You need to check what programming voltage (5V or 12V) the chip uses and jumper the motherboard you are going to use for that programming voltage should it be different from what the boards own flash chip uses.

Other than that if the chip fits the socket and Uniflash recognises the chip it should work.

Ok... got something

found out the board needs a 1mbit eeprom.
found out the 32pins 27c1024 chip i had for it was 12v (edit: maybe not)
found a pentium 430tx board with 32pins 1mbit chip 5v
found another 32pins 1mbit chip 5v

Booted the tx board from floppy, took out the bios chip, inserted other 1mbit chip and with uniflash i flashed it with 486 bios. It said succesfull!

Inserted it in the 486 board and it did nothing..... 😵 😢 (i did configure it for dx4 amd)

After multiple ram sticks, videocards etc. i failed to start it up. I inserted the 27c1024 chip i initially had choosen for it (from a box of bios chips from the same place i got the board).
I choose this one because it said 27c1024 and on the board it said 271024 by the socket. I didn't want to take the risk before. It was a bucket with 100-200 bios chips!

IT CAME TO LIFE!!!! Was i THAT lucky??

Unfortunately it says bios checksum error and NO KEYBOARD present. 😐
It DOES look for a floppy drive and boot from it but without a keyboard i can do nothing.

What can i do to get my keyboard working? I tried a few other keyboards but that didn't help. Did even try a usb pci card and a usb keyboard but ofcourse that doesn't work either.
There is a flashprogram for this board so all i need is a working keyboard to flash it.

Details:

It only boots with ram inserted in slot2, only ram in slot1 does nothing, same as 3 and 4 (can't see a memory count with no bios ofcourse).
It does only boot with a keyboard attached, otherwise it doesn't display anything.
I did find 2 pins shorting on the chipset. I separated them but i found it AFTER the first powerup so i might have some damage?

Please help 🤣

Interesting... All the 27C1024 chips I saw had 40 pins. What's the make of yours?

yeah, something is off. I've read that too and also that a 27 series should be an eprom instead of an eeprom but mine does not have the uv window...

There is a sticker on top that says award software 1995 blahblah and underneath the sticker there is a white text only saying ''27c1024'' no brand, nothing.

On the pin side it says taiwan and a bunch of numbers that even google knows nothing about.

I will try and flash this thing on the tx board and see how it goes.....fingers crossed. 😈

It's also odd that GA 486AM would have 271024 printed on its PCB because I only saw them having 32pin sockets.
Before your attempt to flash the 27C1024 chip, it's better to dump its content first... Well you might have already dumped it 😎

hahaha ofcourse not! I dumped nothing, just flashed it and now it doesn't do anything anymore 😎

Very weird, maybe it is the right chip but then the bios was damaged anyway. But if i flash it with uniflash and it says succesfull why doesn't it work? Flashing does go too quick it seems, as normally flashing a bios takes a whole lot longer.

But it is only 128k and it says ''succesfull''.

More ways to flash such a chip?

So you flashed a supposed-to-be 12V chip on a 5V board? It's getting odder and odder.... Can you flash it with the TX BIOS and see if the chip and flasher work as expected to?

EDIT:

Uniflash should be able to identify the make and model of the flash chip, right? What does it say?

lazibayer wrote:

So you flashed a supposed-to-be 12V chip on a 5V board? It's getting odder and odder.... Can you flash it with the TX BIOS and see if the chip and flasher work as expected to?

EDIT:

Uniflash should be able to identify the make and model of the flash chip, right? What does it say?

Yes, i did.... nothing blew up 😎

I will see what uniflash says, i'll be back. I'm so glad that i normally can simply do a hotflash with the same board because i mostly pick boards that i have but want backups for.
This is frustrating stuff.. 🤣

ok, uniflash did not detect the ''27c10124'' but it did say ''succesful'' after flashing it...... afterwards it didn't even show the bootblock error anymore on the 486 so it did flash something, or messed it up.

uniflash did read the original tx chip (winbond 1mbit 5v), i backed it up and put in a SST 1mbit 5v chip which uniflash read fine and after flashing the tx bios it booted as well.

So, that 1mbit 5v chip can be flashed and read. Flashed it with the ga-486am/s file and inserted it into the 486 board. Nothing, not a beep. Even downloaded the bios file from another source just to be sure.

So, conclusion: The 1mbit chip that should be on the gigabyte 486 needs to be another type of chip? Does it need a 12v chip and if yes, on what board can i flash that? (i have plenty of options when it comes to boards, but all pentium1 and up).

Can anyone read the chip on their ga-486am/s and please let me know what type of eprom or eeprom chip it is?

Thanx!

btw, i'm out of options when it comes to 1mbit eeproms, all i have left is a bunch of 2mb, can i use that?

meljor wrote:

ok, uniflash did not detect the ''27c10124'' but it did say ''succesful'' after flashing it...... afterwards it didn't even show […]
Show full quote

ok, uniflash did not detect the ''27c10124'' but it did say ''succesful'' after flashing it...... afterwards it didn't even show the bootblock error anymore on the 486 so it did flash something, or messed it up.

uniflash did read the original tx chip (winbond 1mbit 5v), i backed it up and put in a SST 1mbit 5v chip which uniflash read fine and after flashing the tx bios it booted as well.

So, that 1mbit 5v chip can be flashed and read. Flashed it with the ga-486am/s file and inserted it into the 486 board. Nothing, not a beep. Even downloaded the bios file from another source just to be sure.

So, conclusion: The 1mbit chip that should be on the gigabyte 486 needs to be another type of chip? Does it need a 12v chip and if yes, on what board can i flash that? (i have plenty of options when it comes to boards, but all pentium1 and up).

Can anyone read the chip on their ga-486am/s and please let me know what type of eprom or eeprom chip it is?

Thanx!

btw, i'm out of options when it comes to 1mbit eeproms, all i have left is a bunch of 2mb, can i use that?

Socket 3 and Socket 7 boards often have a jumper to change between 12V and 5V flash programming voltage.

I use (or more like "used to use" as I have no idea where it is at the moment) a i430 VX board of some kind to flash both types.

meljor wrote:

Yes, i did.... nothing blew up 😎

Actually I didn't quite get it... I guess you flashed the mysterious 27C1024 chip with 430TX BIOS and it couldn't boot the 430TX board?

meljor wrote:

ok, uniflash did not detect the ''27c10124'' but it did say ''succesful'' after flashing it...... afterwards it didn't even show the bootblock error anymore on the 486 so it did flash something, or messed it up.

Mmmm the uniflash I have (version 1.4) won't let me flash if the chip type is not detected or forced.

meljor wrote:

So, conclusion: The 1mbit chip that should be on the gigabyte 486 needs to be another type of chip? Does it need a 12v chip and if yes, on what board can i flash that? (i have plenty of options when it comes to boards, but all pentium1 and up).

Usually a 12V chip means it requires 12V to flash but only 5V for normal reading operations. A 5V chip can work just fine in a 12V socket as long as they are pin-compatible and no flashing is carried out. Your 5V chip will be fried at boot if the board supplies 12V for normal operations.

meljor wrote:

btw, i'm out of options when it comes to 1mbit eeproms, all i have left is a bunch of 2mb, can i use that?

It could; but first we need to figure out the chips that GA-486AM/s use so we can estimate possible substitutes.

Yes, i did flash the 27c1024 chip on the 430tx. Uniflash could not detect it but said flash ''succesfull'' anyway. And yes you are right, it did not work on the 486 and now it doesn't even do the bootblock/checksum/keyboard error anymore.

So, the bios file is 128kb, that means a 1mbit eeprom is needed right? So i flashed one that was detected by uniflash and also ''succesfull'' but it still will not work on the 486.
When i flash the 430tx bios on it it works fine, so the chip works.

Is it possible that the 486 needs a completely different chip? Is it possible it NEEDS a 271024 chip and cannot read others?

If someone can see on his gigabyte board which chip it uses i can possibly do the flash succesfully. It can also be that the board is dead but it DID show a bootblock checksum error before.

I have searched for images but they all have the damn sticker on the bios chip 🤣

meljor wrote:

I have searched for images but they all have the damn sticker on the bios chip 🤣

Same here 🤣
Another dumb question: have you cleared the CMOS after putting the flashed 27C1024 on the 486 board?

Good question. Normally i would but i have no idea how to that on this board. I've searched the manual also, but nothing came up...

These 486 things are weird. I have a vlb one, took me a while to get that fast, nice and stable. Then i finally found a pci board but it goes all crazy on me as soon as i try to run an amd 133 at the 4x multi. It needs a bios update but i didn't want to mess with it as it runs fine with a 3x multi.

Now i have this one. Should be one of the best if i get it running....

Hopefully i can at least find out what kind of chip it originally has.

I downloaded the flasher that Gigabyte provided for this board. It supports the following chips:

SST 28EE010 & 28EE011 /5V
AMD 29F010 /5V
INTEL 28F001BX-T /12V 28F010 /12V
WINBOND 29EE011 /5V
MXIC 28F1000AP /12V
MXIC 28F1000P /12V
ATMEL 29C010A /5V
ATMEL 29C010A /3V
CSI CAT28F001P /12V

I checked a few of them but couldn't find the odd balls here. Some of them use PIN1 as VPP and PIN30 as power-down but these two pins are usually NC on 1M chips. To be absolutely safe you can simply bend these two pins so they don't contact with the socket.

Google image tells me this board uses DS12887 as real time clock. According to the datasheet you can clear CMOS by grounding PIN21.

SST PH29EE01 is the chip i used, looks to me like the same as the winbond?

I will check every single jumper again and reset the bios in the next days. Have to sleep now and work tomorrow.
I will report back if i find anything (or when i gave up).

Really appreciate the help so far!

Hey.....psssssst!

GUESS WHO'S RUNNING SPEEDSYS RIGHT NOW!!!!! The little f*ck works!

I made it a bit more crazy today and just started putting in RANDOM (2mbit) bios chips! I came to this because the ''27c1024'' chip had a sticker that said award bios 1995 586 etc..
I thought about that and started searching google and every 486 i found had award sticker with ''486'' on it.

So, it could never have been the correct chip for this board but it DID give me the bootblock and a sign of life right?.
After searching Google about award bootblock it basicly said that even if the bios is completely messed up, bootblock might still make the pc work.

Then i thought, what the hell, try other award chips and see what it gives me.....

I put in the next oldest i had and it said award 586 1997. It gave a bootblock error! This time no keyboard error so i was in business!
Then it made funny noises from my floppy drive and gave i/o errors.... 😢 😵

Shut off, checked every cable etc. grabbed another floppy disk and......no boot. Nothing. 10 tries, nothing.

Cursed a couple of times, relaxed again, saying things to myself like ''it's supposed to be a hobby'' and put in another chip: award 686 1998. Nothing.

Put back the previous one: Bootblock again! No i/o error and no keyboard error and made it all the way into uniflash! But....it was a 2mbit chip (uniflash gave ''unknown'') so no way this could be flashed with the 1mbit bios file... Popped out the chip and the system hang.....damn.
Rebooted 10 times, nothing! Frustrating!!!

Popped out the Dallas RTC (it is socketed!) and the eeprom. Put the dallas back in and grabbed the 1mbit eeprom i flashed yesterday on the 430TX (don't know why i did that now) and it booted and said dx4 100mhz blah blah and i was like WHAT???? It worked!!!

All i can think of is: You were right and it simply needed a ''cmos clear'' and popping out the RTC did that. I can not think of anything else.

Thanx for all the help anyway!

Learned a lot along the way 😎 😎 😎

Big congrats!
I think clear cmos is the most likely cure 🤣

Thank you!

Could very well be. Or maybe it was a loose connection: Sometimes it gives no display now and after i wiggle the vga card and ram sticks it works again (test setup so everything is loose). Ones it is running it keeps working.
Will clean everything and i think that will do the trick. Some of these parts at the scrapper were laying outside the building for a while so could be dirt/corrosion of some sort.

Most important now for me is the fact that i learned something about award bootblocker and how it could be used to ''save'' some corrupt bioses and also that for a succesfull hotflash i don't need an identical board. Also learned something about the size of bios chips and the different versions. Nice!

The reason i wanted a better pci board is the fact that my Acer ap43 has an old bios version and i cannot get my amd 5x86 133mhz cpu working with it as it should. As soon as i select the 2x multi (=4x) it starts acting weird and disables cache etc. It is now running at 3 x 50fsb but the busspeed is too high and it needs very loose timings. My goal was 4 x 40fsb for a nice and fast 160mhz 486 pci.
Other people got it working but have a newer bios so i know that is the problem.

Now i have the gigabyte board with latest bios and it should work fine!

But before all this i was scared to touch the bios of the Acer....but looking at it, it also has a dip32 socket so now i think i will hotflash this one too!
I will keep the original chip and simply flash another one so there is minimal risk.

One problem: i can't find a bios file for it! HELP? 🤣