Does anyone know what type EPROM (memory size and speed) I need to burn HP8350 revision 6 or 7 firmware for U9, U10, U11, and U35. They are DIP 28 pin but I don't know the part number and can't find any other information about them.
Hi, I just open my 8350B, U10, U11 and U35 are AM2764DC and U9 is a D27128.
I just programmed a few minutes ago, version 7.6 with the same EEPROM numbers mentioned above, and everything works fine.
Thank you very much. I have looked through all the service manuals and may have missed it but could not find this information anywhere. I'm new to PROMs and have never tried to burn any myself. I'm going to make an attempt to do so. Do you know if a 28 pin DIP EPROM would work if the memory size is larger? The speed of these looks to be <200ns and I have read that as long as the replacement is equal to or faster that is okay but with memory it says you need the same size. This is something I read about EPROMs in general and not specific to the 8350. Most EPROMs I can find all have more memory typically around 256 to 512. I'm hoping that more memory means I can use that EPROM and have space left over but I'm an analog designer and out of my league with this stuff. Thank you again for opening up your unit and checking that out for me.
Hi, I'm an Analog designer too
Since my 8350B was open, I took the opportunity to do a EEPROM backup and I programmed the version 7.6 and tested unit, everything was OK.
If you use 27256: pin 27 is 5V in 8350B, remove the pin27 from the IC socket, and connect 27256 pin 27 to ground (pin 14).
For 27512: pin 27 and pin 1 are 5V in 8350B, remove the pin27 and pin 1 from the IC socket, and connect 27512 pin 27 and pin 1 to ground (pin 14).
I did test on both (27256 and 27512), everything was OK.
Thank you so much you have been a great help! .
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