Esoteric ROM question - EEPROM in place of EPROM/OTP-PROM?

Blue Jinn

Blue Jinn

Rider of the ARPocalypse
Want to update the firmware on a couple of Kawai synths. 27C512 EPROMs are currently out of stock at the usual places. I may have found some PROMs. Amazon has EEPROMs available. (Assuming they're not counterfeit but it seems a safish bet. ) I'm not that savvy on this kind of thing. The pinouts are all the same, except for these differences:

EPROM EEPROM

14: VSS Ground
22: GVpp OE/Vpp
20: E CE

The E and the G have lines over them. I've only read "REddit" type entries that say they're interchangeable.
 
I would say they are interchaneable.
I've spent a lifetime in electronics, and have seen the size of memory chips grow, and different families introduced.
The pin names may change between families, but they go to some trouble to make their operation compatible.
The sure-fire way to satisfy yourself is to download datasheets for your specific chips. They should be available.
You can then check the voltage levels, and input/output functionality of them.
VSS and Ground are the same thing.
For pin 22, they are both 'Programming Pulse'. One has G, which sounds like ground, and the othe has OE, which sounds like 'Active High Output Enable', but it may be
'Active Low Output Enable' if it is actually '/OE'.
For pin 20, thia looks like E for 'Enable', and CE for 'Chip Enable', which says the same thing.

If there are incompatabilities, you could stand off the chips with turned pin sockets, with that socket pin removed, then strap the chip pin to where it needs to be.
First step is to get the data sheets and study them.
 
Slouching Raymond said:
I would say they are interchaneable.
I've spent a lifetime in electronics, and have seen the size of memory chips grow, and different families introduced.
The pin names may change between families, but they go to some trouble to make their operation compatible.
The sure-fire way to satisfy yourself is to download datasheets for your specific chips. They should be available.
You can then check the voltage levels, and input/output functionality of them.
VSS and Ground are the same thing.
For pin 22, they are both 'Programming Pulse'. One has G, which sounds like ground, and the othe has OE, which sounds like 'Active High Output Enable', but it may be
'Active Low Output Enable' if it is actually '/OE'.
For pin 20, thia looks like E for 'Enable', and CE for 'Chip Enable', which says the same thing.

If there are incompatabilities, you could stand off the chips with turned pin sockets, with that socket pin removed, then strap the chip pin to where it needs to be.
First step is to get the data sheets and study them.
Click to expand...
I have a Yamaha 02R mixing board that needs to be reflashed, is that the right term? I can't find anyone who can do it or how it is done and it just sits here. I have read a bit how to do it? I have had it for probably five years now in this condition. I am getting ready to take it apart and part it out. The meter bridge is probably worth what I
paid for it. I just hate to do it when it is probably such a simple fix.
 
Last edited:
dogooder said:
I have a Yamaha 02R mixing board that needs to be reflashed, is that the right term? I can't find anyone who can do it or how it is done and it just sits here. I have read a bit how to do it? I have had it for probably five years now in this condition. I am getting ready to take it apart and part it out. The meter bridge is probably worth what I
paid for it. I just hate to do it when it is probably such a simple fix.
Click to expand...
I read your thread dogooder.
Re-flashing the chip is full of risks.
The second Kawai stage piano I bought (MP4), was designed with updating the memory via usb in mind, so was designed for it.
My first Kawai stage piano (MP9500), was not designed for easy updating. You coud do it through the midi connector, following a procedure to the letter. But if
anything goes wrong during the procedure, like a power cut, it would mean you're buggered. The keyboard would have to go back to the factory to be fixed.
Consequently I would not even attempt to try to update the MP9500. Leave as is.
I once worked on PC bios software development, and had to install a new bios version to a flash chip on a brand new PC motherboard. The procedure relied on the existing bios to overwrite itself. The trouble was, the new bios version had bugs, and didn't work properly. The knock-on result of this was the bios updating procedure in the bios could not work either.
The motherboard was now dead as a dodo, and would have to return to the factory for fixing.

In your case, dogooder, why would corrupted CMOS ram data effect the contents of a flash memory chip?
I would assume the chip data is still good, and look elsewhere for a fault.
If you could re-flash the chip, you could actually be splatting good data.
Consider how the mixer sets up data in the CMOS ram in the first place. It is likely to have an initializing routine embedded to fill the ram with default data.
It may be invoked by a jumper being fitted or not, during power-up.
Perhaps the manual, or support FAQs, may say something about this.
Questioning dodgy cables or cheap sockets, is a good stratergy.

All in all, don't rush into re-flashing.
 
Blue Jinn said:
Yes. I checked and I think it's a pretty common programmer:
Click to expand...
I chucked out my expensive perfectly good Eprom programmer some years ago. It only ran on a DOS parallel port. Eproms were yesterday's technology.
I doubt whether Eproms are even made today. Everything is Flash now.
 
Slouching Raymond said:
I read your thread dogooder.
Re-flashing the chip is full of risks.
The second Kawai stage piano I bought (MP4), was designed with updating the memory via usb in mind, so was designed for it.
My first Kawai stage piano (MP9500), was not designed for easy updating. You coud do it through the midi connector, following a procedure to the letter. But if
anything goes wrong during the procedure, like a power cut, it would mean you're buggered. The keyboard would have to go back to the factory to be fixed.
Consequently I would not even attempt to try to update the MP9500. Leave as is.
I once worked on PC bios software development, and had to install a new bios version to a flash chip on a brand new PC motherboard. The procedure relied on the existing bios to overwrite itself. The trouble was, the new bios version had bugs, and didn't work properly. The knock-on result of this was the bios updating procedure in the bios could not work either.
The motherboard was now dead as a dodo, and would have to return to the factory for fixing.

In your case, dogooder, why would corrupted CMOS ram data effect the contents of a flash memory chip?
I would assume the chip data is still good, and look elsewhere for a fault.
If you could re-flash the chip, you could actually be splatting good data.
Consider how the mixer sets up data in the CMOS ram in the first place. It is likely to have an initializing routine embedded to fill the ram with default data.
It may be invoked by a jumper being fitted or not, during power-up.
Perhaps the manual, or support FAQs, may say something about this.
Questioning dodgy cables or cheap sockets, is a good stratergy.

All in all, don't rush into re-flashing.
Click to expand...
I have tried the initializing procedure outlined in the manual to reset the factory settings and no go.
 
alt=

reflashable 27C512's
 
Last edited:
dogooder said:
I have tried the initializing procedure outlined in the manual to reset the factory settings and no go.
Click to expand...
I used to have one of those DATA I/O boxes. I bought at an electronics "garage sale" and then sold it to the same guy I bought one of the interchangeable socket attachments from. I used it to program a small prom on an XT motherboard so it could access 1MB of RAM. The XT boards had that chip socketed and emply sockets for additional RAM. It was a fun (yeah, nerd alert) exercise. Found the code online for the chip. After you instlaled that, you could load device drivers, like the mouse "high" and free up more RAM below 640k.
 
Slouching Raymond said:
I chucked out my expensive perfectly good Eprom programmer some years ago. It only ran on a DOS parallel port. Eproms were yesterday's technology.
I doubt whether Eproms are even made today. Everything is Flash now.
Click to expand...
Somewhere, I think I still have an EPROM burner that connected to the serial port of an Atari computer. Software is long gone, so it's worthless. There's also a box with a few EPROMs that are erased with UV light. I think they are vintage 1990s. I traded a Jordan Boss Tone fuzz for the burner. Turns out that I got the short end of the stick. The Jordan is probably worth about $100 or so.
 
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