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Thread: Powertran Cortex

  1. #1

    Default Powertran Cortex

    Anyone else on the forum have a Cortex? I just got one and I don't have a lot of information on it yet.

    For those wondering why it is in the TI section, it uses a TMS9995 microprocessor and all of the ancillary support chips are TI as well, even the disk controller (which I am still trying to acquire, as the disk subsystem components were not installed on the machine I got).

  2. #2


    I do, mine's missing the memory map chip, but I'm still trying to find out if that was an option, and also hoping to need some other silicon to put together a worthwhile order for spares. It has however got the disk drive bits in place.
    I lusted after one of these after seeing the articles published in ETI (Electronics Today (International!)) all the schematics (and construction details - it was a kit) are available as PDFs online (I can email you them if you send me a PM). from rusty memory I'm not sure that it wasn't a "Transam" design, so it may share some design heritage with the equally obscure "Wren Executive" also Alasdair McRae-Birch (who still exists) may have had someting to do with it. but I don't know for sure.
    "Don't it always seem to go
    That you don't know what youíve got Ďtil itís gone" (BANG )

  3. #3


    I have all of the documentation that was on Oldcomputers--along with a couple of additional pages that came with mine that weren't in the Oldcomputers archive. As of this morning, I also have the 220 page manual for CORTEX BASIC. A friend of mine in Germany sent it to me when I asked about the machines yesterday on one of the Yahoo groups. He also has one, though his needs a new power supply. Like mine, it does not have the disk subsystem installed. Reading the manuals, I didn't see a way to actually FORMAT or SAVE to the disks listed. Everything was based on booting a program from the disk (which should be in IBM3270 Format?) .

    I understand your long-term lusting after one of these--I've been trying to get my hands on one since around 1988, though the hunt only became continuous in the last ten years or so. . .do you need the BASIC manual?

  4. #4


    I have a frontal cortex, does that count?

  5. #5


    Quote Originally Posted by Ksarul View Post
    I understand your long-term lusting after one of these--I've been trying to get my hands on one since around 1988, though the hunt only became continuous in the last ten years or so. . .do you need the BASIC manual?
    I'd love the basic manual. pdf, I presume (!) if it isn't, it's probably as cheap to get it scanned, as it is to get it photocopied (and a lot cheaper to post) it's probably worth sending a copy to "old" .| "bitsavers" for archiving too. I was going to peek the rom for keywords had it not existed.

    Funny about the disk system possibly not being fully supported, looking at the original article it's "glossed over" a bit I wonder if the code was never properly written - or if they ran out of rom! In 1982 disks were still a minority interest.

    The chap in Germany should be able to rebuild the power supply fairly easily. Even if the transformer's gone away he could replace it with a standard 12-0-12 toroidal one, and wind on the winding for the 5V. It'll probably only be about 20 turns of thickish (about 1mm^2) wire
    I suppose if the supply is missing completely, a little pc one would do the job with the power control wire shorted to ground to turn it on.

    It was way in advance of anything available to the mere mortal at the time!
    "Don't it always seem to go
    That you don't know what youíve got Ďtil itís gone" (BANG )

  6. #6


    The manual version I have is in the form of 220 pages of GIF images. I've been converting them to an editable text document, but the going is slow because the copy I have is relatively bad, so the OCR software needs a lot of help to turn it into something useful. I've finished the first 10% or so of the manual in the last week or so. It is still a lot faster than typing it in manually. I will send you a soft copy as soon as I'm finished with the conversion. If you need it sooner, I can send you the raw GIF images.

    I'll let my friend in on your idea with the power supply. Many thanks!

  7. #7


    sounds like a labour of love!
    Have you considered running a spell checker through it first? (Or is that the way you're doing it anyway) Usually quicker than manually reading & correcting.
    I wonder how many Cortices there are still out there? you've probably got half a week's work per existent machine.
    We owe you!
    "Don't it always seem to go
    That you don't know what youíve got Ďtil itís gone" (BANG )

  8. #8


    Well, I know of three confirmed machines: mine, in the USA, my friend's in Germany, and yours. I also know of one more that was sold on eBay a few months ago. That is more than enough for me to ensure manual preservation. . .and a spell checker doesn't help rebuild mangled tables, unfortunately. I actually just did the pages as raw text dumps and then rebuilt the formatting on my own as a project to keep me busy during random moments of downtime. That way, I finish 2-5 pages at a whack and don't spend enough time on it at any one time to get bored with the task.

    I've also been looking at the memory map chip issue--it should only need the memory mapper if you are trying to build the 256K memory option. The 74LS610 is getting really difficult to find anymore (there is a seller on eBay wanting $30 each for them), but there is also a guy on one of the 6502 forums who designed a plug-in board with relatively common LSI chips to substitute for one (probably would cost more than the $30 chip, but it would be fun). It should be relatively easy to write a VHDL program that works like one as well--then it could be done with a single-chip replacement. I'm just starting to learn VHDL though, so it may be quite a while before I can look at something like that. It would give me VHDL practice since I eventually plan to reverse-engineer the gate arrays for a 99/8 though.

    I am still scouring my parts sources for better prices on them though, since that is the primary option. Most of them only had the 74LS612 though, which is similar but with fewer registers.

  9. #9


    The schematics show the '612 - ebay (uk) item shown below

    Item number: 180273705894

    but I'll check

    Reason I'm doubting it's need, is 4 jumpers (4 address lines?????) near the chip, which I couldn't find on the diagrams, and that mine's missing. I could do with knowing the truth before powering on. I suppose I could lift the board & start "knife & forking" * it through, but I have other priorities at the moment.

    * meter & patience (rather like removing fish-bones)
    "Don't it always seem to go
    That you don't know what youíve got Ďtil itís gone" (BANG )

  10. #10


    I went back to the schematics again--the block diagram lists a 74LS610, but the parts list and the rest of the schematics list a 74LS612. I ordered a bunch of the 612s from a supply house I regularly deal with (Unicorn) just in case. I'll look at the board on mine to see if either chip is installed later today.

    Not sure why they would have been using four jumpers for address lines there, unless they were using 16K memory blocks in a 256K range. That does plot out at least, if two of those jumpers also feed back into the original memory chip array address lines. The other possibility would be that each line activates a single, 64K block--again, the other end of the line will give clues to see if that is the case. If I fish-bone mine to see where they go, I'll post the results here. . .


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