Amiga 1000 crashes after loading kickstart

[bwldrbst]

I picked up a non-working Amiga 1000 last weekend, mainly to get an original keyboard and mouse for my working A1000.

The non-working A1000 runs through the POST colours and makes the startup sound OK. It will prompt for a kickstart disk. It appears to load kickstart but instead of prompting for workbench it flashes a bit of garbage then shows a solid purple screen.

According to this page: http://members.quicknet.nl/rhm.herol...rs_meaning.htm a magenta screen indicates "single-task or cold-start initialization failed" which sounds like it fits with what I'm seeing.

I have tried swapping the floppy drive with my other A1000 (30 &@*^!#% screws!) and an A1200. Both do the same thing and the drive from the non-working A1000 works fine in another Amiga.

Removing the 256K RAM expansion made no difference.

The machine also came with an Action Replay cartridge. On my working A1000 I can bring up the AR console and run a memory test as soon as kickstart is loaded. The AR doesn't respond on the non-working machine.

The A1000 is a PAL model with no daughter board and no internal modifications. Apart from a bit of dust it looks pretty clean and there isn't anything obviously wrong that I can see. I've attached a picture of the motherboard.

To me this sounds like a problem with RAM or the memory used to store kickstart. Does anyone have any suggestions for getting this old girl running?

Cheers,

Andrew

[Toni Wilen]

What happens if you keyboard reset it after KS disk has been loaded? Does it ask for KS disk again or just crash again or nothing happens?

Magenta color most likely means nothing in this case, it is most likely garbage written to custom registers. (and afaik magenta error color is only in KS2.0+)

[bwldrbst]

Originally Posted by Toni Wilen

What happens if you keyboard reset it after KS disk has been loaded? Does it ask for KS disk again or just crash again or nothing happens?

If I reset it will just ask for the KS disk again.

Originally Posted by Toni Wilen

Magenta color most likely means nothing in this case, it is most likely garbage written to custom registers. (and afaik magenta error color is only in KS2.0+)

Fair enough. I thought it might have some meaning due to it being very consistent.

[Toni Wilen]

Originally Posted by bwldrbst

If I reset it will just ask for the KS disk again.

I think this points to Kickstart RAM/WOM fault or fault in related signals (write protected when it should not, ROM overlay etc..)

Boot code asks for Kickstart if it is not yet loaded. I don't remember how it tests it (I need to check it again) but it isn't full checksum check because KS disk with bad checksum is accepted and it does boot once before red screen appears.

Did you try swapping CIA chips? (If it is CIA ROM overlay signal fault). It can't be anything major because KS disk loading works and basic A1000 boot ROM tests pass.

[bwldrbst]

I've just tried swapping the CIAs around and it made no difference.

At least I didn't make anything worse...

[bwldrbst]

A bit more messing around...

I tried leaving the machine running for a couple of hours, rebooting every now and then, to see if anything changed as it heated up. None of the ICs felt overly warm to touch.

A couple of times I got different coloured screens after kickstart loaded, once aqua and on the next reboot yellow. After that it was back to purple.

[xArtx]

I don’t usually go pushing my own videos after the fact, but this is for you
[ Show youtube player ]

Unless of course you can find the right RAM chips!
The mod makes a mess of course, and changes it fundamentally to a Kickstart ROM
machine with less RAM, even after the 256k expansion, than a trapdoor expanded A500.

[bwldrbst]

That looks pretty cool, I had wondered what was involved in getting a ROM in there. Why does it end up with less memory? Is the ROM mapped into the same address space as the RAM?

Before doing something like that I'd rather find out what the actual problem is.