A500 Won't Recognize 3.1 ROM

[jammarob]

Howdy!

I'm running into a strange issue with my Rev 5 Amiga 500. I can't seem to get it to boot from a 3.1 ROM (black screen). The EPROM has been modified as required to work in a rev 5 motherboard.

The system will boot to it's stock 1.3 kickstart with no issues. Here is what I have tried:

*EPROM tested in another Amiga 500 and works.
*Reseated all socketed ICs.
*Replaced CPU with known good CPU.
*Tried a different 3.1 ROM that is also tested as good.

Here is the keyboard LED error code I see:
https://www.youtube.com/watch?v=gBcCypJiNSc

If both mouse buttons are clicked to enter the menu, it loads part of the menu and then freezes:



I am at a loss. Any ideas? I don't recognize the keyboard error either

[Oldsmobile_Mike]

Can't read your screenshot.

So what you're saying is:

- The ROM works fine in other A500's.
- The Amiga works fine with other 3.1 ROM's.

That seems weird, so the only compatibility issue is between that particular A500 and that particular ROM?  You burned it yourself?  Stock, no changes?


Edit:  maybe I mis-read your post.  Are you saying the A500 won't work with any of the 3.1 ROM's you've burned?  I hate to say it, but have you tried one from AmigaKit?  You can buy one new for under $20 USD.  Easy way to troubleshoot is to test with a new one.  

[Oldsmobile_Mike]

http://en.wikipedia.org/wiki/Power-on_self-test#Amiga_keyboard_LED_error_signals

[jammarob]

I actually bought both EPROMs from Amigakit, and this particular A500 will not boot to either, but the EPROMs work on another Rev 5 A500.

I can only get this particular Amiga to work with its stock 1.3 KS ROM

[danbeaver]

Have you contacted Amigakit and opened a ticket with them?

[jammarob]

I don't want to do that because the EPROMs work fine in a different rev 5 Amiga. I don't think the issue is with the 3.1 ROMs themselves.

[ElPolloDiabl]

You must need to do this modification:

http://www.area536.com/projects/amiga/upgrade-amiga-500-kickstart-from-12-to-31/

[jammarob]

I have done that already

[Oldsmobile_Mike]

Check and re-check the socket?  And check it again, just for good measure?    Another dumb question - you're plugging it right into the motherboard, right?  Not using any kind of ROM switcher?

[jammarob]

Good tip. I'll check continuity between the pins of the EPROM and the socket.

No funky switchers here. Just trying it straight in the board!

[Oldsmobile_Mike]

1.3 is 256K.  3.1 is 512K.  Some kind of addressing issue?  Any weird memory expansions in the system?

[jammarob]

The modification to the 3.1 ROM (mentioned here) addresses the issue with the larger ROM. It's almost as if it's not bank switching, but only reading part of the ROM data. The incomplete startup menu is really strange.

I have tried it both with and without the Commodore 512K expansion with the same results.

[Oldsmobile_Mike]

It's almost as if it's not bank switching, but only reading part of the ROM data. The incomplete startup menu is really strange.

That's what I was getting at.  I cannot for the life of me remember why you need to do that mod on Rev 5 boards.  Hypothetically speaking, if someone had plugged in a straight 3.1 ROM without doing the mod, is it possible that something on your particular board could have been damaged in such a way that only the older ROM would still work?

But I'd go back to checking the continuity, first.  

[mechy]

Howdy!

I'm running into a strange issue with my Rev 5 Amiga 500. I can't seem to get it to boot from a 3.1 ROM (black screen). The EPROM has been modified as required to work in a rev 5 motherboard.

The system will boot to it's stock 1.3 kickstart with no issues. Here is what I have tried:

*EPROM tested in another Amiga 500 and works.
*Reseated all socketed ICs.
*Replaced CPU with known good CPU.
*Tried a different 3.1 ROM that is also tested as good.

Here is the keyboard LED error code I see:
https://www.youtube.com/watch?v=gBcCypJiNSc

If both mouse buttons are clicked to enter the menu, it loads part of the menu and then freezes:



I am at a loss. Any ideas? I don't recognize the keyboard error either

If the continuity checks out you may check the eprom speed, i wouldn't think it would be the problem but if they are using slow eproms timing might be right on the edge.

[jammarob]

Continuity checks ok.

I'm stumped.

At this point I think i'll just pick up another A500