Amiga 1000 - Black screen after loading kickstart

[schlika]

Hi,

I was just given an A1000 ... I am super happy, this was my first Amiga ! It is a plain A1000, with the 256k extension but nothing else. I had some work cleaning it, but it worked for about an hour.

Now it seems to work fine, shows the kickstart hand screen, reads the kickstart floppy I just wrote and tested using a greaseweasel (also tested with an old kickstart 1.2 floppy), but dies on a black screen (video off apparently, no more video signal) never showing the Workbench "hand".

I burnt a pair of A1000 DiagRom, and here is the output from the serial port :

???U



Garbage before t @???U



Garbage before this text was binary numbers: 1, 2, 4, 8, 16, 32, 64, 128, 240, 15, 170 and 85

To help you find biterrors to paula. Now starting normal startuptext etc



Amiga DiagROM V1.1 - 06-Jan-19  - By John (Chucky/The Gang) Hertell





Testing if serial loopbackadapter is installed: <> NOT DETECTED

- Parallel Code $ff - Start of ROM, CPU Seems somewhat alive

    Checking status of mousebuttons for different startups: 

            

    Set all Interrupt enablebits (INTENA $dff09a) to Disabled: Done

    Set all Interrupt requestbits (INTREQ $dff09c) to Disabled: Done

    Set all DMA enablebits (DMACON $dff096) to Disabled: Done



Testing if OVL is working: OK

- Parallel Code $fe - Test UDS/LDS line

  - Test of writing word $FFFF to $400 OK

  - Test of writing word $00FF to $400 OK

  - Test of writing word $FF00 to $400 OK

  - Test of writing word $0000 to $400 OK

  - Test of writing byte (even) $ff to $400 OK

  - Test of writing byte (odd) $ff to $401 OK

- Parallel Code $fd - Start of chipmemdetection

(the A1000 version of DiagRom is limited due to the size of the rom, it only outputs to serial (I hope) and is stuck at version 1.1)

It looks like DiagRom kinds of hangs while trying to detect chipram ?

I check voltages, all ok,I tried with or without the front 256k ram extension, I tried swapping the CIA's, no difference.

Do I "simply" have dead memory chips ? can this hang the DiagRom ?

This machine has no fastmem, just the basic 256k/512k of chip, and looking at DiagROM.s it seems that the test after chipmemdetect is trying to find some fastmem, may that part hang instead of the previous one ?

Do you see anything else ?

Thanks for helping !

[r.cade]

Oh, no... Sorry to hear. I had that happen recently, but it turned out I had a corrupted kickstart disk. It sounds like you already checked that, though.

I thought the Amiga tested the WRAM and chip RAM at startup, but maybe it's possible there is still some bad. I know it doesn't do any checksums when loading kickstart.

[R4M]

I would try a different kickstart disk first. What happens on a keyboard reset after the black screen appears?

[Vypr]

Could possibly weck what screen resolution the Workbench is loading into in case it's going to a res the monitor can't handle?

[schlika]

- I did try three different kickstart disks (one that worked before)
- Keyboard reset seems to loop trying to execute the loaded kickstart (does not ask for kickstart again)
- I tried both db23 & composite, both are black

[R4M]

When the BootROM does not ask for a Kickstart disk after a reset,the checksum of the WOM content is OK. So the problem might be after the Kickstart is loaded. Maybe a bad 256KB Ram Expansion.That is not checked at bootup in the BootROM

[schlika]

OK, that is an interesting point, thanks. I tried with & without the 256kb extension, same issue, so probably the mainboard chip ram may have issue ? Would that freeze the diagrom ?

[Signman]

I did have this too but in my case in was an issue with monitor syncing with the adapter on rgb port. On a amiga crt, no problem.

[schlika]

Well ... you are absolutely right ! Plugging the 1081 got me a picture ! I feel stupid, but relieved it was only that.

Strangely enough the "Kickstart" and "Workbench" hands are using different video modes apparently, and my 2410, that ate everything I ever threw at it, was unable to display it.

Fortunately, I quickly soldered a cable for my old Gonbes (I updated it to the new gbs-control firmware) and I get a great output on the 2410 now.

Thanks for your help !!