UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

SiriusHardware · 9th Apr 2019, 8:12 pm

A quick test for the I/O section of the INS8154 IC just using the monitor - assuming the new / improved monitor is in use.

First,

Code:

Abort
0 8 2 3
Term
F F
Mem

You won't see the data digits change, but doing this writes FF to the port 'B' data direction register to define all of the port B pins as outputs.

Then,

Code:

Abort
0 8 2 1
Term
5 5
Mem

This time, you will see the data digits change. This writes the pattern 01010101 to the port pins 0-7 of port B. You should be able to verify this with a meter, scope or logic probe.

Finally,

Code:

Abort
0 8 2 1
Term
A A
Mem

Should write the pattern 10101010 to bits 0-7 of port B.

I chose port B for this because the port pins 0 through to 4 appear in a sensible order on the edge connector. The port A pins are all over the place.

9th Apr 2019, 8:12 pm	#156
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,567	Re: MK14 schematic revisions A quick test for the I/O section of the INS8154 IC just using the monitor - assuming the new / improved monitor is in use. First, Code: Abort 0 8 2 3 Term F F Mem You won't see the data digits change, but doing this writes FF to the port 'B' data direction register to define all of the port B pins as outputs. Then, Code: Abort 0 8 2 1 Term 5 5 Mem This time, you will see the data digits change. This writes the pattern 01010101 to the port pins 0-7 of port B. You should be able to verify this with a meter, scope or logic probe. Finally, Code: Abort 0 8 2 1 Term A A Mem Should write the pattern 10101010 to bits 0-7 of port B. I chose port B for this because the port pins 0 through to 4 appear in a sensible order on the edge connector. The port A pins are all over the place.