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TI-74 and cassette capabilities


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#26 acadiel ONLINE  

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Posted Wed Feb 7, 2018 3:13 PM

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Inside the cartridge.  Note, it's 256K total.  The address space for this unit was only 32K for the cart port.  There has to be some banking scheme going on here to support all 256K.  Also, note a power connector is on the board.

 

Note, the last vendor to sell accessories, High-Tech Solutions, dropped their website a long time ago.  Here's a historical list of what they sold as far as accessories:  http://web.archive.o...Accessories.htm



#27 acadiel ONLINE  

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Posted Thu Feb 15, 2018 5:28 PM

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46 components on this CI-7 cassette cable:

17 resistors
14 capacitors
4 inductors (blue)
5 transistors
4 diodes
1 CA358E RCA601 8 pin IC
1 74HC367E logic chip

Plus the cable, 10 pin connector, etc.

I’m willing to help board this out! Ksarul or Brain, have any time? :-)

#28 Jeff_Birt OFFLINE  

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Posted Wed Oct 3, 2018 6:46 AM

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.



#29 apersson850 OFFLINE  

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Posted Wed Oct 3, 2018 5:11 PM

Ah, I found it. So now I'm not just an owner of the unobtainium, the CI-7, but I also know where it is!



#30 Vorticon ONLINE  

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Posted Wed Oct 3, 2018 9:15 PM

I have one too new in box as a matter of fact :) I always found the PCIF to be more practical for file storage and transfers on the TI74 however.

#31 Jeff_Birt OFFLINE  

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Posted Thu Oct 4, 2018 6:36 AM

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.



#32 Vorticon ONLINE  

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Posted Thu Oct 4, 2018 8:05 AM

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.

 

I have never tried using the PCIF with the TI-95. When I have a few moments I'll have to check and see. It might be possible at a minimum to LIST to the PCIF.



#33 Jeff_Birt OFFLINE  

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Posted Thu Oct 4, 2018 9:03 AM

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.



#34 Jeff_Birt OFFLINE  

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Posted Thu Oct 4, 2018 9:12 AM

I did just find and look at the PCIF manual: https://computerarch...CIF) manual.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...



#35 Vorticon ONLINE  

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Posted Thu Oct 4, 2018 10:09 AM

I did just find and look at the PCIF manual: https://computerarch...CIF) manual.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...

I believe there is a schematic out there for a replacemnent interface. And no need for an old DOS PC. There is a modern update to the transfer software here: http://pengels.bplac.../index.php/tiif

#36 Vorticon ONLINE  

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Posted Thu Oct 4, 2018 10:13 AM

And here's the schematic link: ftp://ftp.whtech.com/hexbus_cc40_ti74/PC_Interface.png

#37 acadiel ONLINE  

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Posted Thu Oct 4, 2018 6:42 PM

Hey there! Got your email, but have been so busy, I haven’t responded yet. I’ll take a whole bunch of high res pictures and put them on Dropbox this weekend.

#38 Jeff_Birt OFFLINE  

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Posted Fri Oct 5, 2018 5:47 PM

Hey there! Got your email, but have been so busy, I haven’t responded yet. I’ll take a whole bunch of high res pictures and put them on Dropbox this weekend.

 

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.

Attached Files



#39 OLD CS1 OFFLINE  

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Posted Fri Oct 5, 2018 6:16 PM

Neat!






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