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Thread: Fun with CC40's

  1. #1

    Default Fun with CC40's

    512 KB RAM, <and> blinkenlights...

    Does it get any better?
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  2. #2
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    What do you do with 512kB RAM on that?

  3. #3

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    ...What do you do with 512kB RAM on that?

    Just about anything you might do with a PDP-8.

    Except run up a big electric bill. Easier to move too...

  4. #4
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    Quote Originally Posted by JGardner View Post
    ...What do you do with 512kB RAM on that?

    Just about anything you might do with a PDP-8.

    Except run up a big electric bill. Easier to move too...
    I knew TI was reluctant to produce data storage for the CC40 but that looks like a lot of work just to get DECTape running.

    It is an impressive feat though.

  5. #5

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    Wafertape, ladies.
    That is all.
    (Yes, I have one of them. It works okay last I tested it, though I never used it heavily.)
    I use my C128 because I am an ornery, stubborn, retro grouch. -- Bob Masse
    Machine room: http://www.floodgap.com/etc/machines.html

  6. #6

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    Hi Krebizfan -

    Thanks for the kind words.

    I'm working on a Wafertape emulator - I also need a cartridge RAM which

    allows loading an EA image. This should do it, and then some...

  7. #7
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    Any chance of a better look at the circuit? It would be interesting to see if it could be adapted to a TI-74.

  8. #8

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    Hi byates -

    Unfortunately this scheme won't work with a TI-74. The CC40 cartridge port has two paging

    bits available; as intended by the designers it will support 128K. I use those two bits as an

    I2C bus to control a MCP23008 (a so-called 'port expander') to specify the high 4 bits of the

    512K address. As presently constituted 23 bits are available; the scheme could address 8M.


    The 74 cartridge port does'nt have paging bits; something else will have to be concocted.

    There are multi-page '74 ROM cartridges; it's possible to use <Writes> to ROM to control

    paging. For RAM, I think you'd need to decode a specific address and use that for page

    control.

  9. #9
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    JGardner, thanks for the info. Looks like I will have to dig deeper if I want to expand it.

  10. #10

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    byates -

    Perhaps the easiest thing to implement on the '74 would be to use the Dockbus port pins

    to set the high address bits of cartridge RAM, using what TI calls "non-standard I/O mode",

    aka BAV high & HSK low. Writes to the data port then appear immediately on the port out-

    put pins.

    Of course this means some wires (4) between the Dockbus port & the cartridge, and you'd

    be limited to 512K, but I can't see any reason why it would'nt work fine, & the price would

    be pretty hard to beat... Come to think of it, put a crowbar in your wallet & spring for an

    extra wire & you could toggle BAV too, for a cool MB.


    Think I'll try it - If you don't beat me to it...

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