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Just got a Tek 2465A, couple questions (how I screwed the calibration data)!!

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MarkL:
Thanks for the data usuthu65, and for transcribing it alpher.

I still can't get the checksum to match.  Maybe I'm looking at dead code in the EPROM and the firmware is using a different subroutine.

Although it's out of the block for the checksum (0B to AA), there is one error in the transcription that I found.  Exerciser location ED is 9186 (not 918F).

The parity on locations 01 to 6E is good.

alpher:
Thanks Mark, appreciate you catching my mistake. :)
I will try to program the sram tonite, worse come to worst I'll just change it to dallas chip and be over with it.
I've edited my previous post with the correct ED value both in the listing and the included bin file.
Just a thought, maybe your firmware dump doesn't match the ram ( i.e. is from different revision or something) ?
Would you like me to post a firmware dump from my scope?

MarkL:

--- Quote from: alpher on March 29, 2018, 05:22:37 pm ---...
Just a thought, maybe your firmware dump doesn't match the ram ( i.e. is from different revision or something) ?
Would you like me to post a firmware dump from my scope?

--- End quote ---
That's always possible.  If you want to post it, I'll see if I can locate the checksum routine in it.  But without an actual 2465A and logic analyzer in front of me it's impossible to say what it's really doing.

Since you have an EPROM burner, it should also be possible to burn a little program in a spare EPROM that just writes the 512 bytes to the SRAM at 0x1E00.  Unplug the real EPROM, plug in the SRAM restorer, power it up for a moment, and then put the real EPROM back.

I can look at hacking together an EPROM image if you want to try it.  Or if you know 6800 assembly, go for it.  Just look out for the 2465A memory mapping.  It's bank switched.

alpher:

--- Quote from: MarkL on March 29, 2018, 07:33:56 pm ---
--- Quote from: alpher on March 29, 2018, 05:22:37 pm ---...
Just a thought, maybe your firmware dump doesn't match the ram ( i.e. is from different revision or something) ?
Would you like me to post a firmware dump from my scope?

--- End quote ---
That's always possible.  If you want to post it, I'll see if I can locate the checksum routine in it.  But without an actual 2465A and logic analyzer in front of me it's impossible to say what it's really doing.

Since you have an EPROM burner, it should also be possible to burn a little program in a spare EPROM that just writes the 512 bytes to the SRAM at 0x1E00.  Unplug the real EPROM, plug in the SRAM restorer, power it up for a moment, and then put the real EPROM back.

I can look at hacking together an EPROM image if you want to try it.  Or if you know 6800 assembly, go for it.  Just look out for the 2465A memory mapping.  It's bank switched.

--- End quote ---

Ilike the SRAM restorer idea quite a bit, unfortunately my assembly skills are, how should I put it, nex to nill.
Last time I coded anything was a looong time ago.  :) :) :)
If you wouldn't ming posting an image though I have plenty of spare EEPROMs.

MarkL:

--- Quote from: alpher on March 29, 2018, 07:57:24 pm ---...
If you wouldn't ming posting an image though I have plenty of spare EEPROMs.

--- End quote ---
Ok, here you go.  It should be writing usuthu65's data.

I don't know if it should go in U2160 or U2260 because I don't know which EPROM is selected at boot time by PAL U2250.  I guess try U2160 first.

It won't blink lights or anything.  If I got at least some of it right U2310 pin 12 should go high since that enables the SRAM.

I'm flying totally blind here.  I can't test it.

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