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Author Topic: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.  (Read 638 times)

rayarachelian

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    • LisaEm
Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #60 on: June 15, 2021, 04:03:23 pm »

Quote
If you have a large logic analyzer it may help you debug futher
I have a USB logic analyzer, but the vast amount of data that it produces when connected to the Lisa makes it impossible to go through it all. The text and CSV files that it outputs are so large that I can't open them in any program without it crashing.

Yeah, those HP ones understand 650x and 68000 busses and can show you what the CPU is doing, what address it accesses, read/write and value and timing.
With a USB one, you'd need specialized software to analyze it.
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AlexTheCat123

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #61 on: Yesterday at 10:00:40 am »

So I played around with the logic analyser some more and it revealed something interesting. I hooked it up to the BD0-BD7 lines as well as the address lines A1-A7 that feed into the muxes that allow the CPU to access the shared floppy RAM. I also connected it to the select signal (S) on the muxes so that I can see when they're allowing the CPU to address the floppy RAM. I then went into service mode and tried to read the I/O ROM version number from location FCC031. Interestingly, every time it successfully read the version number, the select signal went low and stayed low for around 600ns, but each time it failed the select signal only stayed low for around 100ns. You can see this behavior in the two screenshots that I've attached. What could be causing this?
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rayarachelian

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #62 on: Yesterday at 02:48:37 pm »

So I played around with the logic analyser some more and it revealed something interesting. I hooked it up to the BD0-BD7 lines as well as the address lines A1-A7 that feed into the muxes that allow the CPU to access the shared floppy RAM. I also connected it to the select signal (S) on the muxes so that I can see when they're allowing the CPU to address the floppy RAM. I then went into service mode and tried to read the I/O ROM version number from location FCC031. Interestingly, every time it successfully read the version number, the select signal went low and stayed low for around 600ns, but each time it failed the select signal only stayed low for around 100ns. You can see this behavior in the two screenshots that I've attached. What could be causing this?

Looking at: https://lisaem.sunder.net/LisaSchem/Lisa1SysIO4.gif

By Select you mean !CS on pin 8 of the two SRAMs, yes?

Could be R28 (s/b 47Ohm) or U4C LS157 pin 12 (4Y), or it's input lines 4A, 4B.  4A should go to ground, so that's easy to check.

4B goes to Y0 of U5A S139, so one of it's inputs could be the cause.

That could be the XNOR S02 gate at U8A (pin 10), A11, A12 of the 6504, but likely these aren't it as those come from the 6504 itself.

There's also some fun components in the center left of the schematic, right under the SRAMs, there's a transistor Q7 with 3 resistors going to capacitor 28.
Not sure if those can pull down the signal or mess with it, doesn't look like it, but who knows, if they're messed up in some way they might.
(R54 is acting as a pullup from the looks of it, and R26 too)
« Last Edit: Yesterday at 02:55:53 pm by rayarachelian »
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Lisa2

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #63 on: Yesterday at 05:27:14 pm »

Guys,
Just to clarify, the drawing that Ray linked is actually the 2/10 I/O board with the IWM chip.

I have attached the correct drawing for the 2/5 I/O board.

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rayarachelian

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #64 on: Yesterday at 06:08:51 pm »

Just to clarify, the drawing that Ray linked is actually the 2/10 I/O board with the IWM chip.
I have attached the correct drawing for the 2/5 I/O board.

D'Oh! Thanks for that. That came from here: https://lisaem.sunder.net/cgi-bin/bookview2.cgi?zoom=0?page=8?book=6?Go=Go and is labeled "Lisa 1 I/O Board 4" - are the ones labeled "Lisa210Sys" swapped with the "Lisa1" ones?
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When you tear out a man's tongue, you are not proving him a liar, you're only telling the world that you fear what he might say. - GRRM

AlexTheCat123

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #65 on: Yesterday at 06:52:37 pm »

Quote
By Select you mean !CS on pin 8 of the two SRAMs, yes?

No. I'm talking about the S signal that feeds into the three LS157 muxes that select between the shared RAM being addressed by the 68000 and the RAM being addressed by the 6504.

The /DTACK signal that comes out of the 8T97 on the schematic also seems to suffer from the same problem where it goes low for a much shorter period of time when the Lisa fails to properly access the shared RAM compared to when it succeeds.
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Lisa2

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Re: Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
« Reply #66 on: Yesterday at 08:35:28 pm »

D'Oh! Thanks for that. That came from here: https://lisaem.sunder.net/cgi-bin/bookview2.cgi?zoom=0?page=8?book=6?Go=Go and is labeled "Lisa 1 I/O Board 4" - are the ones labeled "Lisa210Sys" swapped with the "Lisa1" ones?
I/O sheet four for both the 2/5 and 2/10 appear to be the same on the sunder site....
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