just get some W27C512 eeproms, I use them when possible: http://www.ebay.co.uk/itm/10Pcs-2W27c512-45Z- … fsAAOSwubRXEqQs , standard 64kbytes capacity 😀

You can erase the uv eproms with a device like this: http://www.ebay.co.uk/itm/Ultraviolet-Light-U … pAAAMXQydtTOL7F , but why bother? Get the eeproms and call it a day 😉

Thank you - this will definitely be helpful.

I beg to differ. What keropi wrote is true in almost all cases but
once in a blue moon, you might meet a device that simply will *not* take eeproms instead of the UV erasable eprom equvalent***. I am no electrican, I only experienced this along the way... So having a few window-type eprom chips will not hurt either.
(when you cannot find the compatible eeprom, it is all the same)

I have the exact same device keropi mentioned, it only failed when much more power was required (with some DIP32 chips) so I can recommend it.

***I recall one particular Intel NIC that against all docs only recognized an eprom.

Good to know.
So, can one still write with an EPROM burner to a "window" type chip (the one that has to be erased with a UV light)?
Where can I find some of these chips (DIP28 type).

I will probably first try the ones that Keropi suggested.

Yes, very rare are the problems with the higher voltages necessary to program the UV type chips.
I have tried three modernish EPROM burners, two of which are rather cheap Chinese makes but all can do the writing perfectly IF the chip is in good condition.

For buying the chips, I had no better option than ebay.
What is sold is rarely new old stock (but I am not sure whether it is ALWAYS an advantage to be stored over 25 yrs without a single passing-by electron...)
If you buy at ebay, take a good look at the photo, if you judge the label to be original and not laser-razored, repainted and the general shape of the chip is OK, go for it.
For example, I bought some of these and they work flawlessly. These are 16kb only, for network cards.
http://www.ebay.com/itm/5PCS-M27C128A-10F1-IC … 9MAAOSw1x1UMIP7
5PCS M27C128A-10F1

this is for most 486 boards, cheap and widespread, but If you only deal with motherboards, you are lucky because as keropi pointed out almost all can be replaced with an EEPROM which is a better solution.
http://www.ebay.com/itm/5PCS-IC-M27C512-12F1- … hUAAOSw1DtXIsQE

there are even bigger ones, DIP32 etc.
http://www.ebay.com/itm/10pc-ST-M27C801-UV-EP … Slp_lNyB4GBlbSg

you can often find EPROMs at prices better than ebay on chip trading forums such as e.g. http://www.cpu-world.com/forum/

First you need to know what ERPOM you will be replacing.
If it is a 27C512 type then a W27C512 is the eeprom equivalent and just works. W27C512 will work as a replacement for at least 27C128 and 27C256 , these are just 16 and 32kbyte eproms so you fill the remaining space of the W27C512 with the same data (4x 16kbytes or 2x 32kbytes) and it will work just fine.

If you are looking to replace larger eproms like 27C010 or 27C020 then good eeproms equivalents are the 27SF010 and 27SF020.
As a rule ALWAYS compare datasheets and pinouts/rom arrangement to be sure you are getting a suitable eeprom replacement for your eprom.
Some of the smaller eproms might have different pinouts and that could lead to issues...

I haven't faced the issue Jolaes76 describes but in the world of electronincs I find nothing strange nowdays. I can't say the reason since all these old (e)eprom devices are 5v devices when it comes to reading but maybe the NIC didn't like that the larger eeprom was using a couple of pins that are N/C on the smaller eprom... still I can't see why but it can happen apparently 😀

For 386 and 486 mobos though you'll be fine with the W27C512s Jesolo - just keep in mind to fill the whole 64kbytes in case a 386 BIOS is only 32kb and was using originally a 27C256.

Here are some more links from my favorite Chinese seller on eBay when it comes to ICs and related stuff - I see that prices went down on all (e)eproms , that's a good thing!
http://www.ebay.co.uk/itm/10PCS-W27C512-45Z-W … =item51d6ae4c3c
http://www.ebay.co.uk/itm/10PCS-IC-M27C256B-1 … =item46402054e8
http://www.ebay.co.uk/itm/10PCS-IC-M27C512-10 … =item51d6aa4ed4

Thank you Keropi & Jolaes76.
Indeed some very helpful information.

Once I've bought the necessary EPROM burner & EPROM chips, then I might ask for some additional information how to use the software that is bundled with MiniPRO TL866CS.
Based on some Youtube reviews and videos, it would appear that the bundled software already contains a list of the most common IC chips.
So, the way I see it, you just select the IC that you need to "burn" and it will "configure" the settings for you for that particular IC.
I did notice in one video how the reviewer changed the voltages on one of the IC's to 5V (it was set a bit higher), but I'll have a look at this more closely when I get the equipment.

PS: What's the difference between W27C512 & M27C512? The latter appears to have an exposed die, but not the former. I guess they are they both "flashable" EPROM chips? One is just exposed and the other one is not, which means I can also erase the exposed one with a UV light?

Yeah you are correct, you select the correct IC on the programmer software, it auto-configures and then you work with it. For UV eproms the writting voltage will always be bigger than the 5v read one... don't pay attention to these settings, you don't need to mess with them 😉

W27C512 is an eeprom, meaning it's electrically erasable - thus needs no "window" for the UV light to erase it , the programmer does the erasing
M27C512 is a normal UV erasable eprom, you need to expose it to UV light to erase it's contents

Both are writeable once erased, it's the erase procedure that differs. Obviously eeproms are preferred 😉

Yes, I'll probably go for the EEPROM (electrically erasable) one, since I can then easily erase and reprogram the IC, if I stuff up the programming.
I've browsed a bit more on Youtube and the software seems pretty straight forward to use (for someone like me who just wishes to program another BIOS chip).

keropi wrote:

For 386 and 486 mobos though you'll be fine with the W27C512s Jesolo - just keep in mind to fill the whole 64kbytes in case a 386 BIOS is only 32kb and was using originally a 27C256.

I finally managed to obtain a TL866CS burner and tested it briefly. Works fine with the W27C512 EEPROM chips.
Just one question: On the TL866CS, how do I fill the whole 64kbytes if a BIOS is only 32kbytes? Must I tick something on the software that I'm using?

you use dos/command prompt for that:

copy /b 32kb.bin + 32kb.bin 64kb.bin

basically you copy the same 32kb.bin after itself and you get a new file called 64kb.bin

Thank you.
So,you basically just create a file that is 64kb in size and then program it.

Surely that software has an option to start writing from the 32 KB onwards? Like a starting address.

I have the same programmer, I guess you could check the manual for such a feature?

I recently also got one of these cheap china UV EPROM erasers. Can't wait to try it out. I got an old Adaptec SCSI drive that needs a BIOS upgrade 😀

PhilsComputerLab wrote:

Surely that software has an option to start writing from the 32 KB onwards? Like a starting address.
I have the same programmer, I guess you could check the manual for such a feature?

There might be, but I haven't seen anything obvious that will enable me to write out the same data until it fills up the whole 64kb.
There is an option to "write blanks" and also a "starting address", but I wouldn't know what to specify in any event, since my hexadecimal knowledge is fairly limited 🤣.

What keropi explained is quick and easy to do and pretty straight forward.
If I wanted to burn 100 EEPROM chips, then I might say having such an option will be useful, but since I'm only going to use the EEPROM burner once in a while, it's not a big issue for me.

You give up easily 😊

I'll play around with it when I get to it. Hex is just a base 16 number system. Anyway, I'll let you know how I go 😁

Not really. I just like to play in DOS as well 🤣 .
But, let me know if you find anything.

I recently ordered a Genius G540 USB Universal Bios GAL Programmer off ebay - his thing: http://www.ebay.com/itm/321347814855?_trksid= … K%3AMEBIDX%3AIT

Does anyone have any experience with it?

I have that also, it was my first one. In general the Genius is good for newer chips, especially flash. But it cannot do EPROM chips that require higher voltages to write.