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Thread: HX-20. It's a Trap!

  1. #1

    Default HX-20. It's a Trap!

    This happens whenever I select Basic at startup. Anyone have a troubleshooting suggestion?
    hx20.jpg

  2. #2
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    Quote Originally Posted by Towmater View Post
    This happens whenever I select Basic at startup. Anyone have a troubleshooting suggestion?
    hx20.jpg
    Try this: https://files.support.epson.com/pdf/hx20__/hx20__t1.pdf
    Surely not everyone was Kung-fu fighting

  3. #3
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    Yes, doing the full reset (CTRL+@) can help. Possibly, you've got corrupt data in the lower RAM, and BASIC is trying to do something there and getting a problem.

    Does MONITOR seem to work? If it does, then you need to look at the code around DFD1 and DFD6, and see what it's trying to do. I'm pretty sure that these addresses are within the BASIC ROM code, and they are prob setting things up in the lower RAM area.

    A, B and X (indeX) are the registers, C is the Status reg, S is the Stack Pointer and P is the program counter.

    At this moment, the next memory address is DFD6, so the prog may be trying to do DFD4. Interested to know what value is in DFD1.

    Further looking in my manual says that ROM area D000-DFFF is for Menu, Monitor and virtual screen routines, so the values you show may merely reflect the 'Trap' code.

    Again, does MONITOR word. Does this allow the usual D command to Dump memory contents. Addresses 00 - 4D are I/O ports and should be 'Protected'. If you try to access them, does it say 'Protected'? Do you get normal Dump for addresses past 4D?

    Geoff
    Vintage Devices: Epson HX-20/TF-20, Amstrad PCW 8256 (with extras), 386 and 486 PCs with 5.25 and 3.5 floppy drives, Pentium 75 with Roland LAPC-I midi card

  4. #4

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    Thanks to you both. The Ctrl-@ reset seems to have cleared up the issue. Does anyone know if there is a binary file for a word processor that I could place in the empty rom socket?

  5. #5
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    Nice to hear that you've got past that little problem. I get a variant of that when swapping between BASIC and FORTH (in ROM) in that if I've used BASIC, and then try to run the FORTH and try to do a 'warm' start there's stull stuff from BASIC in the lower (system) RAM and I get a similar 'trap'.

    There is a ROM image about for the WP 'SkiWriter'. One was posted a little shile ago on another forum, I'll hopefully attach it here.

    Geoff
    Attached Files Attached Files
    Vintage Devices: Epson HX-20/TF-20, Amstrad PCW 8256 (with extras), 386 and 486 PCs with 5.25 and 3.5 floppy drives, Pentium 75 with Roland LAPC-I midi card

  6. #6
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    Just for information, I've had a look inside the SkiWritr zip file and I note that it contains an 8k .BIN file, and looking inside this file it does look like a memory image file suitable for loading into an 8k ROM using the memory range 6000-7FFF which would be the same as the range used by the Forth ROM that I have installed.

    Note that if you create such a ROM, and install it, there may well need to be an install process involved. In the case of my Forth ROM, this involves using the MONITOR to change a single byte. I do not know that the SkiWriter will need exactly the same, but it could well. If you get to that stage, let me know and I'll set out the instructions in full.

    Geoff
    Vintage Devices: Epson HX-20/TF-20, Amstrad PCW 8256 (with extras), 386 and 486 PCs with 5.25 and 3.5 floppy drives, Pentium 75 with Roland LAPC-I midi card

  7. #7

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    The monitor is run when a trap interrupt is generated due to a program overrun.
    The message Trap! will appear on the second line of the screen, below the command prompt.

    The HX20 will enter the monitor mode when a command which is not defined for the 6301 CPU is executed. Should this happen the monitor will display the message Trap! on the second line.

    In short: either your BASIC ROM is corrupted or modified or maybe missing...
    Has it ever worked for you? These systems were popular in lab/industrial environments and have been known to be modified.

  8. #8

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    Many thanks, Geoff. I'll report back once I've cooked an eprom, and double checked that one can be simply installed. (I noticed a pin-swapping board is needed to use an eprom in a Tandy M100, so I need to check if a similar situation exists with the Epson.)

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