EPROM 27C800 for A1200 - Backup & Restore !?

[freesofia]

Good! I have the following case study!

I have 2x2 absolutely identical EPROM 27C800 Amiga Kickstart ROM's 3.2.1 (47.102) purchased from amigastore.eu, for two A1200s that I have! (I just peeled off the stickers on the bottom two)
One A1200 broke down and I decided to do an experiment with the two 27C800 units that were used on it!
I erased them perfectly with a UVC lamp (Blank check = OK) !
With Xgecu TL866 II Plus and this adapter: https://github.com/mafe72/27c160-tl866-adapter - I backup the two working Lo & Hi chips, bank 0 and bank 1 according to the instructions in the link and try to I wrote to the already deleted identical two chips again in the same way as writing twice.
Everything goes perfectly plus Verify - but after I put the (already saved chips on my working Amiga 1200) it goes to a black screen!

Can anyone tell me what I'm missing?

[btp]

I would suggest to use the .bin files provided in AmigaOS 3.2.x
To fill the 27C800 (which is 1MB EPROM) you must concatenate .bin files using the following command in a DOS prompt:
copy /B A1200.47.111-hi.bin + A1200.47.111-hi.bin A1200.47.111-hi-1MB.bin

Then use the XGPro software of your programmer to burn the A1200.47.111-hi-1MB.bin file (should be exactly 1048576 bytes)

Do the same process for the A1200.47.111-lo.bin ROM and you should be good to go.

[freesofia]

Originally Posted by btp

I would suggest to use the .bin files provided in AmigaOS 3.2.x
To fill the 27C800 (which is 1MB EPROM) you must concatenate .bin files using the following command in a DOS prompt:
copy /B A1200.47.111-hi.bin + A1200.47.111-hi.bin A1200.47.111-hi-1MB.bin

Then use the XGPro software of your programmer to burn the A1200.47.111-hi-1MB.bin file (should be exactly 1048576 bytes)

Do the same process for the A1200.47.111-lo.bin ROM and you should be good to go.

Thank you for the clarification, but apparently it still didn't work!?
I'm on a black screen again!

[supaduper]

I take it you put the roms in the right sockets, I.E LO = U6B and Hi = U6A, just asking as it is easy mistake to make

[freesofia]

Originally Posted by supaduper

I take it you put the roms in the right sockets, I.E LO = U6B and Hi = U6A, just asking as it is easy mistake to make

Absolutely!
Lo - always in U6B
Hi - always in U6A
I even did an experiment and compared the broken, just working 2 pieces of 47.102 and "concatenate" and recorded 47.102 - there is no difference between them!
I'm already thinking that I'm not doing something right!?

[supaduper]

Using the 27c800 eprom, so you write say the LO file 512k to Bank 0 then LO file 512k to again Bank 1 ? this will give you a 1mb LO rom, you do exactly the same to get the HI 1mb rom

When copying the orignal 3.2.1.roms ( if they are 27c800 1mb roms) you only need to copy Bank 0 as it will be 512k then you write this twice to your empty rom Bank 0 Bank 1
You do not have to concatenate them they are already 512k, only need to concatenate to 1mb if you are going to write the whole 1mb file in one hit

thats how you use the adapter you have

[freesofia]

Originally Posted by supaduper

Using the 27c800 eprom, so you write say the LO file 512k to Bank 0 then LO file 512k to again Bank 1 ? this will give you a 1mb LO rom, you do exactly the same to get the HI 1mb rom

When copying the orignal 3.2.1.roms ( if they are 27c800 1mb roms) you only need to copy Bank 0 as it will be 512k then you write this twice to your empty rom Bank 0 Bank 1
You do not have to concatenate them they are already 512k, only need to concatenate to 1mb if you are going to write the whole 1mb file in one hit

thats how you use the adapter you have

I did this at least 10 times before I read the opinion of: @btp https://eab.abime.net/member.php?u=61565

P.S:
Interestingly, when I peeled off the stickers the first time to erase the chips and write them with the bkup of the other two, I saw that they were different versions of the 27C800 ?!
I am attaching a photo!

[supaduper]

They should be ok, but as you know there are lots of reprinted EPROMS out there, so you still have not managed to write the roms ?, if not not then one of them could be faulty

[freesofia]

Originally Posted by supaduper

They should be ok, but as you know there are lots of reprinted EPROMS out there, so you still have not managed to write the roms ?, if not not then one of them could be faulty

I understand.
But until 2 days ago these roms were working before I deleted them for the test!
They were branded by amigastore as I bought them...
In a little while I will upload a video on youtube of the whole recording procedure... maybe someone can see something that no one else can see, and I'm doing it wrong... does anyone know!?

[ Show youtube player ]

[Exodous]

I'm not familiar with that programmer/software, where you seem to have to flip the DIP switch to access the upper/lower range of the EPROMs, but rather than verifying what was just written with the programmer, I would suggest you take a step back.

For each EPROM and upper/lower range within that EPROM:
o Clear the buffer
o Read the contents of the EPROM
o Save it to disk

When you have all the contents from both the untouched EPROMs and the ones you've re-programmed, use a comparison tool on Windows which can compare in hex (If you don't have one, take a look at BeyondCompare) to confirm that what has been read matches for the respective hi/lo and upper/lower ranges. If it doesn't, then it may be either a few faulty bits in the EPROM, or something more extreme like the data has been byte swapped before being written.

If the files match, then if you concatenate the upper/lower files for each EEPROM, it should also match the original binary files you've written.

If there are differences, I would suggest you write each individual file taken from the untouched EPROMs to the respective part on the others and see if that works.

[supaduper]

Looking at your Video when you program the eprom you leave the switch at Bank 1 then do Bank 0, I have always done it the other way round Bank 0 then Bank 1, When I copy a rom I also do Bank 0 then Bank 1, and I never change the 100us to 50us in the software settings either, never had a problem
I have some 3.2 roms I will do as you do and see if I get the same result

[freesofia]

Originally Posted by supaduper

Looking at your Video when you program the eprom you leave the switch at Bank 1 then do Bank 0, I have always done it the other way round Bank 0 then Bank 1, When I copy a rom I also do Bank 0 then Bank 1, and I never change the 100us to 50us in the software settings either, never had a problem
I have some 3.2 roms I will do as you do and see if I get the same result

Let's see if I understood you correctly?!
When programming the rom should I do it with bank 1 first and then bank 0?
I do it as described in the documentation of the board from the link: https://github.com/mafe72/27c160-tl866-adapter
Therefore:
bank 0 and then bank 1
Does that mean the documentation is wrong?!

[freesofia]

Originally Posted by Exodous

I'm not familiar with that programmer/software, where you seem to have to flip the DIP switch to access the upper/lower range of the EPROMs, but rather than verifying what was just written with the programmer, I would suggest you take a step back.

For each EPROM and upper/lower range within that EPROM:
o Clear the buffer
o Read the contents of the EPROM
o Save it to disk

When you have all the contents from both the untouched EPROMs and the ones you've re-programmed, use a comparison tool on Windows which can compare in hex (If you don't have one, take a look at BeyondCompare) to confirm that what has been read matches for the respective hi/lo and upper/lower ranges. If it doesn't, then it may be either a few faulty bits in the EPROM, or something more extreme like the data has been byte swapped before being written.

If the files match, then if you concatenate the upper/lower files for each EEPROM, it should also match the original binary files you've written.

If there are differences, I would suggest you write each individual file taken from the untouched EPROMs to the respective part on the others and see if that works.

I compared them exactly as you explained and they are absolutely identical!

[alexh]

If the EPROM chips contents are correct. They are inserted correctly. They worked previously.

Have you accidentally broken the A1200 ROM socket(s)?

[supaduper]

Just tested reading and writing 3.2.2. roms as you did and had no problem writing them exactly as you show in the Video so cannot see why you cannot do the same
Also I now think it does not matter which way round Bank 0 then bank 1 as I did it your way Bank 1 then Bank 0 and it still worked

Have you ever burned any other ROMs with this programmer ? perhaps it is faulty

[freesofia]

Originally Posted by alexh

If the EPROM chips contents are correct. They are inserted correctly. They worked previously.

Have you accidentally broken the A1200 ROM socket(s)?

I do not understand! The ROM socket is not broken.
Or at least I don't see it being damaged anywhere.
Working chips work on this board without any problems!

[freesofia]

Originally Posted by supaduper

Just tested reading and writing 3.2.2. roms as you did and had no problem writing them exactly as you show in the Video so cannot see why you cannot do the same
Also I now think it does not matter which way round Bank 0 then bank 1 as I did it your way Bank 1 then Bank 0 and it still worked

Have you ever burned any other ROMs with this programmer ? perhaps it is faulty

I only have this programmer and no other to test with!

[supaduper]

Originally Posted by freesofia

I only have this programmer and no other to test with!

also what I did was just burn the LO rom and tested it with the original HI rom, so you can do that to so that it will test the Eproms to see if one is bad

[alexh]

Take 2:

• The chips used to work with different contents written by someone else.
• The ROM sockets work with different ROMs written by someone else.
• The ROMs you wrote read back the same contents as you programmed them with...
• The ROMs you wrote don't work in A1200

This can only mean the EPROM programmer must be reading/writing the data in the wrong order. i.e. driving the address pins incorrectly. This can happen if it has detected the wrong EPROM type/model OR the adapter is wrong.

Instead of using a file, read the ROMs that work and write this data to the other EPROMs. It should read back wrong but also write it wrong which should make it correct if you see what I mean?

[freesofia]

Thanks everyone for the discussion and guidance!
Now comes the fun part!
As funny as it sounds, the problem turned out to be the DIP switch to switch bank 0 and bank 1
It was defective!