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Old 20th Mar 2021, 7:29 pm   #1181
ScottishColin
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Default Re: Non-working Commodore PET 3016

Is this OK? Pin 8 yellow, pin 9 green.

Colin.


Quote:
Originally Posted by SiriusHardware View Post
Yes, what Julie said?

If there is now activity on UB2 pin 8, could you capture UB2 pin 9 (one whole cycle of that waveform) along with UB2 pin 8 so we can see if we are now getting BANK SEL for the first quarter of the sweep. (This is with the NOP device in).

If still no activity on UB2 pin 8, hold fire and just report back.
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Old 20th Mar 2021, 7:38 pm   #1182
SiriusHardware
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Default Re: Non-working Commodore PET 3016

That is PERFECT and shows that replacing UB2 has fixed the missing BANK SEL signal. So now we have to find the next broken bit, I need to ask you to revisit UG7.

Can you have a look at UG7 pin 11, turn the horizontal trace speed up until you have one cycle of that waveform on the screen, and at the same time capture whatever is coming out of UG7 pin 8.
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Old 20th Mar 2021, 7:42 pm   #1183
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Default Re: Non-working Commodore PET 3016

UB2-8 looks good.

Now need to check RAS and CAS again. UH1-6, UH1-8, UG1-11, UG7-6, UG7-12

Note the two different sources for RAS, one is for refresh, the other for read and write for bank selected.
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Old 20th Mar 2021, 7:45 pm   #1184
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Default Re: Non-working Commodore PET 3016

I thought we'd better look for the RAM buffer read enable signal as well.
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Old 20th Mar 2021, 7:49 pm   #1185
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Default Re: Non-working Commodore PET 3016

Here you go. UG7 11 yellow, 8 green.

Colin.


Quote:
Originally Posted by SiriusHardware View Post
That is PERFECT and shows that replacing UB2 has fixed the missing BANK SEL signal. So now we have to find the next broken bit, I need to ask you to revisit UG7.

Can you have a look at UG7 pin 11, turn the horizontal trace speed up until you have one cycle of that waveform on the screen, and at the same time capture whatever is coming out of UG7 pin 8.
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Old 20th Mar 2021, 7:54 pm   #1186
SiriusHardware
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Default Re: Non-working Commodore PET 3016

We have a read enable signal on the RAM buffer although I think I expected it to be a series of short pulses, not a steady low like that.

Can you do the ones Mark mentioned, and then I have another one in the queue.
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Old 20th Mar 2021, 7:58 pm   #1187
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Default Re: Non-working Commodore PET 3016

After you've done Mark's checks could you let us see UG7 pin 11 (one complete cycle as before) and this time UG7 pin 9 on the other trace.
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Old 20th Mar 2021, 8:00 pm   #1188
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Default Re: Non-working Commodore PET 3016

Quote:
Originally Posted by SiriusHardware View Post
We have a read enable signal on the RAM buffer although I think I expected it to be a series of short pulses, not a steady low like that.
This could be due to low sample rate, verify UG7-8 at faster sample rate, maybe 10us per division.

Edit: Ignore this, I think it should be steady low.
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Old 20th Mar 2021, 8:02 pm   #1189
SiriusHardware
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Default Re: Non-working Commodore PET 3016

I hope you're right, I would have expected it to score a few random hits though. Thinking possibly buffered R/W (UG7 pin 9) may be constantly high, which it should not be of course. Or shouldn't it? That's the default state for the R/W line when it is not writing. We have the CPU locked in read mode while doing the NOP test, so R/W steady high (therefore UG7 (8) steady low) may actually be OK.
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Old 20th Mar 2021, 8:05 pm   #1190
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Default Re: Non-working Commodore PET 3016

Quote:
Originally Posted by SiriusHardware View Post
After you've done Mark's checks could you let us see UG7 pin 11 (one complete cycle as before) and this time UG7 pin 9 on the other trace.
UG7-9 should be steady high while running NOP test.
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Old 20th Mar 2021, 8:08 pm   #1191
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Default Re: Non-working Commodore PET 3016

Attached. UG7/6 and UG7/12 'pulsed' between high and waves - I've tried to show what my scope shows with the attached files.

Colin.


Quote:
Originally Posted by Mark1960 View Post
UB2-8 looks good.

Now need to check RAS and CAS again. UH1-6, UH1-8, UG1-11, UG7-6, UG7-12

Note the two different sources for RAS, one is for refresh, the other for read and write for bank selected.
Attached Thumbnails
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Name:	UH1-6 20210320.jpg
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Size:	41.6 KB
ID:	229683   Click image for larger version

Name:	UH1-8 20210320.jpg
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ID:	229684   Click image for larger version

Name:	UG1-11 20210320.jpg
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ID:	229685   Click image for larger version

Name:	UG7-6 1 of 2 20210320.jpg
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ID:	229686   Click image for larger version

Name:	UG7-6 2 of 2 20210320.jpg
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Size:	42.9 KB
ID:	229687  

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Old 20th Mar 2021, 8:08 pm   #1192
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Default Re: Non-working Commodore PET 3016

UG7/12 attached.

Colin.


Quote:
Originally Posted by Mark1960 View Post
UB2-8 looks good.

Now need to check RAS and CAS again. UH1-6, UH1-8, UG1-11, UG7-6, UG7-12

Note the two different sources for RAS, one is for refresh, the other for read and write for bank selected.
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Name:	UG7-12 20210320.jpg
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Old 20th Mar 2021, 8:09 pm   #1193
SiriusHardware
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Default Re: Non-working Commodore PET 3016

Quote:
Originally Posted by Mark1960 View Post

UG7-9 should be steady high while running NOP test.
Yep, I just talked myself around to that point of view.
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Old 20th Mar 2021, 8:10 pm   #1194
ScottishColin
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Default Re: Non-working Commodore PET 3016

Confirmed steady high - measured at 5.3V with a meter.

Colin.


Quote:
Originally Posted by Mark1960 View Post
Quote:
Originally Posted by SiriusHardware View Post
After you've done Mark's checks could you let us see UG7 pin 11 (one complete cycle as before) and this time UG7 pin 9 on the other trace.
UG7-9 should be steady high while running NOP test.
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Old 20th Mar 2021, 8:18 pm   #1195
SiriusHardware
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Default Re: Non-working Commodore PET 3016

The intermittent nature of the signal you had in #1191 was down to the fact that those signals are probably (intentionally) only active for part of the address sweep. I think that's more activity than we had before though?
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Old 20th Mar 2021, 8:26 pm   #1196
Mark1960
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Default Re: Non-working Commodore PET 3016

From #1191 and #1192, CAS0 and CAS1 look correct.

But nothing on RAS0.

Check UH1-3 and UH1-1, both together if possible.

Also UH1-11 and UH1-13.
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Old 20th Mar 2021, 8:28 pm   #1197
ScottishColin
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Default Re: Non-working Commodore PET 3016

I've had a quick look and I don't think I've looked at those pins before?

Colin.


Quote:
Originally Posted by SiriusHardware View Post
The intermittent nature of the signal you had in #1191 was down to the fact that those signals are probably (intentionally) only active for part of the address sweep. I think that's more activity than we had before though?
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Old 20th Mar 2021, 8:31 pm   #1198
SiriusHardware
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Default Re: Non-working Commodore PET 3016

Maybe not those pins, but those signals, probably at the RAM end the last time we looked.

Added to Mark's checks in #1196, can we also see

UH1 (8) and UH1 (6) both at the same time as well please.
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Old 20th Mar 2021, 8:34 pm   #1199
ScottishColin
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Default Re: Non-working Commodore PET 3016

Attached.

Note UH1-3 was also alternating between the waves shown and a high reading.

Colin.


Quote:
Originally Posted by Mark1960 View Post
From #1191 and #1192, CAS0 and CAS1 look correct.

But nothing on RAS0.

Check UH1-3 and UH1-1, both together if possible.

Also UH1-11 and UH1-13.
Attached Thumbnails
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Name:	UH1-1 yelloe UH1-3 green 20210320.jpg
Views:	13
Size:	51.1 KB
ID:	229690   Click image for larger version

Name:	UH1-11 yellow and UH1-13 green 20210320.jpg
Views:	13
Size:	51.9 KB
ID:	229691  
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Old 20th Mar 2021, 8:37 pm   #1200
ScottishColin
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Default Re: Non-working Commodore PET 3016

Less to see on this one...

Colin.


Quote:
Originally Posted by SiriusHardware View Post
Maybe not those pins, but those signals, probably at the RAM end the last time we looked.

Added to Mark's checks in #1196, can we also see

UH1 (8) and UH1 (6) both at the same time as well please.
Attached Thumbnails
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Name:	UH1-6 yellow UH1-8 green 20210320.jpg
Views:	14
Size:	41.5 KB
ID:	229692  
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