A500 ROM Switcher Woes

[Huxley_D]

So in my ongoing "upgrade the A500 beyond any semblance of sanity" project, I've tackled the ROM options. I bought a ROM switcher used on eBay, and (to his credit) the seller was upfront about the fact that the switcher hadn't worked well in his A600, so I rolled the dice and bought it anyway. I've also purchased a brand-new licensed ROM 3.1 chip from AmigaForever. Here's what happens:

* With the original ROM 1.3 chip on the motherboard, everything works as normal
* With the ROM 3.1 chip on the motherboard, I get a jittering purple garbage display for a moment, and then a blank purple display forever
* With the ROM 3.1 chip in the ROM switcher (by itself), I get the classic "Insert Disk" animation but the floppy drive doesn't respond to any inserted disks and I can only get this far if I have the jumper on the switcher enabled (if the jumper is left off, I only get a blank screen)
* With both the ROM chips (1.3 and 3.1) in the ROM switcher, I get a blank screen on power-on, though the LED on the switcher's LED will turn on / off when I hold the CTRL-Amiga-Amiga keys

Other than just assuming the ROM switcher is FUBAR and needs to be replaced, any suggestions on next-steps here? It seems odd to me that the 3.1 chip doesn't work by itself on the motherboard...

Thanks!

Huxley

[psxphill]

Other than just assuming the ROM switcher is FUBAR and needs to be replaced, any suggestions on next-steps here? It seems odd to me that the 3.1 chip doesn't work by itself on the motherboard...

Revision 5 and earlier A500 boards are wired up incorrectly for 512k roms, so the upgrade roms were sold with a wire between two pins. If you have a Revision 6a and later require you to remove the wire.

I imagine all your problems are related to this somehow.

[SACC-guy]

Just in case...
Don't The roms for the 600 and 1200 have ide and  pcimca built-in?
could explain why the rom isn't working on the motherboard?
Don't you need the 500/2000 rom?
 (and yes the 500 version had a wire you left alone or cut based on what version motherboard you had)

[Huxley_D]

Revision 5 and earlier A500 boards are wired up incorrectly for 512k roms, so the upgrade roms were sold with a wire between two pins. If you have a Revision 6a and later require you to remove the wire.

I imagine all your problems are related to this somehow.

Oh, interesting! Looking at the ROM chip I bought (here's the URL: http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=40_99&products_id=157 ) made me assume it would be plug-n-play, but now that I'm looking at my A500's motherboard I see that it's a Revision 5 board. The ROM I received from the link above doesn't have any wires jumping any of the pins, but the label does specify that it's for the A500/A600/A2000. Oddly, the chip didn't come with any real installation instructions, other than a folded-up sheet of paper explaining that it needs to be inserted backwards in certain German A2000's. Nothing at all about the A500, shorting pins, etc.

Weird. I suppose your suggestion would account for why it seems to work when its installed in the switcher with the "512k" jumper enabled though... I just wish it would actually boot - it totally ignores any bootable disks I insert (I can hear the floppy drive periodically checking though), even when I've held both mouse buttons down and manually selected the floppy drive as the first boot device.

[mechy]

Just in case...
Don't The roms for the 600 and 1200 have ide and  pcimca built-in?
could explain why the rom isn't working on the motherboard?
Don't you need the 500/2000 rom?
 (and yes the 500 version had a wire you left alone or cut based on what version motherboard you had)

500/600/2000 3.1 roms are all the same and work with ide etc. early 2.05 rom(27.299) is missing ide/pcmcia support,27.300 and 27.350 had ide/pcmcia support.
all the above work in 500,600,2000  
A1200 uses 2 roms,totally different from 600 roms. 1200 roms have ide/pcmcia support.
and yea,add or remove wire depending on 500 rev.

[psxphill]

Weird. I suppose your suggestion would account for why it seems to work when its installed in the switcher with the "512k" jumper enabled though... I just wish it would actually boot - it totally ignores any bootable disks I insert (I can hear the floppy drive periodically checking though), even when I've held both mouse buttons down and manually selected the floppy drive as the first boot device.

Try swapping the two CIA chips round and see if anything changes in 1.3 & 3.1.

Kickstart 1.x and 2.x+ use the CIA differently, and while the chips are supposed to be identical, it is possible that you have a damaged one that works enough for 1.3 but not 3.1. In which case swapping them may have some effect. It's possible that it's another chip but CIA's are a good starting point because you are guaranteed to have two of them.

I'd also try using the 3.1 without the switcher by adding the wire, in case it's causing the problem.