BBL

Name

Load Accumulator Immediate

Function

The 4 bits of data, DDDD stored in the OPA field of the insruction word | br| are loaded into the accumulator. The previous contents of the acummulator | br | are lost. The carry/link bit is unaffected.

Syntax

LDM(D)

Assembled

Binary

1101 DDDD

Decimal

192, then incrementing by 1 until 207 (1st word).

Hexadecimal

0xC0, then incrementing by 1 until 0xCF (1st word).

Symbolic

 ../../_images/ldm-sym.png

Execution

1 word, 8-bit code and an execution time of 10.3 \({\mu}\) sec

Side-effects

Not Applicable

Implemented

bbl

Detailed Description

The program counter (address stack) is pushed down one level. Program control transfers to the next instruction following the last jump to subroutine (JMS) instruction.

The 4 bits of data DDDD stored in the OPA portion of the instruction are loaded to the accumulator.

BBL is used to return from a subroutine to main program. The carry bit is not affected.

../../_images/bbl.png

Note

In the example here, the BBL instruction loads the value 6 into the accumulator. The address 013 is read into the program counter, and program execution proceeds with the XCH instruction.