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Thread: SOL-20: Remapping Personality Module and video from Cxxx to Fxxx

  1. #1
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    Default SOL-20: Remapping Personality Module and video from Cxxx to Fxxx

    Hi All,

    I was just looking at the Cxxx -> Fxxx remapping hack for the Micro-Complex Dual Personality Module.

    I don't have a schematic for the module, but from the description in their manual and the Sol-20 Schematic, it seems that the hack probably consists of simply connecting the inverted /Phantom signal at pin 2 of U14 to the normally high second inputs of the U22 XOR gates for A12 and A13.

    Normally, the XOR gates (U22) are configured as open collector inverters with wire-ORed outputs, pulling input C of the 74LS138 (U34) high when Adress 13 and 12 are low, corresponding to Cxxx. Connecting the (inverted, logic-high) Phantom signal to the normally high second XOR inputs causes A13 and A12 to no longer be inverted during normal operation, now decoding Fxxx instead of Cxxx. At startup, when /Phantom is asserted, the XOR inputs are pulled high, inverting the A13 and A12 address lines, enabling the upper bits of the 74LS138 when the 0xxx block is addressed, and reverting back to Fxxx after 4 read cycles. This mod would put the ROMs at F000/F400, the 1K system RAM at F800, and 1K video RAM at FC00.

    So, can anyone have a Dual Personality module confirm that the module simply connects the two pins with a switch? The pins are A15 and A14 on the connector, confusingly referring to the pin numbers, not the address lines.

    Also, why did Micro-Complex use pins A15 and A14, which require cutting connector pins on the PCB and cutting traces for original modules to work (such as in this thread)? It would seem to make more sense to use otherwise unconnected pins, such as A1 and A2 on the connector, which would simplify the mod to just adding in a couple of wires, without any need for desoldering pins or cutting traces.

    Dave
    Last edited by dfnr2; August 20th, 2019 at 08:10 AM.

  2. #2
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    Quote Originally Posted by dfnr2 View Post
    Hi All,


    Also, why did Micro-Complex use pins A15 and A14, which require cutting connector pins on the PCB and cutting traces for original modules to work (such as in this thread)? It would seem to make more sense to use otherwise unconnected pins, such as A1 and A2 on the connector, which would simplify the mod to just adding in a couple of wires, without any need for desoldering pins or cutting traces.
    Whoops, never mind. A1 and A2 have +12V and -12V on them. Looks like all the pins are actually used, although the PGM0-3 lines on B1-B4 seem to be for in-situ factory programming of the boards, and don't seem to be used in the SOL-20 system, so might still have been better candidates.

    In fact, PGM1 and PGM2 (B2 and B3) are pulled to +5V on the via pullups in at the PM design in the SOL manual. These are not connected at the main board, so it appears that using B2 and B3 would permit a 2-jumper mod on the mainboard without having to modify any pre-existing modules to work with the modded mainboard.
    Last edited by dfnr2; August 20th, 2019 at 08:51 AM.

  3. #3

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    There is a dual personality module available:

    https://www.ebay.com/itm/Processor-T...8AAOSwdHpb9ovo

    I'm not sure if this is a version of the Micro-Complex one or not. In any case it manages to do it without the requirement for any changes on the motherboard, but I'm not sure if it does what you require for the address range re-mapping ?

  4. #4
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    Quote Originally Posted by Hugo Holden View Post
    There is a dual personality module available:

    https://www.ebay.com/itm/Processor-T...8AAOSwdHpb9ovo

    I'm not sure if this is a version of the Micro-Complex one or not. In any case it manages to do it without the requirement for any changes on the motherboard, but I'm not sure if it does what you require for the address range re-mapping ?
    I've seen that. It uses a pair of 27c16 EPROMs and a toggle switch to select between two personalities. However, it cannot remap the ROM without a main board mod.

    Since I couldn't find any open source Personality module design on the web, I laid out a personality module that uses a single (E)EPROM, and allows selection of one of 8 images using a DIP switch. It can take a 27c256, 27c128, 27c64, or the 28c counterparts. When searching for info on the personality modules, I came across the description of the Dual Personality module and the Cxxx->Fxxx remapping, which I thought might be useful to include.

  5. #5

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    Quote Originally Posted by dfnr2 View Post

    Since I couldn't find any open source Personality module design on the web, I laid out a personality module that uses a single (E)EPROM, and allows selection of one of 8 images using a DIP switch.
    It sounds like a really interesting project for SOL-20 owners. I'm looking forward to seeing what you will do with this.

  6. #6
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    Just sent off the Gerbers. I'll post the results.

    multiple_personality.jpg

  7. #7
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    Looks at lot nicer than that expensive eBay one, too!

    Sounds like they used the same XOR ROM relocate trick I ended up using on the little SDK-80 mezzanine RAM board. I still need to dig into my SOL-20, not looking forward to refoaming the keyboard...

  8. #8
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    Thanks! The forum software seems to have dramatically downsampled the image. The module allows selection of up to 16 1K/2K ROM images. Just in case someone has a system with 1K at C000 and something else mapped to C400 elsewhere, one switch allows the C400 block to be disabled. The last switch will remap the ROMS, 1K system RAM, and video RAM to Fxxx, if 2 wires have been placed on the main board (no cuts). Unlike the Micro-Complex mod, this mainboard mod is compatible with other personality modules without cutting any wires (as described above.)

  9. #9
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    Excellent! Big fan of being able to map around existing memory, as you may have guessed from other projects

    Yeah the forums are horrible with images. I use imgur. You can choose your thumbnail size and get bbcode cut n paste links, nice to be able to choose large when needed, or smaller when not so you don't spam the board

  10. #10

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    Quote Originally Posted by dfnr2 View Post
    I've seen that. It uses a pair of 27c16 EPROMs and a toggle switch to select between two personalities. However, it cannot remap the ROM without a main board mod.

    Since I couldn't find any open source Personality module design on the web, I laid out a personality module that uses a single (E)EPROM, and allows selection of one of 8 images using a DIP switch. It can take a 27c256, 27c128, 27c64, or the 28c counterparts. When searching for info on the personality modules, I came across the description of the Dual Personality module and the Cxxx->Fxxx remapping, which I thought might be useful to include.
    That would be really neat - I'd love one myself. I have a PDF of a a Sol PM modified by MicroComplex which replaces the cassette routines with disk boot routines and makes some other little changes. The PDF is too large to attach here but you are welcome to a copy if you wish.
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