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Thread: Willem programmers and reading late seventies vintage masked ROMS

  1. #11

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    Quote Originally Posted by dave_m View Post
    Tez,
    From the barely legible schematic of the ROM PACK, it seems to me that all three enables (pin 18,20 & 21) are active low. So it looks like the 2716 will not work as-is.

    You may need an adapter that connects pin 21 of the 2716 to Vcc and not to pin 21 of the ROM socket which is grounded along with pin 20.

    Here is the tech manual. The ROM pack is the first schematic. See if you read it the same way. Note that the parts list on P.46 lists the parts as 2716 "PROMs" which is very confusing.

    -Dave

    Sorcerer Technical Manual
    Thanks Dave,

    I have the technical manual (the real thing) so I'll take a look. If that is the case I guess just a 90 deg bent 21 pin and wire jumper to Vcc would do it, right?

    Tez
    ------------------------------------------------
    My vintage collection: http://classic-computers.org.nz/collection/index.htm
    My vintage activities blog: http://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ

  2. #12
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    Quote Originally Posted by tezza View Post
    If that is the case I guess just a 90 deg bent 21 pin and wire jumper to Vcc would do it, right?
    That should work but if you can find a 24 pin socket, maybe you could cut pin 21 off such that it would not make contact with the regular socket underneath?

    You would still need a jumper from pin 21 to pin 24 (Vcc).

    In any case, be careful as pin 21 of the board socket is tied to ground so you do not want a short from there to Vcc. Use a little insulation (electrical tape) to make sure there can be no contact.

  3. #13
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    Quote Originally Posted by dave_m View Post
    That should work but if you can find a 24 pin socket, maybe you could cut pin 21 off such that it would not make contact with the regular socket underneath?

    You would still need a jumper from pin 21 to pin 24 (Vcc).

    In any case, be careful as pin 21 of the board socket is tied to ground so you do not want a short from there to Vcc. Use a little insulation (electrical tape) to make sure there can be no contact.
    As usual, while the rest of us suppose and surmise, Dave cuts to the chase with concrete information You da MAN!

    I just stick the pins of the socket or IC through a piece of paper to insulate bent-out pins from the socket below.

  4. #14
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    Quote Originally Posted by tezza View Post
    Mike at some stage I want to use the burner to replace a couple of my PET ROMS, to get my second board up and running. Can the standard Willem programmer read these ROMS?
    Tez
    Depends on the ROM type and the version of the Willem.

    If you have an original PET with 7 x 6540 ROMs all bets are off; you'd need adapters to let you use 2716 and/or 2732 EPROMs.

    If you have a newer PET version it uses three or four (depending on BASIC version) 2532-compatible ROMs and two (one is the character generator) 2716-compatible ones. If your Willem can handle 2532s then you're in business; if not, there was discussion recently about a simple adapter to let you use 2732s instead ofthe 2532s.

  5. #15

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    Thanks guys,

    That's a big help and has clarified things a lot. The EPROMS should arrive by the end of the week. I'll let you know how I get on!

    Tez
    ------------------------------------------------
    My vintage collection: http://classic-computers.org.nz/collection/index.htm
    My vintage activities blog: http://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ

  6. #16

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    Quote Originally Posted by MikeS View Post
    Depends on the ROM type and the version of the Willem.

    If you have an original PET with 7 x 6540 ROMs all bets are off; you'd need adapters to let you use 2716 and/or 2732 EPROMs.

    If you have a newer PET version it uses three or four (depending on BASIC version) 2532-compatible ROMs and two (one is the character generator) 2716-compatible ones. If your Willem can handle 2532s then you're in business; if not, there was discussion recently about a simple adapter to let you use 2732s instead ofthe 2532s.
    I'll dig out the old board and see what I've got. I suspect it is the newer PET version. Actually it would be good to re-do the character generator too. The one in the spare board at the moment is Swedish, a swap from the working board Anders sent over.

    My working PET has BASIC 2.0. If I can replace the two BASIC ROM chips that are faulty with EPROMS that will upgrade me to 4.0! I'll check the Willem tonight. It seems to list a huge range of ICs. Hopefully it can do 2532s.
    ------------------------------------------------
    My vintage collection: http://classic-computers.org.nz/collection/index.htm
    My vintage activities blog: http://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ

  7. #17

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    Managed to read the mask ROM in the Willem. Made an adaptor (suggested by Pete Turnbull and Dwight Elvery on the classiccmp list) from a socket by bending pin 21 up, and connecting it to pin 12 (ground).

    The faulty ROM read all zeros and a good ROM showed code. Just as it had in the Sorcerer. Diagnosis verified.

    Now to wait for the EPROMS. Getting there...

    Tez
    ------------------------------------------------
    My vintage collection: http://classic-computers.org.nz/collection/index.htm
    My vintage activities blog: http://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ

  8. #18

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    Quote Originally Posted by MikeS View Post
    If you have a newer PET version it uses three or four (depending on BASIC version) 2532-compatible ROMs and two (one is the character generator) 2716-compatible ones. If your Willem can handle 2532s then you're in business; if not, there was discussion recently about a simple adapter to let you use 2732s instead ofthe 2532s.
    Mike,

    Nope, my Willem cannot handle 2532 compatible ROMS (bugger!). Can you point me to the PET discussion you refer to? (there are a lot of PET discussions going on!).

    Thanks

    Tez
    ------------------------------------------------
    My vintage collection: http://classic-computers.org.nz/collection/index.htm
    My vintage activities blog: http://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ

  9. #19
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    Pet Rescue made this adapter:
    http://www.vintage-computer.com/vcfo...23775&p=173003

    You probably have better soldering skills than me, so with the added details you are likely to succeed better.
    Anders Carlsson

  10. #20
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    Quote Originally Posted by tezza View Post
    Managed to read the mask ROM in the Willem. Made an adaptor (suggested by Pete Turnbull and Dwight Elvery on the classiccmp list) from a socket by bending pin 21 up, and connecting it to pin 12 (ground).

    The faulty ROM read all zeros and a good ROM showed code. Just as it had in the Sorcerer. Diagnosis verified.

    Now to wait for the EPROMS. Getting there...

    Tez
    Umm, yeah, isn't that pretty well what Dave suggested, although of course from the other perspective, i.e. replacing your ROM with a 2716?
    Last edited by MikeS; June 20th, 2011 at 12:38 PM.

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