The MX27C1000-15 is not an EEPROM (EE stands for electrically erasable), it must be erased using UV light before being programmed (unless it is still blank) .

See

I've found a datasheet similar where it talks about MX27C1000 1M-BIT CMOS EPROM and talks about fast programming mode when applied 12,5v to VPP, there's no trasparent hole for UV light on the package. On the package there's "MX 27C10000pC-15 M24921 VPP = 12,5v".
I don't understand the point of having that VPP pin.. 🙁

Some more info found here LuckyStar LS486E - only 12V Bios Flash Voltage?

386SX wrote on 2020-05-31, 18:53:

I've found a datasheet similar where it talks about MX27C1000 1M-BIT CMOS EPROM and talks about fast programming mode when applied 12,5v to VPP, there's no trasparent hole for UV light on the package. On the package there's "MX 27C10000pC-15 M24921 VPP = 12,5v".
I don't understand the point of having that VPP pin.. 🙁

It's for the initial programming . If it has no window, it's OTP (one-time programmable) .

darry wrote on 2020-05-31, 18:57:

386SX wrote on 2020-05-31, 18:53:

I've found a datasheet similar where it talks about MX27C1000 1M-BIT CMOS EPROM and talks about fast programming mode when applied 12,5v to VPP, there's no trasparent hole for UV light on the package. On the package there's "MX 27C10000pC-15 M24921 VPP = 12,5v".
I don't understand the point of having that VPP pin.. 🙁

It's for the initial programming . If it has no window, it's OTP (one-time programmable) .

So there's no way to program it? What if I use another type of 32 pin eprom into it? The LS486e board I have has the 27C010/512 marking on the pcb, may it work with another programmable eeprom?

386SX wrote on 2020-05-31, 18:59:

darry wrote on 2020-05-31, 18:57:

386SX wrote on 2020-05-31, 18:53:

I've found a datasheet similar where it talks about MX27C1000 1M-BIT CMOS EPROM and talks about fast programming mode when applied 12,5v to VPP, there's no trasparent hole for UV light on the package. On the package there's "MX 27C10000pC-15 M24921 VPP = 12,5v".
I don't understand the point of having that VPP pin.. 🙁

It's for the initial programming . If it has no window, it's OTP (one-time programmable) .

So there's no way to program it? What if I use another type of 32 pin eprom into it? The LS486e board I have has the 27C010/512 marking on the pcb, may it work with another programmable eeprom?

It would have to be pin compatible, same capacity or bigger and, if using a UV erasable one, you would of course need to erase it first using a UV light source .

EDIT: Oh, and whatever flashing software would need to support programming that specific model .

darry wrote on 2020-05-31, 19:12:

386SX wrote on 2020-05-31, 18:59:

darry wrote on 2020-05-31, 18:57:

It's for the initial programming . If it has no window, it's OTP (one-time programmable) .

So there's no way to program it? What if I use another type of 32 pin eprom into it? The LS486e board I have has the 27C010/512 marking on the pcb, may it work with another programmable eeprom?

It would have to be pin compatible, same capacity or bigger and, if using a UV erasable one, you would of course need to erase it first using a UV light source .

But still, how it would be programmed? After the erasing I'd have only one time programming attempt using the way I was trying to?

386SX wrote on 2020-05-31, 19:15:

darry wrote on 2020-05-31, 19:12:

386SX wrote on 2020-05-31, 18:59:

So there's no way to program it? What if I use another type of 32 pin eprom into it? The LS486e board I have has the 27C010/512 marking on the pcb, may it work with another programmable eeprom?

It would have to be pin compatible, same capacity or bigger and, if using a UV erasable one, you would of course need to erase it first using a UV light source .

But still, how it would be programmed? After the erasing I'd have only one time programming attempt using the way I was trying to?

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the scenario of flashing such a chip in a motherboard would never occur (except when hot-flashing, which no manufacturer would support anyway) .

Other than using an external programmer, you may be able to hotflash using something like uniflash under DOS or flashrom under Linux, but I do not know if either supports programming UV erasable chips .

EDIT: I see you already tried uniflash .

darry wrote on 2020-05-31, 19:23:

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the sc […]
Show full quote

386SX wrote on 2020-05-31, 19:15:

darry wrote on 2020-05-31, 19:12:

It would have to be pin compatible, same capacity or bigger and, if using a UV erasable one, you would of course need to erase it first using a UV light source .

But still, how it would be programmed? After the erasing I'd have only one time programming attempt using the way I was trying to?

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the scenario of flashing such a chip in a motherboard would never occur (except when hot-flashing, which no manufacturer would support anyway) .

Other than using an external programmer, you may be able to hotflash using something like uniflash under DOS or flashrom under Linux, but I do not know if either supports programming UV erasable chips .

EDIT: I see you already tried uniflash .

I may try forcing some other flash code with Uniflash but I'm not sure of an equivalent one. For example I suppose The 29C010A various brand should be 128k x 8 but looking at the pinout the pin 31 is called WE but in the 27c1000 is called PGM, the others seems equal beside the pin 1 that is NC instead of VPP (12v).
Also I was thinking buy a classic 29C010A-15PC to try flashing the 128kbyte rom into it. What do you think?

386SX wrote on 2020-05-31, 21:00:

darry wrote on 2020-05-31, 19:23:

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the sc […]
Show full quote

386SX wrote on 2020-05-31, 19:15:

But still, how it would be programmed? After the erasing I'd have only one time programming attempt using the way I was trying to?

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the scenario of flashing such a chip in a motherboard would never occur (except when hot-flashing, which no manufacturer would support anyway) .

Other than using an external programmer, you may be able to hotflash using something like uniflash under DOS or flashrom under Linux, but I do not know if either supports programming UV erasable chips .

EDIT: I see you already tried uniflash .

I may try forcing some other flash code with Uniflash but I'm not sure of an equivalent one. For example I suppose The 29C010A various brand should be 128k x 8 but looking at the pinout the pin 31 is called WE but in the 27c1000 is called PGM, the others seems equal beside the pin 1 that is NC instead of VPP (12v).
Also I was thinking buy a classic 29C010A-15PC to try flashing the 128kbyte rom into it. What do you think?

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I do not know if randomly trying to force writing using code meant for another model would risk damaging the chip, but I would not try it .

Personally, I just ordered a TL866II Plus to handle my flashing needs .

As for the UV erasing part, you can still buy erasing lamps .

darry wrote on 2020-05-31, 21:08:

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I […]
Show full quote

386SX wrote on 2020-05-31, 21:00:

darry wrote on 2020-05-31, 19:23:

It is quite likely that awdflash does not support UV erasable EPROMs of any kind . You can't boot from an empty EPROM, so the scenario of flashing such a chip in a motherboard would never occur (except when hot-flashing, which no manufacturer would support anyway) .

Other than using an external programmer, you may be able to hotflash using something like uniflash under DOS or flashrom under Linux, but I do not know if either supports programming UV erasable chips .

EDIT: I see you already tried uniflash .

I may try forcing some other flash code with Uniflash but I'm not sure of an equivalent one. For example I suppose The 29C010A various brand should be 128k x 8 but looking at the pinout the pin 31 is called WE but in the 27c1000 is called PGM, the others seems equal beside the pin 1 that is NC instead of VPP (12v).
Also I was thinking buy a classic 29C010A-15PC to try flashing the 128kbyte rom into it. What do you think?

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I do not know if randomly trying to force writing using code meant for another model would risk damaging the chip, but I would not try it .

Personally, I just ordered a TL866II Plus to handle my flashing needs .

As for the UV erasing part, you can still buy erasing lamps .

Sorry if I don't understand but why should I need an UV erasing one even in the case of an equivalent real eeprom, like I just did on the Socket 7 mainboard 29C010A and then put that eeprom into the 486 mobo to replace the 27c1000 unflashable one? Most of these chips have no UV glass onto them and still programmable with Uniflash (not the 27c1000 but an equivalent uniflash compatible one).

386SX wrote on 2020-05-31, 21:29:

darry wrote on 2020-05-31, 21:08:

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I […]
Show full quote

386SX wrote on 2020-05-31, 21:00:

I may try forcing some other flash code with Uniflash but I'm not sure of an equivalent one. For example I suppose The 29C010A various brand should be 128k x 8 but looking at the pinout the pin 31 is called WE but in the 27c1000 is called PGM, the others seems equal beside the pin 1 that is NC instead of VPP (12v).
Also I was thinking buy a classic 29C010A-15PC to try flashing the 128kbyte rom into it. What do you think?

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I do not know if randomly trying to force writing using code meant for another model would risk damaging the chip, but I would not try it .

Personally, I just ordered a TL866II Plus to handle my flashing needs .

As for the UV erasing part, you can still buy erasing lamps .

Sorry if I don't understand but why should I need an UV erasing one even in the case of an equivalent real eeprom, like I just did on the Socket 7 mainboard 29C010A and then put that eeprom into the 486 mobo to replace the 27c1000 unflashable one? Most of these chips have no UV glass onto them and still programmable with Uniflash (not the 27c1000 but an equivalent uniflash compatible one).

Sorry, I misread 29C010A-15 as 27C010A-15 . No, you won't need a UV eraser for that .
My bad . If it is pin and voltage compatible, it should work fine .

darry wrote on 2020-05-31, 21:55:

386SX wrote on 2020-05-31, 21:29:

darry wrote on 2020-05-31, 21:08:

You will still need to UV erase the EPROM before writing (unless you buy a used pre-blanked one or actually find a new one) . I do not know if randomly trying to force writing using code meant for another model would risk damaging the chip, but I would not try it .

Personally, I just ordered a TL866II Plus to handle my flashing needs .

As for the UV erasing part, you can still buy erasing lamps .

Sorry if I don't understand but why should I need an UV erasing one even in the case of an equivalent real eeprom, like I just did on the Socket 7 mainboard 29C010A and then put that eeprom into the 486 mobo to replace the 27c1000 unflashable one? Most of these chips have no UV glass onto them and still programmable with Uniflash (not the 27c1000 but an equivalent uniflash compatible one).

Sorry, I misread 29C010A-15 as 27C010A-15 . No, you won't need a UV eraser for that .
My bad . If it is pin and voltage compatible, it should work fine .

No problem. 😀
Strange thing happened. Using Uniflash I force the 27C1000-15 to (try to) "flash" it with the code of the 29F1000 with the 12v applied to the pin 1 VPP and the program worked successfully at least it said that but once put that into the 486 mobo it doesn't boot just like before with the C7 register test post pci code. I can't understand if it actually did try to flash it or didn't even get it for the reasons discussed above.
Anyway, I'll buy some similar flashable eeproms to try. That specific WinBios C7 code happened as well before so I always thought it would be a bios problem (even if strange thing with an AMD DX4-100 it stops at "00" code but I suspect some cpu I have may be broken too.

I was thinking about one thing, the 5V or 12V jumper selection on the mobo what pin does the voltage change? Because in the manual under the 12 volt mode it says Intel / MX and that MX seems to sound like the Macronix the 27C1000 is. So I'd expect it to give a 12 volt to the first pin VPP right (and not the VCC 31 pin that I imagine would burn any 5v eeprom).

I'm pretty sure the they are referring to VPP when they say 5v vs 12v, for chips like the MX28F1000P that requires 12V on VPP for programming but whose VCC is 5v .

darry wrote on 2020-06-01, 10:06:

I'm pretty sure the they are referring to VPP when they say 5v vs 12v, for chips like the MX28F1000P that requires 12V on VPP for programming but whose VCC is 5v .

I may try again without using the external 12v but using the internal one even if I've to change voltage jumpers while system is on and the original bios is detached, because the original bios is 5V one and I don't know what could happen in a 5v only not-VPP enabled bios when the jumper is on 12V.