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

acollins22 · 25th Oct 2017, 8:38 pm

Hi folks,

Thanks to julie_m's suggestion I have more information.

I wrote a small piece of code as suggested that tried to write to an I/O port and loop around. When this is running I can see activity on the _IOREQ_ line.

Just for the sake of control I did the same test with the screen filling code and didn't see any activity on the _IOREQ_ line.

This suggests to me that the code must be executing which in turn suggests that the ROM is being read and the CPU is running.

Yea!

Thanks everyone.

Andy.

25th Oct 2017, 8:38 pm	#12
acollins22 Pentode Join Date: Oct 2010 Location: Melton Mowbray, Leicestershire, UK. Posts: 156	Re: Nascom repair - Looking for clues please Hi folks, Thanks to julie_m's suggestion I have more information. I wrote a small piece of code as suggested that tried to write to an I/O port and loop around. When this is running I can see activity on the _IOREQ_ line. Just for the sake of control I did the same test with the screen filling code and didn't see any activity on the _IOREQ_ line. This suggests to me that the code must be executing which in turn suggests that the ROM is being read and the CPU is running. Yea! Thanks everyone. Andy.