MacGyverr's latest activity

Good. Suggesting to me that you did the +5V verification that I suggested. And let's see what remains after U13 replacement. There...

So after about 2 hours of me working to remove and replace that failed 8255, it finally works correctly. It correctly shows all RAM...

There should not be a problem using that chip. In my opinion, use of an IC socket is prudent. The "10" is pointing to the 4K block at...

So I got the replacement 8255 in the mail a D8255AC-2, the original was a P8255A-5 just want to confirm it is a proper replacement...

I ordered a replacement desoldering gun (a Hakko FR301-03/P clone that doesn't use a bouncing solenoid), if you think those TMS2114-20NL...

I did that. I am very confident, based on the circuit, and an experiment that I did, that U13 and U15 are for the top 'half' of the...

Was going to buy a few of these TMS2114-20NL 200ns replacements and try to fix the RAM, but found a replacement (untested so I may be...

Further regarding the unexpected characters on the IBM MDA. Looking at the circuit diagram more: U12 and U13: Character - bits 7 to 4...

Related are posts #7 and #8 in the thread at [here]. There, the change of a space (20h) to an exclamation mark (21h) is a change of bit...

Well, it's got all new caps anyway now. :) I guess I'll have to pull the RDR to test it, thanks for keeping RDR updated BTW. Knowing...

Very very recently, it was discovered that in the last 8 versions of RDR, a bug existed that made RDR incompatible with the 'IBM...

I tried using the MDA/parallel card instead of the CGA card and composite, the MDA doesn't trip the power supply protection (5 and 12...

Correct (for a multimeter in voltage mode). The active thread at [here] may assist you. Well, PC2, which corresponds to SW2-3. RDR...

Did the tests: All switches off = 00000 Grounded PC0 = 10001 Grounded PC1 = 01000 Grounded PC2 = 00000 Grounded PC3 = 00010 Every pin...

Upon closer inspection it's booting into RDR, but my CGA card seems to be scrolling just really fast and skewed (on the composite out, I...