Amiga 2000 Rev 6.3 Diagrom Output

[jasonsbeer]

Finally getting some life out of this machine...here is the diagrom output over serial. What to make of the UDS/LDS test fails? The lines beep out fine between agnus and 68000. Both Agnus and 68000 both tested fine in another machine.

I'm looking at the bits on the RAM reports and there is some crazy stuff going on there and I don't see a pattern. (edit - well, I do see a pattern, it reads the exact wrong value back for each test at each memory location, but doesn't appear to be a specific bit or bits) Diagrom goes on to stop due to no memory found.

Amiga DiagROM V1.2 - 13-Aug-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 FAILED
  - Test of writing word $FF00 to $400 OK
  - Test of writing word $0000 to $400 FAILED
  - Test of writing byte (even) $ff to $400 OK
  - Test of writing byte (odd) $ff to $401 OK
- Parallel Code $fd - Start of chipmemdetection

Addr $00000400
       Write: $AAAAAAAA  10101010101010101010101010101010
        Read: $FBFFFBFF  11111011111111111111101111111111  FAILED

       Write: $55555555  01010101010101010101010101010101
        Read: $FFFFFFFF  11111111111111111111111111111111  FAILED

       Write: $F0F0F0F0  11110000111100001111000011110000
        Read: $F3F0F3F0  11110011111100001111001111110000  FAILED

       Write: $0F0FF0F0  00001111000011111111000011110000
        Read: $0F0FF3F0  00001111000011111111001111110000  FAILED

       Write: $00000000  00000000000000000000000000000000
        Read: $03000300  00000011000000000000001100000000  FAILED
Addr $00008400
       Write: $AAAAAAAA  10101010101010101010101010101010
        Read: $FBFFFBFF  11111011111111111111101111111111  FAILED

       Write: $55555555  01010101010101010101010101010101
        Read: $FFFFFFFF  11111111111111111111111111111111  FAILED

       Write: $F0F0F0F0  11110000111100001111000011110000
        Read: $F3F0F3F0  11110011111100001111001111110000  FAILED

       Write: $0F0FF0F0  00001111000011111111000011110000
        Read: $0F0FF3F0  00001111000011111111001111110000  FAILED

       Write: $00000000  00000000000000000000000000000000
        Read: $03000300  00000011000000000000001100000000  FAILED
Addr $00010400
       Write: $AAAAAAAA  10101010101010101010101010101010
        Read: $FBFFFBFF  11111011111111111111101111111111  FAILED

       Write: $55555555  01010101010101010101010101010101
        Read: $FFFFFFFF  11111111111111111111111111111111  FAILED

       Write: $F0F0F0F0  11110000111100001111000011110000
        Read: $F3F0F3F0  11110011111100001111001111110000  FAILED

       Write: $0F0FF0F0  00001111000011111111000011110000
        Read: $0F0FF3F0  00001111000011111111001111110000  FAILED

       Write: $00000000  00000000000000000000000000000000
        Read: $03000300  00000011000000000000001100000000  FAILED
Addr $00018400
       Write: $AAAAAAAA  10101010101010101010101010101010
        Read: $FBFFFBFF  11111011111111111111101111111111  FAILED

       Write: $55555555  01010101010101010101010101010101
        Read: $FFFFFFFF  11111111111111111111111111111111  FAILED

       Write: $F0F0F0F0  11110000111100001111000011110000
        Read: $F3F0F3F0  11110011111100001111001111110000  FAILED

       Write: $0F0FF0F0  00001111000011111111000011110000
        Read: $0F0FF3F0  00001111000011111111001111110000  FAILED

       Write: $00000000  00000000000000000000000000000000
        Read: $03000300  00000011000000000000001100000000  FAILED
Addr $00020400
       Write: $AAAAAAAA  10101010101010101010101010101010
        Read: $FBFFFBFF  11111011111111111111101111111111  FAILED

       Write: $55555555  01010101010101010101010101010101
        Read: $FFFFFFFF  11111111111111111111111111111111  FAILED

[DigitalKeeper]

Lower Memory not found (first 256KB)


First thing to do -> remove ALL socketed ICs - have a look at the socket, clean the socket's; then have a look at the IC Pin's -> cleaning the Pin's is always recommended


reassemble - all fine?


If not -> check ALL Data- & Adress Lines for broken traces...


If all is ok, there might be a problem with the Data Latches or the DRAMs...

[jasonsbeer]

Greetings all-

My question for now is how to interpret the diagrom output for the chip ram test. Being an A2000, I'm only expected a 16 bit output, but there are 32 bits reported? Please help me understand the below output.

Write: $AAAAAAAA 10101010101010101010101010101010
Read: $FBFFFBFF 11111011111111111111101111111111

[jasonsbeer]

Originally Posted by jasonsbeer

Greetings all-

My question for now is how to interpret the diagrom output for the chip ram test. Being an A2000, I'm only expected a 16 bit output, but there are 32 bits reported? Please help me understand the below output.

Write: $AAAAAAAA 10101010101010101010101010101010
Read: $FBFFFBFF 11111011111111111111101111111111

I'm going to partially answer my own question. The bits are read out from high (15) to low (0). I was counting them from low to high, which was causing me a bit of confusion. I ended up pulling all the drams from the board and replaced them one by one to see what happened. I still don't understand why there are 32 bits reported. Maybe its reading and writing the value twice?

At this point, this Amiga will only pass startup tests with ram installed in U501-504. Installing ram in any of the U505-508 slots causes some of the the related bits to fail...as was seen in my original post. There doesn't seem to be a pattern in that the the failing bits will change between power cycles. The drams all test good and I've installed new drams to no effect.

The only signal that differentiates U501-504 from U505-508 is _RAS, which comes from Agnus. I have tested two known good Agnii in this machine and the result is the same. I have pulled, tested, and replaced the buffers and latches. Those are not the issue. All the resistor packs are good. Every trace tones out as good. I've checked Gary and Denise...I'm going to check Paula today.

What am I missing? I don't have a scope to check signals. Until I can get one, I'll probably shelve this machine.