Recent content by Nivag Swerdna

Lots of knobs to twiddle... DC coupled should work... these signals have a common ground. Select DUAL... use position to put CH1 in top half of screen... use position to put CH2 in bottom half... use Volts/Div to make them fit in their sections of the screen Looking forward to seeing some...

Zoom out slightly (i.e. change timebase) so you see a full cycle (and a bit), then move it down to the bottom half of the display and then get working on adding CH1 (and move the CH1 trace into the top half). We are aiming for two traces... one in the top half and one in the bottom. PS I am...

Set the TRIGGER to CH2 (slide switch on right) Set -ve edge Adjust trigger level. I am only guessing from the picture as I don't have a manual for this device... I'm not sure what "TRIG ALT" does! try on and off!... Also not sure about "AUTO" versus "NORM"! Just fiddle around with the...

Use 2 channels. Two lines... it will be very interesting.

A simpler approach is to simply use CH2. Put the CH2 probe on BA15. Adjust the timebase to one cycle of BA15 fits. Move the Trigger to CH2 and use the -ve edge mode, then adjust the trigger level until everything stops moving. IMHO Two channels is enough for all this. All the probing for...

Likewise I use edge pins on my adapters rather than using turned pins... https://www.tindie.com/products/nivagswedna/replacement-pet-rom-6540-pre-programmed/ In fact I use the same ones D'Asaro used.

In what sense? Did you measure the frequencies? what were they? I think you really need to post a picture for EACH one in turn.

It is true that the outputs of B3 and C3 do drive the memory expansion connector but they also drive the address bus across the board. It might not be obvious but B3 and C3 are just buffers that help the 6502 drive the various downstream devices (including those beyond the expansion connector)...

Now you mention it... I'm not sure... I cannot see the chip numbers in the first image... too blurred.

In Post #1 if you squint you can read... ### COMMODORE BASIC ### 7167 Bytes Free So this PET is almost working already. The issue seems to be in the video generation only (since it can clearly write to 8000- since that's where the message comes from) Is the screen static or changing? Maybe...

Indeed. Back in the early days the machine was almost working. I feel that new faults are being introduced all the time so we probably now have some broken traces and/or shorts added into the mix.

That's not good. D2 Pins 20, 21, 22, 23, 9 and 17? PS I have no idea of your current configuration but it should have a 6502 correctly orientated in the CPU socket and the 6520 PIAs x2 and 6522 VIA removed.

It is fine. When placed in D9 it should produce a scrambled screen with the first character rapidly alternating between 00 and FF. Works in VICE @Desperado Can you put your logic probe on pin 8, 9 and 20 of D9 please?

I'm thinking about offering a repair service for your board... Send me a message if you are interested and I will reply with terms.

Can I recommend using the abracadabra.bin (contained in the .zip) from Post # 519 ? Earlier Post #519 This is a 4K Image that is to be burnt into a ROM to replace the Kernel. It writes to and reads from video memory which is what I think you are trying to currently achieve?