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I think this is the protocol for how my PIA interacts with the keyboard as well :)

Thanks. All ROM check sums and RAM reads OK. If I switch my romulator to basic 2 (at least on.my last test) it starts up but all the keys are mis matched (many return nothing). I think this weekend is new socket time for a starter. I really wanted to keep the white sockets because of the look...

Update on progress. I had a fleck of conductive paint causing the P key to hold. Cleaned that up. Was running fine and with SD card loading software for about 3 hrs, then had some odd faults which I thought was just a game bug. Initially characters were coming out random when I typed (many keys...

Yep that's what I thought. There seems to be no continuity on the P contacts when sign a multi meter in the key or though pins E&4 on the keyboard connector. Got me flummoxed so I'm going to stop and try testing again as logically it must be the keyboard shorting and generating the signal.

Yep ran with pet tester , it's showing P key i.e $50 on byte 4(ish). So further wierdness. If I disconnect the keyboard pet tester gives all 0's. If I just plug in the keybaord PCB, i.e no keys it gives $50 for a P key as if they key is pressed. On reassembly if I hold L and Runstop then the P...

So my next escapade. I replaced the w65c21S with a W65c21N. Still gives a capital P on every keyboard press (as before when it starts up a P appears as well) really weird issue. Stumped if I know how to diagnose this. I assume it's causing some interaction with the keyboard via with causing the...

Hi, so story so far a 6522 was definitely bad so swapped out that one with a WC6522N 6520 is suspect as the basic diagnostic code showed the ATN etc are failing test. Tried a w65c21S, definitely didn't work seemed to be injecting P character Infront of every character I typed so I guess it's...

Thanks. The edge connector is nice an clean so I'll have a hunt for the test program next :)

Hi so my pet is up and running now (3016 upgraded to a 3032 with basic 4.0) I've just plugged in an sd2 pet from tfw8b. What I get when trying to do a load"WEDGE",8,1 is a file not found error. Running directory reports as if there are no filles. Trying a load"*",8 gives the file not found...

Hi it's a uveprom. It's odd they just own byte is damaged and it looks like only a jump when handling a syntax error. Perhaps it was burnt wrong and never noticed

It's doesn't look too bad, you pretty much have consistent values just matching them up to the hex values to check the data lines are good. Do what I did, have a day off, let it process in your head then go back to it. It was reading through this thread that got me to the point where I could...

It's ud7. It checksums to A42d instead of A425 Byte at $0809 is $06 instead of $00 Looking at the binary I think this is jmp $BF08 instead of jump $BF00 based on the disassembly . Bf00 is the syntax error routine. Bf08 would be jumping into the not function. The routine at D804 is used by...

Hi. Just on that note about the RAS signal. What got me there was doing an oscilloscope trace in both H1 pin6 and G1 pin 13. They looked different initially and degraded later to no signal on G1. There are a couple of vias on the way so it may be worth tracing. What I found was G1 pin 12 gives a...

Thanks. I forgot to say as well. The basic 4 eeprom I have varies by one byte from the normal one. On a brief look at it I think it may be a patch rather than faulty. I'd check my dump tonight and see if I can disassemble around the difference.

Thanks. I'll take a couple of days off as I have to brace myself for the floppy drive. That at least looks like a zero page ram fault.

And to quote an old Sepultura song " Under a pale grey sky he shall arise" The pet is past the rams screen. Fault were - one of the H1 flip flops was bad replaced The signal going from h1 pin 6 was good. Receiving at G1 pin 13 as random between a bad saw tooth wave and just low on different...

As a follow up. I was being a dumbass. I didn't even notice that one of the 244 buffers had lifted itself out the socket with me rotating the board etc. So reseated that and I'm back to the usual $FF screen. Following the traces, I can see the not Q (H1 pin 6) making a nice pair of pulses...

Hi, I think post end of day I was having a typo session. As G1 pins are 11 12 and 13 for the logic gate. I'll do another probe. I wanted to get a photo of the oscilloscope but I need a third hand for that :) Looking at the datasheet for the s74 Vs ls74, the pulse turn is 6ns Vs 20ns so it may...

Sorry my typo it's pin6. I put in a 74ls74 under the assumption that is was compatible with a 74s74 (i.e. it's the lower power version). I'm going to get bmy desoldering gun out tomorrow and remove the sockets and check for shorts. I suspect I have a possible bridge under the socket.

Actually after some probing and checking signals I get some rotating garbage on test as per screen shots as an example. It looks like zero page is fairly static but the upper 512 bytes cycle. What I see on H1 pin 16 looks like it's going from 2.5v to 5v rather than 0 to 5 in a pulse (I need to...