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.
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...
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...
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)...
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...
That's not good.
D2 Pins 20, 21, 22, 23, 9 and 17?
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?
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?
To be fair this is quite long in the tooth now. It is the scope I wished I had bought... I actually bought a DS1052 before the 1054 came out and regret having only 2 channels. The critism of memory depth etc are also very valid but there is an assumption that for hobby use any...
Buy a logic probe, should be under $20
>>> FLAMEPROOF_UNDERWEAR ON
Don't buy a crappy old analogue scope... just don't do it.
If you have budget buy a 4CH Rigol DS1054Z
If you don't have budget then stick with the logic probe and possibly add a cheapo clone 8CH logic analyser from ebay
You know I have never actually dedicated many brain cycles to the implementation of a NOP adapter but I guess on reflection there are essentially two ways of doing it...
1. Force the data bus to EA
2. Disconnect the data pins at the CPU and force these to EA. The data bus itself is now...
Told ya! Easy to do.
FWIW my RAM solution... https://www.tindie.com/products/nivagswedna/pet-8k-ram-replacement-for-6550-pet-2001s/
The secret to SMD soldering is.... magnification... I have a widefield microscope but multiple pairs of +2 glasses also works!