Programming instructions

OCTAL

MNEMONIC CODE TIME

SYMBOL (BITS O-3)

(ec)

OPERATION

is2 Y 44 16 Index and Skip if Zero. The C(Y) are in-

cremented by one in 2’s complement

arithmetic. If the result is 0, the next

instruction is skipped. If not, the com-

puter proceeds to the next instruction.

The C(AC) are unaffected.

C(Y) + 1 => C(Y).

If result = 0, C(PC) + 1 => C(PC).

iv Y

jms Y 10

cal

xct Y

Jump to Y. The next instruction to be

executed is taken from memory cell Y.

Y => C(PC).

16 Jump to Subroutine. The C(PC) and the

C(L) are deposited in memory cell Y. The

next instruction is taken from cell Y + 1.

C(L) => C(Y,). 0 => C(Y,,).

C(PC) => C(Y&17). Y + 1 => C(PC).

16 Call Subroutine. The address portion of

this instruction is ignored. The action is

identical to jms 20. The instruction cal i is

equivalent to jms i 20.

8 + time Execute. The instruction in memory cell Y

of in-

will be executed. The computer will act as

struction if the instruction located in Y were in the

being place of the xct.

executed

AUGMENTED INSTRUCTIONS

None of the augmented instructions require a memory reference. Bits

4-17 of an augmented instruction are used to specify operations, many

of which may be combined in a single instruction. There are three classes

ot augmented instructions:

a. Operate class: includes o.perations on the AC and Link, the skip

group, and the halt instruction.

b. The special instruction, law.

c. Input-output transfer class: includes all the instructions which

initiate transfers of information between the Internal Processor and

an external device and those that sense the status of the devices.