Preliminary Specifications: Programmed Data Processor Model Three Part 2

The new C(AC) are the sum of C(Z) and the original C(AC). The C(Z) are unchanged. The addition is performed with 1's complement arithmetic.

If the sum exceeds the capacity of the Acc.u.mulator Register, the overflow flip-flop will be set (see Skip Group instructions).

_Subtract_ (10 usec.) sub x Y Operation Code 42

The new C(AC) are the original C(AC) minus the C(Z). The C(Z) are unchanged. The subtraction is performed using 1's complement arithmetic.

If the difference exceeds the capacity of the Acc.u.mulator, the overflow flip-flop will be set (see Skip Group instructions).

_Multiply_ (approximately 25 usec.) mul x Y Operation Code 54

The C(AC) are multiplied by the C(Z). The most significant digits of the product are left in the Acc.u.mulator and the least significant digits in the In-Out Register. The previous C(AC) are lost.

_Divide_ (approximately 90 usec.) div x Y Operation Code 56

The Acc.u.mulator and the In-Out Register together form a 70 bit dividend.

The high order part of the dividend is in the Acc.u.mulator. The low order part of the dividend is in the In-Out Register. The divisor is (Z).

Upon completion of the division, the quotient is in the In-Out Register.

The remainder is in the Acc.u.mulator. The sign of the remainder is the same as the sign of the dividend. If the dividend is larger than C(Z), the overflow flip-flop will be set and the division will not take place.

Logical Instructions

_Logical AND_ (10 usec.) and x Y Operation Code 02

The bits of C(Z) operate on the corresponding bits of the Acc.u.mulator to form the logical AND. The result is left in the Acc.u.mulator. The C(Z) are unaffected by this instruction.

Logical AND Function Table

AC Bit C(Z) Bit Result 0 0 0 0 1 0 1 0 0 1 1 1

_Exclusive OR_ (10 usec.) xor x Y Operation Code 06

The bits of C(Z) operate on the corresponding bits of the Acc.u.mulator to form the exclusive OR. The result is left in the Acc.u.mulator. The C(Z) are unaffected by this order.

Exclusive OR Table

AC Bit C(Z) Bit Result 0 0 0 0 1 1 1 0 1 1 1 0

_Inclusive OR_ (10 usec.) ior x Y Operation Code 04

The bits of C(Z) operate on the corresponding bits of the Acc.u.mulator to form the inclusive OR. The result is left in the Acc.u.mulator. The C(Z) are unaffected by this order.

Inclusive OR Table

AC Bit C(Z) Bit Result 0 0 0 0 1 1 1 0 1 1 1 1

General Instructions

_Load Acc.u.mulator_ (10 usec.) lac x Y Operation Code 20

The C(Z) are placed in the Acc.u.mulator. The C(Z) are unchanged. The original C(Z) are lost.

_Deposit Acc.u.mulator_ (10 usec.) dac x Y Operation Code 24

The C(AC) replace the C(Z) in the memory. The C(AC) are left unchanged by this instruction. The original C(Z) are lost.

_Deposit Address Part_ (10 usec.) dap x Y Operation Code 26

Octal digits 6 through 11 of the Acc.u.mulator replace the corresponding digits of memory register Z.

C(AC) are unchanged as are the contents of octal digits 0 through 5 of Z. The original contents of octal digits 6 through 11 of Z are lost.

_Deposit Instruction Part_ (10 usec.) dip x Y Operation Code 30

Octal digits 0 through 5 of the Acc.u.mulator replace the corresponding digits of memory register Z. The Acc.u.mulator is unchanged as are digits 6 through 11 of Z. The original contents of octal digits 0 through 5 of Z are lost.

_Load In-Out Register_ (10 usec.) lio x Y Operation Code 22

The C(Z) are placed in the In-Out Register. C(Z) are unchanged. The original C(IO) are lost.

_Deposit In-Out Register_ (10 usec.) dio x Y Operation Code 32

The C(IO) replace the C(Z) in memory. The C(IO) are unaffected by this instruction. The original C(Z) are lost.

_Jump_ (5 usec.) jmp x Y Operation Code 60

The Program Counter is reset to address Z. The next instruction that will be executed will be taken from memory register Z. The original contents of the Program Counter are lost.

_Jump and Save Program Counter_ (5 usec.) jsp x Y Operation Code 62

The contents of the Program Counter are transferred to the Index Adder.

When the transfer takes place, the Program Counter holds the address of the instruction following the jsp. The Program Counter is then reset to address Z. The next instruction that will be executed will be taken from memory register Z.

_Skip if Acc.u.mulator and Z differ_ (10 usec.) sad x Y Operation Code 50

The C(Z) are compared with the C(AC). If the two numbers are different, the Program Counter is indexed one extra position and the next instruction in the sequence is skipped. The C(AC) and the C(Z) are unaffected by this operation.

_Skip if Acc.u.mulator and Z are the same_ (10 usec.) sas x Y Operation Code 52

The C(Z) are compared with C(AC). If the two numbers are identical, the Program Counter is indexed one extra position and the next instruction in the sequence is skipped. The C(AC) and C(Z) are unaffected by this operation.

Non-Indexable Memory Instructions

These instructions have the same word format as the indexable instructions. Since they operate on the index register location, x, they cannot be indexed.

_Skip on Negative index_ (10 usec.) snx x Y Operation Code 46