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OK. The difference between S-records, which are text, is that each record (basically each line in the file) can specify the address that the data following on that line should be programmed to. This

Yes! I see that now and miss the connection off-sheet that I was looking at. It does meet up with P503, which jumpers to 5V, via 10K, and that appears to just be a pull-up on that net.

Hi Chris, I have the XGecu T48 programmer. Sorry, I have no idea what s-record format is or if my programmer is able to accept that format. I did a google search and came up with nothing and the

Hey Guys, back on the case here for a bit. Excellent news that you can burn the EPROMs yourself Don. That will give us much shorter turn-around from code to test ;-) Can your EPROM programmer accept

Hi Chris, The A15 pin for the EPROMS is not tied high, but rather is tied directly to the output of the PAGE SELECT bit of a 74LS174 latch. The PAGE SELECT bit of the register determines whether the

Hi Chuck, That's terrific! my 2467B's SN is also in the 10K range.? I will be watching this space with great interest! Don

Hi Chris, As it happens, I found a 2467B with SN in the 10K range on my shelves... Just like Don's scope! I bet you didn't see that one coming ;-) I sure didn't. I pulled U2160 and U2260, and took a

Chris, Thanks for the offer to send me a programmed 27512. However, that may not be necessary (at least not just yet). I have an EPROM programmer and a? couple of Winbond W27C512 EEPROMs which I have

Actually, on second thought, I don't think we need to do this. I believe the schematic, at least for 2465A and 2467, shows line A15 going into both of the 27512 EPROMS being tied high. That's via this

Right-- so, the theory is that U2260 is the "upper half" of the program space and therefore contains the reset and other interrupt vectors at the end. So that is the one we would swap with the "fixer"

Chuck, I am following along but multiplexing with yard projects-- it's finally spring here in MN so that gives me like two days to get all the outside stuff taken care of before we get 85 degree temps

I got the reset backwards. 0x8C0 starts out with all signals zero on power up, so I guess the scope starts with all ROM and no RAM, save for the 0-2K part down at zero. wrote:

OK, here is where we are at, as far as I can tell. The only scopes we are targeting are the "A" and early "B" models. Every later model has an NVRAM, and the calibration can be restored by simply

Hi Chris, It doesn't matter what they did, we are only using U2260. If you caught an earlier posting I made, I mentioned that you will have to write a single byte to a particular address to force the

I don't think it matters. Our only interest is in writing to the last bytes of the EPROM. Anyone that has a NVRAM in their scope can simply load the EXER 02 constants into the last 256 words of their

OK gang! I changed the Subject to better reflect what we are doing. To test the concept, I took the 256, 16 bit words read from a 2465B using the EXER 02 function, and filled them into a blank Dallas

Chris, In my 2467B, both U2160 and U2260 are populated. Don

Yes- thanks. I won't have time to disassemble my scope for a while so it you can do this experiment, that would be super helpful. I do have preliminary code written but want to study a bit more and

Hi Chris, This is easily tested. Take the 256 values read using the EXER 02 routine, and program them into another NVRAM. Replace the NVRAM in your scope with the EXER 02 NVRAM, and see what happens.

Thank you, Chuck, for the detailed clarification. Don