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Thread: TRS-80 Model 4 PAL Source

  1. #21
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    Feb 2009
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    Quote Originally Posted by jltursan View Post
    The Lattice converter was my first option; but it seems that it doesn't like the contents of the U72.jed file. I don't remember exactly; but it moans about a too old part or something like that (doesn't support PAL16L8?), no matter what options I try.
    There must be something wrong with the .jed file. The GAL16V8 can easily emulate the PAL16L8.

    do you mean that you must use the correct brand converter to create the proper GAL file?, if so, as I'm using a Lattice GAL, I'm forced to use the Lattice converter
    Probably. The main array for 16V8's are all the same but there may be differences in the logic control fuses.

    I've derived the eqn file using the Opal Jr suite; but I'm not sure about the result; anyway if you're able to program a PAL using the eqn file I can send it to you, thanks for your kind offer!
    OK, if you think the source file is correct, otherwise send me the equations in a text file or enough info so that I can derive the equations, and the pin names of the 16L8. I will create the .pal and .jed files, then burn a PAL16V8 for you. I can also program the 16L8 type but I don't have any, as they are the older bipolar one-time programmable types. The 16V8 is like an EEPROM and can be reprogrammed if we screw up the equations.

    The 16V8 is designed to be able to replace any of the old style 20 pin PALs and so is useful to have around.

    I like to 'exercise' my ancient Data I/O PAL programmer so there will be no charge for this.
    -Dave

  2. #22

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    Any news and success making a working PAL/GAL?
    Frank

  3. #23
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    Frank,
    I never heard back from jitursan. I did look again at the original .jed file linked in message #10, and I not sure it will work as the target PAL and fuse count information is missing from the file, but perhaps they are not needed. I could regenerate the file using my PALASM software if someone wants it.
    -Dave

  4. #24

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    In fact, using the Opal suite I was able to compile the jed file; but the result wasn't satisfactory. I tried to program a couple of GAL16V8B with my programmer (a Genius G540) without success. Only garbage on screen when booted.
    Right now I have a new and much better programmer, maybe I can try again with the compiled; but I haven't been sure about the original jed, I've never found a single success report related to it.
    Need to check if the programmer, a Wellon VP-498 does support the original PAL ICs...

  5. #25
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    Necroposting here...... but this thread is top of the list for Google when searching for the string 'model 4 u72 gal' so this information should be archived here in this thread, IMO.

    On PDF page 40 of http://www.freepatentsonline.com/EP0126305.pdf we find the actual, original, Tandy-issued design for U72. This design takes into account the possibility of using the 8-bit Z80 bus Z800 chip (Z8108 would be the part number) which drives a new address line, A16. This file contains the equations for the other PAL's in the non-GA model 4, too, making it possible to reproduce those as well.

    I'm planning on running this design through and building up a GAL16V8 JEDEC file that I will put in this thread once I have verified operation.

    BUT, you could use recent manufacture TI TIBPAL16L8 if you can find a reseller with stock; TI made these up until pretty recently.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  6. #26

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    The .jed file makes no mention of device type

  7. #27

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    Ian (Australian super dude also called mav, makes U72 Gal chips , I have a few Pals lying around from model 4's I am sure we can all ask Ian for hex file of the gal to copy and if you want an original TRS-80 Model 4 pal I can mail it to you but I have no means of testing if it is unlocked or not my programmers wont work with it.
    Gaming: i7-8700K, 16GB, 1TB SSD, RTX 2060, Dual 27" LG IPS Monitors.
    Vintage: TRS-80 MODEL 4, 128K RAM, 360K FDD, Gotek USB FDD, FreHD HDD, RS232-WIFI MODEM, DWP-510.
    Programmer: Dell Inspiron 660S i3-3220 with 16GB Ram, running a BK-844USB & EP-2A-88.
    Web Site: https://texastandyrestoration.com/

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