Recent content by daver2

That error screen is main RAM (low bank of 16K). I will have a look at which bit/bits are at fault tomorrow morning. But you should also be able to do the same if you read my PETTESTER manual. Which pin of which IC was cleaned? Dave

Well, if you are having a problem with a video RAM this fault is also a possible problem with video RAM? I would have said the error screen in post #159 was main RAM and not video RAM though. I think you have IC socket problems to be honest. Dave

OK, so that fault is back again. Let's put that on a list of things to investigate later. I would now suggest removing the ROMulator and putting all of the correct ROMs in place. I would go with this as the EDIT ROM (to start with)...

So the character screen has both lower case and upper case characters displayed, and PETTESTER has passed the video testing. It makes no sense as to why the keyboard matrix display on the screen varies with the ROM 'f' being installed or not... Let me think about that one... With ROM 'f' in...

Excellent. Can you post a photograph of the PETTESTER screen when it is testing the ROM checksum and keyboard. I don't care where the 'f' ROM is located for this test. Dave

SH12 (schematic sheet 12) contains the circuit posted in #9. Dave

SH12 is schematic sheet number 12. It may be a typographical error though. What is: 1. The voltage across capacitor C11? 2. The voltage on the collector of transistor Q11 relative to 0V? Dave

And that image indicates a video circuit fault somewhere. Notice the absence of the uppercase letters (and there should be some associated symbols missing as well). This needs fixing before we start messing with the keyboard, as character codes may get converted by the fault into different...

With that setting, no 'standard' external ROMs are used (only internal ROMs). If you install a ROM with a hardware fault, this can mess the PET up for other reasons. There doesn't appear to be a switch setting on the ROMulator to disable the ROMularor ROMs in totality, unless setting an...

>>> It's like the rom is being intercepted by the romulator? Er, that's the whole point of the ROMulator, unless you switch the ROM mapping out 😉! This may account for why the 'n' EDIT ROM doesn't work as we expect... The idea of the ROMulator is that it ignores the external ROMs and replaces...

The table 'should' start at address $E6D1 in the machine. This should be at offset $06D1 into the EDIT ROM. You load the image file for the EDIT ROM into your EPROM reader/programmer and use the hex edit function of your EPROM reader/programmer to modify the bytes as required. You should then...

Thanks Robin. Let's see how many 'takers' we get. Dave

Fair enough, so this must be for a business keyboard. See http://www.zimmers.net/anonftp/pub/cbm/src/pet/pet_rom4_disassembly.txt And look for address E6D1. You will find the keyboard translation table for the business keyboard. There should be a match for the bytes from the business keyboard...

And yet the edit-4-80-n-50Hz.4016_to_8016.bin code did not work. Dave

So, to confirm, your physical PET keyboard is the GRAPHICS keyboard. Yes? But, when you press a key, you get the corresponding business keyboard code. Yes? Notice the row/col numbers on the post image above. Have you located the BASIC 4 disassembly on the zimmers website? Dave