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The Compact Computer 40 (CC40)


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So, I determined that PC-IF TI 74 BASICALC BASIC tokenizer (tic74.exe) from the TIIF ZIP file (Peter Engels) will recompile ASCII files into BASIC programs for the cc40 (at least, it seems to work). Had to find a Win32 VM to run it in, since it's a DOS util.

 

So, I copied a bunch of the ASCII listings out of:

 

http://ftp.whtech.com/hexbus_cc40_ti74/cc40%20ti74%20hexbus.txt

 

and converted them to PGM files, which run on the cc40.

 

I also implemented rudimentary support for LISTing programs. Evidently, the cc40 will output the data as 1 line per command, but does not add CRLF (makes some sense, as you might want to skip LF if sending listing to a modem or something like that), so I put in some special code for that at the moment.

 

Jim

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Hi Jim,

I just opened up my Hexbus Modem HX-3100

I checked the distance between pin #1 to pin #1

On the 2 external Hexbus connectors. The distance

Is 11/16 of an inch or just under 3/4 of inch.

About external video, the original plan from

Texas instruments was a Hexbus adapter for the cc-40

Hooked to a TV. Michael Becker did build 2 such

Adapters, he made one for Charles Good , down in

Lima Ohio. It is a color version of Texas instruments

Original black and white proto type.

I would be very interested in getting a schematic

Of that version. The problem with the proto type

Is Texas instrument used PAL chips in the design.

Very easy to find, but impossible to program the

PAL chip without special equipment.

If I remember Michael Becker did find a work around

The PAL chip, using logics reader and standard

74ls chips

Hope this helps

Lee

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Hi Jim,

I just opened up my Hexbus Modem HX-3100

I checked the distance between pin #1 to pin #1

On the 2 external Hexbus connectors. The distance

Is 11/16 of an inch or just under 3/4 of inch.

About external video, the original plan from

Texas instruments was a Hexbus adapter for the cc-40

Hooked to a TV. Michael Becker did build 2 such

Adapters, he made one for Charles Good , down in

Lima Ohio. It is a color version of Texas instruments

Original black and white proto type.

I would be very interested in getting a schematic

Of that version. The problem with the proto type

Is Texas instrument used PAL chips in the design.

Very easy to find, but impossible to program the

PAL chip without special equipment.

If I remember Michael Becker did find a work around

The PAL chip, using logics reader and standard

74ls chips

Hope this helps

Lee

Thanks for the data. I'll add that to the library.

 

Looking at the spec, the interface is pretty easy, and I can program PAL chips here no problem.

 

Did the prototype use an TMS9918?

 

I'm just wondering what the target display should be. Composite 40 columns is pretty easy, but most people no longer have comp monitors to display. Is VGA or HDMI better now?

 

JIm

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Pics would be nice, and measurements, at least where they differ from the previous ROM cart measurements. If you could meter out some of the wires under the ICs, that helps as well. I am assuming it is a simple ROM=like layout, with the R/W line connected, but could be wrong.

 

Jim

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Pics would be nice, and measurements, at least where they differ from the previous ROM cart measurements. If you could meter out some of the wires under the ICs, that helps as well. I am assuming it is a simple ROM=like layout, with the R/W line connected, but could be wrong.

 

Jim

Here’s a good starting point for the 32K SRAM. When I can get some time, I can meter whatever you need.

 

c72c63cf6bb13a48751068caec0abe6d.jpgecccf57daaec4f50453fd8fe46d5e8c4.jpg6eed481904e7582e31d61870e053c0e3.jpgc301821a8f4df3ecedaf89124f83f544.jpg0288a4b47281a45af204f250dd83d3cb.jpg720e3348c939187ab83d57d3b41f3761.jpgbaff6df9dfcb7e940d2d8c7732399056.jpg

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OK, got a pretty good handle on the RAM cart, but here are a few questions:

 

  • Looks like 4 more passives under the batt. Can you tell what they are?
    • One looks to be missing (closest to RAM)
    • Looks like 1 is a resistor to hold !WE to Batt V when floating (next closest)
    • Looks like another holds !OE high for same reason (next farther away)
    • One looks to be left out (farthest away)
  • What pins do the resistor connect to?
  • It looks like someone reworked this unit to accept the Hitachi part. Thoughts?
  • Maybe if you can shine a strong light from the front and take a pic of the back, to maybe get some of the traces under the IC and the batt to show?

 

I'll go ahead and start a design.

 

Jim

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OK, got a pretty good handle on the RAM cart, but here are a few questions:

 

  • Looks like 4 more passives under the batt. Can you tell what they are?
    • One looks to be missing (closest to RAM)
    • Looks like 1 is a resistor to hold !WE to Batt V when floating (next closest)
    • Looks like another holds !OE high for same reason (next farther away)
    • One looks to be left out (farthest away)
  • What pins do the resistor connect to?
  • It looks like someone reworked this unit to accept the Hitachi part. Thoughts?
  • Maybe if you can shine a strong light from the front and take a pic of the back, to maybe get some of the traces under the IC and the batt to show?

 

I'll go ahead and start a design.

 

Jim

 

Yes, the cartridge was likely an 8K or 16K constant memory cart that was adapted into a 32K memory cart. Besides the two wires, there appears to be a couple cut traces. There are two diodes and three resistors on the board.

 

I'll create a pinout to the best of my ability including all the parts when I get back downstairs tomorrow. I'll unsolder the battery and peel it up and take some pictures for you.

 

With regards to the pinout for the actual cartridge, when I meter it, what do you want me to start as for pin #1 - the top left (the one closest to the front of the cart near the IC?) How about pin #21?

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Yes, the cartridge was likely an 8K or 16K constant memory cart that was adapted into a 32K memory cart. Besides the two wires, there appears to be a couple cut traces. There are two diodes and three resistors on the board.

 

I'll create a pinout to the best of my ability including all the parts when I get back downstairs tomorrow. I'll unsolder the battery and peel it up and take some pictures for you.

 

With regards to the pinout for the actual cartridge, when I meter it, what do you want me to start as for pin #1 - the top left (the one closest to the front of the cart near the IC?) How about pin #21?

 

Thanks.

 

The signals with boxes I do not need, or you can just check them. Grab this .PDN file and open in Paint.Net (free):

 

http://www.go4retro.com/downloads/CC40Flash/32kB%20RAM.pdn

 

You can turn on or off the top layer and determine some of the traces.

 

See a static pic of the work below

post-29128-0-99219400-1509332494_thumb.png

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Hi Jim,

Sure, depending on cost per board. I am interested , 1 or maybe 5 boards

This idea for a hookup board ,would make protyping

A lot easier for the CC-40. I remember we did a group buy on the

First HDX project as well as a group buy on the USB 99/4a project.

,

Just let me know cost, I can send you payment, I.e PayPal if you

Have a account.

,

Also , I would be interested in buying several of the thru hole

Prototype boards for this Hexbus project, help defray your cost

, if that is possible.

Thanks TI998owner Lee

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Can't do any more on any projects tonight, waiting for parts or info :-)

 

  • It looks like I've maxed out of RAM on the ATMEGA168. ATMEGA328s are due here tomorrow from Digikey, and they have 2KB RAM, so going to wait until then to add more functionality
  • Laying out a combo RAM/ROM cart, but realized I need to ask the placement and dimensions of the middle hole in the PCB. specs would be appreciated.

I'll try to put a board order in tomorrow night.

 

Jim

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Concerning HEXTIr, the current design runs the HEX BUS at 5V, so no issues there. SD card is level translated correctly using a voltage divider resistor network. (https://learn.sparkfun.com/tutorials/voltage-dividers)

 

Concerning the cart, the current ROM cart uses a 5V part, so no worries there.

 

I agree with the article writer, though, simple current limiting resistors are not a reasonable way to handle voltage mismatch.

 

Jim

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Jim, would you be considering creating other peripherals for the CC40 as well, such as the Hexbus video adapter? I can imagine every CC40 owner wanting one.

I am happy to create any amount of peripherals, provided there is demand and folks can decide just what they want.

 

RS232 is trivial, and I can whip that one up immediately using the same HW

 

Printer would be best implemented as a simple printer interface (like is on the rs232 interface)

 

Video Display suggests some questions:

 

  • Output to composite? VGA? HDMI? internal LCD?
  • Use actual period correct video IC, or something newer?

 

Jim

 

Not sure I would be interested in creating a real disk drive version, or a wafertape version. Plotter? What else?

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