WRR

Name

Write ROM Port

Function

Write to a specified ROM port

Syntax

WRR

Assembled

Binary

11100010

Decimal

226

Hexadecimal

0xE2

Symbolic

 ../../_images/wrr-sym.png

Execution

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

Side-effects

Not Applicable

Implemented

wrr

Detailed Description

The content of the accumulator is transferred to the ROM output port of the previously selected ROM chip. The data is available on the output pins until a new WRR is executed on the same chip. The LSB bit of the accumulator appears on I/O 0, (pin 16), of the 4001.

No operation is performed on I/O lines coded as inputs.

The carry bit and the accumulator are unchanged.

The opcode for this instruction does not contain any additional data:

../../_images/wrr.png

Example Program

The example program will write the value 15 to the output port associated with the ROM chip 2.

/ Example program
      FIM        4P  64
      SRC        4P
      LDM        15
      WRR