

OR m

Performs bitwise OR on the word at address m and the word in register A, storing the result in register A.

RD m

TODO

RMO r1,r2

Copies the value in register r1 into register r2.

RSUB

Returns from a subroutine by reading the value of L (set by JSUB) and setting PC to it, jumping back to where JSUB was called.

SHIFTL r1,n

TODO

SHIFTR r1,n

TODO

SIO

TODO

SSK m

TODO

STA m

TODO

STB m

TODO

STCH m

TODO

STF m

TODO

STI m

TODO

STL m

TODO

STS m

TODO

STSW m

TODO

STT m

TODO

STX m

TODO

SUB m

TODO

SUBF m

TODO

SUBR r1,r2

TODO

SVC n

TODO

TD m

TODO

TIO

TODO

TIX m

TODO

TIXR r1

TODO

WD m

TODO