Problems at HX-20 Restart

    After many trials and following troubleshooting tips suggested, the system display remains after many attemps, as follow:


    -
    ----------------------------------------

    Break

    ----------------------------------------

    A=10 B=BD X=E0D7

    ----------------------------------------

    C=D9 S=0112 P=011B

    ----------------------------------------

    The system behaves as this:

    Start by switch on : display appears after the "beep" tone" that I interpreted as encouraging, but:


    Switch off doesn't clear the screen

    Push on the reset button clears the screen


    Some info about the machine:

    Serial: 010884.

    Should be running BASIC V1 and has the opening over the 6301 VOP C63010 CA

    Basic M64030AA ROMS:

    ROM0: A2X145

    ROM1: A2X144

    ROM2: A2X139

    ROM3: A2X140

    ROM4: Empty

    RAM 0,1,2,3: M16010C (x4)

    Dip switch settings: OFF ON ON OFF : French Keyboard (Membrane type)

    Power supply: new sub-Cells (1500mAh) installed; recharged using the original transformer.

    Battery circuit checked up to the capacitors

    Flexprint and other flat ribbon cables checked.


    Any suggestions are welcome and I would be more than happy to see this machine up-and-running again.

    Many thanks in advance.


    Andre

    The only things I can see are:

    • The program pointer P is at 11B. This is the address of the NMI vector.
    • the stack pointer S contains 112, which would be the address of IRQ1 ICF

    You can check whether the ROMs are plugged in correctly and in the correct order.

    They should be

    ROM0: M64030AB BASIC1R0 (a V1.1 BIOS would have BASIC1R1)

    ROM1: M64021AB BASIC1R0

    ROM2: M64022AB BASIC1R0

    ROM3: M64023AB BASIC1R0

    (you listed the manufacturing codes, not the ROM numbers)


    You should also remove any accessories like cassette, expansion module or internal RAM expansion (if present) and switch the printer off to minimize errors during system checks.


    Next step could be to borrow a set of known good ROMs and replace them to see whether the ROMs are damaged. Same with the 6301 coprocessor.


    If the monitor works, you could also inspect tor lower system RAM for unusual content.