Recent content by Ruud

Not my discovery but read in MSBIO1.ASM from line 82 on how MS thought about IBM :)

I love the socket on the back! :) I'm familiar with C13 sockets at the back but a normal household socket?

I only just saw that post, must have missed that for one or another reason. My apologies. In the mean time I found some 6502 sources that either displayed 24 or 25 lines on the screen. And I found a datasheet of the 6845 giving the parameters for PAL and NTSC. So I'm learning every day.

Thank you!

Aha, THAT makes sense! Now I have a solid base to figure out the rest. Thank you very much!

MDA = Monochrome Display Adapter, CGA = Color Graphics Adapter. Two complete different cards and monitors, knowing that for already 39 years.

OK, maybe I was not clear enough: why the differences in parameters for CGA text and graphics? NOT about the differences between MDA end CGA, that is clear enough. In the case of my friend it didn't work out that way. I remember having seen parameters for a Hercules-clone card for the graphical...

A friend of mine mentioned that MDA mode worked on his monitor but graphical mode didn't. I always thought that the only difference between MDA and graphical mode was that in MDA mode the pixels were generated by ROM in graphical mode by RAM. Same for CGA text an graphical mode. But having a...

In 1989 I created my own 6502 assembler and disassembler. In time I expanded it with other 65xxx products, the Z80 and 6800. Lately I added the 6809. Disassembling a bit of 6809 code and assembling it again, I found a difference. The cause was an error in both the assembler and disassembler, a...

I can only say: WOW! Question out of curiosity: why did you use a VGA card and not a CGA or MDA card? When running the VGA-BIOS, you could have run into a bug activated by the software and a POST card would not be helpful here. Possible answer: you don't have such a card and monitor?

Define "usable" first. I would start replacing these chips and preferably ones that have been tested on another board. If possible, let the board run at 6 MHz to avoid possible speed problems when running at 10 MHz. If one of the chips was indeed the culprit, you'll have a usable board again...

Oops, boot manager of course.

Thank you for the explanation!

I don't know IcarOS (Google let me to fitness machines) so I don't know if that order of installing the OSes will work. If it won't, use a boor manager.

And what was the problem? AFAIR I always used a third party MDA card so I never encountered the bug. I just checked my old sources and outputting 00 is the first thing RDR does at a reset, after executing CLI. So I really, really wonder.