Problem with H4 not booting (zChris's board)

[zChris]

Hello,

I "fixed" A12 like you see on the picture. But the problem is still there were it is a white screen and i nothing happens when i press the reset.

a12fix.jpg (459.54 KiB) Viewed 4616 times

[exxos]

Have you checked all address lines are connected in top of the glue pins ?

[zChris]

Yes, i get all connection with all the adress to the GLUE. Should i redo the "checking for adress 0" again ?

[exxos]

Yes, i get all connection with all the adress to the GLUE. Should i redo the "checking for adress 0" again ?

Yeah you can check the address to see if they all stuck on zero.. Also check what the data bus is doing..

The first bus access is the cpu reading address zero, the ROM should put data on the bus, and after I think 2 or 3 bus cycles the CPU should have gotten a jump instruction from the ROM to start booting TOS. But for some reason the CPU never gets that instruction from ROM.

[PhilC]

@zChris a reminder just in case, both EmuTOS 256k and Tos2.06 will need the decoder fitting

[exxos]

@zChris a reminder just in case, both EmuTOS 256k and Tos2.06 will need the decoder fitting

I kinda assumed he had a working 104 ROM as his machine was booting before and the ROM has your sticker on its but he said he made no changes to the board at all anyway..

[PhilC]

@exxos he did say he broke a pin on one, so it was just in case he broke that one.

[exxos]

@exxos he did say he broke a pin on one, so it was just in case he broke that one.

So the ROM has been changed then ? It wasn't that board you put the socket in backwards was it ?

[PhilC]

@exxos lol no, that was the Alpha board

[derkom]

a12fix.jpg

Be careful about trying to power a board over dupont cables like that. I ran into all sorts of problems when doing that, because of voltage drop. If you've moved your PSU away like this, check your 5V on the board again and make sure it hasn't dropped too low to boot.