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  • falter's Avatar
    Today, 05:25 PM
    falter replied to a thread Poly 88 case in S-100
    Thanks Dwight. I believe my Poly case still has the cassette board.. I found a picture that purports to be one.. it's a rather small board with a...
    22 replies | 937 view(s)
  • falter's Avatar
    Today, 04:22 PM
    falter replied to a thread Poly 88 case in S-100
    Thanks guys. I'd love to try making a DG640.. but have not been able to find any artwork. The microbee forum is really difficult to get through...
    22 replies | 937 view(s)
  • falter's Avatar
    Today, 02:06 PM
    falter replied to a thread Poly 88 case in S-100
    I do have a few interesting S100 cpu boards to play with.. one is an Australian DG680.. a Z80 board but the only problem is I'm missing the ROM and...
    22 replies | 937 view(s)
  • falter's Avatar
    Today, 11:55 AM
    falter replied to a thread RCA Microtutor in Other
    Personally I'm happy.. I didn't pull off the smoking deal you got.. but at least it means I didn't wildly overpay for mine. My documentation is a...
    11 replies | 610 view(s)
  • falter's Avatar
    Today, 09:40 AM
    falter replied to a thread Poly 88 case in S-100
    Question: What are the bare essentials to have a running Poly 88? I know about the CPU card and Video interface.. did you need a RAM board or...
    22 replies | 937 view(s)
  • falter's Avatar
    Yesterday, 03:53 PM
    falter replied to a thread RCA Microtutor in Other
    I'm quietly hoping this one goes over $500. That's what I ended up paying for mine, including the CPU card which we eventually found.
    11 replies | 610 view(s)
  • falter's Avatar
    Yesterday, 03:40 PM
    You're right to a point.. there's nothing practical these vintage machines can do that can't be done or emulated by modern, much more useful...
    35 replies | 1799 view(s)
  • falter's Avatar
    Yesterday, 08:37 AM
    I am in a quandary of such right now. I have almost all the original parts to build an Altair 680 save for case.. and vintagecomputermuseum is...
    35 replies | 1799 view(s)
  • falter's Avatar
    February 20th, 2018, 04:28 PM
    I bought one of these off ebay for $50. Not really into PC compatibles but this one is really cool.. the steel case, colour etc are awesome. But...
    0 replies | 65 view(s)
  • falter's Avatar
    February 20th, 2018, 02:00 PM
    Aha! According to the schematic and artwork, pin 3 (A6) should go directly to IC6 pin 11. By default, pin 3 is high, but there is no signal on...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 20th, 2018, 08:36 AM
    Did some more testing with the cursor board. For an experiment, I left the directional switch on subtract, and then manually shorted pins 30 and...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 19th, 2018, 08:18 PM
    I am really hoping it doesn't come to this, but I may have to redo a couple of these boards. The TVT boards are supposed to be interchangeable -...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 18th, 2018, 07:07 PM
    Don had me connect the self test to board connector pin 21 as well as pin 15 of IC10 on the memory board. I sent this back to him. ...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 18th, 2018, 01:29 PM
    Well the interesting thing is Line 27 and 30 are both supposed to be open for one direction and shorted for the other. However, 27 is always open no...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 18th, 2018, 12:43 PM
    Yeah I was off on that one. I've made another discovery. What I'm interpreting as 'multiple' cursors is actually one cursor continuously moving...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 18th, 2018, 11:09 AM
    Hmmm.. I wonder if I'm the victim of a typo here. Check out the schematic: http://www.swtpc.com/mholley/TV_Typewriter/page_16.pdf It shows C3 as...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 18th, 2018, 10:55 AM
    Made a tiny bit of progress. I began to be suspicious of these 74197 counters (which are all dated 1969 or 1970) on the cursor board. So I started...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 17th, 2018, 07:38 PM
    Hmph. So it seems like the circuit that handles KEYPRESSED is ok. Everything seems to feed through to the input clock line for IC2. And yet...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 17th, 2018, 04:43 PM
    Nevermind.. it's doing what it should be. There is a clock pulse on pin 1, there is a pulse on pin 2 when I ground KEYPRESSED. Following pin 3 to...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 17th, 2018, 04:31 PM
    Okay so, trying to teach myself a bit here, trying to investigate why there's no character entry. I read the explanation carefully of what happens...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 05:57 PM
    Ah.. my bad. The instructions say pressing home *forces* A6 high. So it would always be adding a logical 1 to whatever else I set up. Thus if I...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 05:17 PM
    Scratch my page A/B switch problem. The parts placement diagram, which I have been relying on for switch positions, might be wrong. On the parts...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 05:15 PM
    No dice. KP is definitely held high but when I ground there's no action. There's also some other weird stuff going on. For example, home/clear...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 03:51 PM
    Yup.. here it is from the manual: "Any keyboard will work with the TV Typewriter, provided it is connected and encoded in such a way that you get...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 03:47 PM
    I have a bunch of IN4001s, would that work? Also I've discovered an issue with the keypressed pin (pin 22 or C on the actual connector). The...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 03:18 PM
    Yeah I screwed up. I was looking at the parts list for the teletype circuit. Doh. The actual diode I installed that handles power is a 1N4736. ...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 11:34 AM
    I think Pin 22 connects to C.. I'll check that. Also I just had a thought.. I don't know if the diode I picked for the encoder is correct. The...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 10:47 AM
    I'm still figuring it out. I cannot get it to show any waveforms. I think I've set it up correctly but still wading through the (awful) manual. ...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 09:46 AM
    I jumpered A1-A5 to ground and did a Home test. Voila.. blank screen! I do appear to have one bad 2524 in there.. when I was firing it up initially...
    630 replies | 36770 view(s)
  • falter's Avatar
    February 16th, 2018, 06:30 AM
    At the prompting of Don I decided to add the 2524v ahift registers to see what happened. They do change the behavior of the machine a bit.. now if I...
    630 replies | 36770 view(s)
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The Ebay Follies

by falter on June 25th, 2017 at 11:09 AM
All hail the $3000 Apple II+!

http://www.ebay.com/itm/142424958928
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