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About Jeff_Birt

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    Space Invader
  1. The 'sense' line is an output of the Commodore C2N datasette. It was made use of by the Commodore 64/VIC-20 originally. The TI-95 does not have any provision for this as far as I am aware. Since the CI-7 tape interface was designed for use with a normal cassette deck which would not have had a key sense output. It is curious though that TI-99/4a has an input pin that acts as though it was made for that purpose given that they had a similar three wire analog tape lead, though they did use a DB9 connector on the computer side of it so there would have been extra pins for that purpose. Maybe they had thought at one point about their own tape deck? Sadly, I don't know much bout the 99/4a.
  2. The big IC is a 'line driver' which just means it has higher current outputs for driving a heavier load. I suspect they used it as a buffer and/or inverter for the 3 I/O lines used. Yes, the TI-95 and TI-74 added two pins to make a 10 pin connector. The extra two pins being a 6VDC input to the calculator (which my interface supplies so when you are using the cassette interface you are not running on batteries) and a 6V output. The cable between the adapter and the CC40 would be different. I recently picked up a CC40 and have not used it yet. I'll look at making a cable for it as well. In the design files linked in the video there is a PDF of the schematic (in case you don't use Eagle) which shows the pin outs of the TI-95 connector and adapter connector. ​If there is interest I'll see about getting a small number of PCBs made by OSHpark or someplace so if you want top make on you would just have to buy the components. If there is a really enough interest I might think about putting together 10-20 kits of the PCBs, components and 3d printed case so you can solder it together.
  3. Thanks guys. I did not see a bus pass-through on the CI-7. I did get a PC-324 printer in the mail yesterday though and noticed it has a pass-through so you can daisy chain peripherals. Speaking of the PC-342, what type of thermal paper does it take. As I recall there are a few main types and the wrong stuff can ruin a print head.
  4. Here is a video on the completed interface. There is a link in the description to the design files and BOM on GitHub. The attached picture shows my test set up, the little blue box is the adapter.
  5. Yeah, getting into CNC milling is not cheap, but it is fun I have to do one more board version. When I prototyped the circuit on the breadboard I was just using a single 5V source and when I laid out the PCB I forgot to pull the MOSFET up to the 6V rail, not the 5V. That was an easy fix on the current PCB though. I had some strange troubles where it would work then not and I had some conflicting readings at times. I finally realized there was some smoltz between traces, it was too small to see but it was pulling down the PN2222 output that switches the MOSFET.
  6. I use a Taig CNC mill with my own stepper control box and Mach 3 (or Mach 4). I started using a Taig machine about 10 years ago at work on a research project and was so impressed I wound up starting a company on the side to sell them. (That first Taig is still being used every day to making everything from PCBs to microwave waveguides.) Having all the holes drilled and the board routed to shape is also a big bonus in my book If you want to check out my website (as long as it is OK to toot my own horn here) it is Soigeneris.com . I have some OLD videos on YouTube under my Soigeneris account. (My new videos about hobby stuff including this are under Jeffrey Birt, I know clever name for a YouTube channel )
  7. I milled out the 'final' PCB today. The top side looks a bit messy as I did a crude 'rub out' tool path to get all the copper out between the fingers on the card edge connector. On the bottom side I did a ground 'pour' so the rub out removed mostly just the copper between the fingers on the card edge. Since it is 'mechanically etched' the holes are not plated through so the handful of vias have to have wired passed through and soldered to both sides (this also limits you to no having vias under components.) I'll get it built up and tested later this week. Luckily I found a 6V wall wart power supply in my junk box I can use.
  8. Thanks! I just tried my Ozark-Engineered Commodore C2N to TI-95 adapter and it does work just fine. I can save and load programs to cassette. Of course it requires two bench power supplies and a few meters of cables to make it work I confirmed that: Pin3 (D0) is the input signal from the cassette adapter Pin5 (D2) is the remote control to turn cassette motor on/off ​Pin6 (D3) is the output signal to the cassette adapter All data lines float high (5V). The remote control line, Pin5 (D2), floats high and goes low to turn off power to the cassette motor. Having it float high provides power to position the tape. The TI-95 gives you a prompt to position the tape, you click on OK after it is positioned and then it will pull Pin5 (D2) low and prompt the user to press Play. You press play on the cassette deck and then click OK which will bring Pin5 (D2) back high and power the cassette motor. ​I don't have the cassette motor remote controlled yet. I did get a box from Mouser today which has a few different logic level mosfets to try out. I forgot to order a LDO 5V regulator so it will be another week or so before I have a completed adapter board. I also picked up a few different types of 10pin connectors to try for use on the TI-95/TI-74 expansion connector.
  9. I did just find and look at the PCIF manual: https://computerarchive.org/files/mirror/ftp.whtech.com/hexbus_cc40_ti74/PC%20Interface%20(PCIF)%20manual.pdf. It has a section on using PCIF with the TI-95 and includes a program listing for saving/loading programs over PCIF. Great, now I need to get an old DOS machine running and build a PCIF interface...
  10. Thanks, it would be interesting to know what it might do. I understand not wanting to open your new CI-7, no worries. Maybe acadeil can take some more photos of all around the board which might be sufficient.
  11. I'm working with a TI-95 Procalc right now and I don't think it will work, out of the box, with the PCIF. The TI-95 programming manual eludes to the fact that you can run machine code from a RAM cartridge but makes no mention of how to create said code. Trying to do something like that through the key-stoke programming would be painful I think. ​If anyone want to sell or loan a CI-7 I would like to get my hands on one for a while just to sketch out the circuitry. There is just no information about it out there, the pictures on this post are the best I found but the components are too densely packed on the top to see the traces or read component values from the picture.
  12. Since the CI-7 is unobtainium and I don't have access to one to reverse engineer I took a different route. I dug out a Commodore C2N Datasette and milled out an adapter PCB (card edge) to plug into the original connector. I've done some testing to characterize the current draw on the C2N which requires 6V for the motor and 5V for the logic. I have a few different PChannel mosfets on the way to try for automatically controlling the power to the motor (the C2N is high side switched.) I have not found any reference as to which data line is the cassette remote trigger but it should be easy to figure out. In my application the TI-95 has a 6VDC input on the expansion connector so the calculator can be powered by the same external power source that is used for motor power. Darn, I just remembered I forgot to order a LDO 5V regulator for the 5V supply to the C2N... Hopefully this weekend I'll have time to test it out on my TI-95 Procalc.
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