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The Compact Computer 40 (CC40)


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Now that the boards are not such a mystery, I'd like to fit the little "tabs" from the original PCBs onto the RAM and ROM boards. If someone (Joe? :-) or Lee could micrometer them out, that would be appreciated.

 

I also need to throw the entire set of design online, as all of my projects are open source. I hesitate only because I am not sure if I want to put up 3 separate projects in github, or 1 with all three designs.

 

Jim

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Hey Jim -

 

I got the two RAM carts working great. One ROM cart is working, and other is locking up the CC-40 when I put it in and then power it on. Tried multiple EPROMs. Cart does not lock up the unit with the ROM removed. Tried re-flowing all solder joints, so will likely have to go down the path of figuring out what's not conducting. Put under my magnified lighted loupe and I don't see any shorts or anything.

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Hey Jim -

 

I got the two RAM carts working great. One ROM cart is working, and other is locking up the CC-40 when I put it in and then power it on. Tried multiple EPROMs. Cart does not lock up the unit with the ROM removed. Tried re-flowing all solder joints, so will likely have to go down the path of figuring out what's not conducting. Put under my magnified lighted loupe and I don't see any shorts or anything.

ROM cart is pretty simple, so it sounds like an address or data line not making connection (maybe the socket itself)

 

Jim

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ROM cart is pretty simple, so it sounds like an address or data line not making connection (maybe the socket itself)

 

Jim

 

Found it. There was a non-connection by the breakaway at the very top of the cart where R2 connected to R1 on the common side that wasn't conducting. I jumpered it between the two resistors on the bottom and now have conductivity all the way to R5.

 

I'm wondering if when I broke them apart I did something with the trace right there.

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Hi Jim,

OK, I did some measures for the little ( 4 ) tabs on the

CC-40 ROM boards. Using several CC-40 Memo processor boards

As examples to check with.

,

Looking at the board with the chip side up and the cart edge

Connector facing you. The distance from the top edge to the

First tab is 6/32 inch. ( left hand side of cart )

The tabs are slopped, so this measure

Is to the beginning of the slop. The tab measures ( top of tab )

3/32 of inch across, base of tab is 4/32 of an inch. Small slop

From top edge to bottom edge, on the tab. Same for each tab.

,

The distance between the top tab and the bottom tab, ( Measure between

Edge of base of the top and bottom tab) is 3/4 of inch.

,

You can use the same measure on the right hand side of the cart as well.

The left and right side of the cart measure the same.

I checked several CC-40 carts they all are the same.

,

The only difference I could find on other Texas Instruments produced

CC-40 carts was some are missing the top left hand side tab. But

This could of been a quality control issue, does not seem to

Be an issue for the cart case, fitting the carts.

,

Hope this helps

Lee

TI998owner

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Hi Jon,

The tabs on the original CC-40 carts are for

Cart alignment when placed in the plastic cart case.

The tab , you see on the first batch of ROM and Ram

And proto boards from Jim are the break away that held

The 3 boards together. Not what we were measuring

For the production version or possible the next batch

Of boards.

,

Lee TI998owner

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Hi Jim,

OK, I did some measures for the little ( 4 ) tabs on the

CC-40 ROM boards. Using several CC-40 Memo processor boards

As examples to check with.

,

Looking at the board with the chip side up and the cart edge

Connector facing you. The distance from the top edge to the

First tab is 6/32 inch. ( left hand side of cart )

The tabs are slopped, so this measure

Is to the beginning of the slop. The tab measures ( top of tab )

3/32 of inch across, base of tab is 4/32 of an inch. Small slop

From top edge to bottom edge, on the tab. Same for each tab.

,

The distance between the top tab and the bottom tab, ( Measure between

Edge of base of the top and bottom tab) is 3/4 of inch.

,

You can use the same measure on the right hand side of the cart as well.

The left and right side of the cart measure the same.

I checked several CC-40 carts they all are the same.

,

The only difference I could find on other Texas Instruments produced

CC-40 carts was some are missing the top left hand side tab. But

This could of been a quality control issue, does not seem to

Be an issue for the cart case, fitting the carts.

,

Hope this helps

Lee

TI998owner

 

OK, from top of board:

 

0" top of board

6/32" from there to top most wide portion of top tab

4/32" from there to bottom of wide portion of top tab

24/32" from there to top most wide portion of bottom tab

4/32" from there to bottom of wide portion of bottom tab

 

And:

thinnest portion of tab is 3/32, meaning the slop is 1/64" for each side

 

I laid them out, but they seem off compared to Jon's images, where the bottom tab look like it is also 6/32" from the bottom of the PCB. Maybe I misunderstood your measurements.

 

I also don't see a measurement of the width of the tab (the part that sticks out). I used .025", but I doubt that is right.

 

Here is a pic of what I have so far:

post-29128-0-32544600-1512967341_thumb.png

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Hi Jim,

The width of each tab , the part that sticks out from

The board is 1/32 inch. The measure of 6/32 from bottom.

Of the cart to the base of the tab is correct.

The picture is off, because the measure would be

Rather squared , or even looking. Same distance for the top tabs

And bottom tabs from top edge of cart as bottom edge of cart.

 

,Lee TI998owner

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OK, I fixed the width to .03125 (1/32")

 

I guess I need to get the length of teh main part of the PCB. If I exclude the edge connector, the height of the PCB is 1.55"

 

If I figure the two tabs at 4/32", the distance from edge to tab as 6/32", and the distance from the tabs to each other is 24/32", that's:

 

6/32 + 4/32 + 24/32 + 4/32 + 6/32 = 44/32 = 1.375", not 1.55" That probably explains the difference. I used helocast's data for the PCB size minus the edge connector.

 

Better data on the main PCB height would help.

 

Jim

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OK, I fixed the width to .03125 (1/32")

 

I guess I need to get the length of teh main part of the PCB. If I exclude the edge connector, the height of the PCB is 1.55"

 

If I figure the two tabs at 4/32", the distance from edge to tab as 6/32", and the distance from the tabs to each other is 24/32", that's:

 

6/32 + 4/32 + 24/32 + 4/32 + 6/32 = 44/32 = 1.375", not 1.55" That probably explains the difference. I used helocast's data for the PCB size minus the edge connector.

 

Better data on the main PCB height would help.

 

Jim

Can you please make these tabs breakaways or otherwise optional? Reason that I’m asking is because I tried making a 3D print with them, and it’s a pain to file the filler out of those four, and the board itself fits fine in mine without the tabs. Thoughts?

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Hi Jim,

OK, I just got home from work.

,

Using the standard ruler. The height of the Cart, ( top edge to bottom

Of cart at the edge connector is 61/32 or 3/32 short of 2 Inch total.

,

The main board is 1 inch and 15/32 or 47/32 or 1 inch and half inch minus 1/32

,

From the main board edge to the cart edge connector is 14/32 or 2/32 short of 1/2 inch.

,

Adding these all together 47/32 + 14/32 = 61/32 or 3/32 short of 2 inch total height.

,

Also using this 47/32, measure from the top edge of the cart to the center of

The first tabs , = 9/32 , measure from center of first tab to center of second

Tab , = 29/32 , then measure from center of second tab to bottom edge of

Main part of cart , = 9/32. Add them up 9/32 + 29/32 + 9/32 = 47/32

And if we add in the edge connector part 14/32 we end up with 61/32

Or 3/32 short of 2 inch's.

,

Again I hope this is useful

Lee TI998owner

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Jim and Jon,

 

Once the revised boards come in, if neither of you have any objection, I would be willing to supply the MegaMod EPROMs and/or Flash chips for a nominal fee for those who don't have the facility to burn their own from the file. I am thinking about $5 for the 39SF040 and $6 for the 27C040 which would include shipping via USPS First Class postage.

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Can you please make these tabs breakaways or otherwise optional? Reason that I’m asking is because I tried making a 3D print with them, and it’s a pain to file the filler out of those four, and the board itself fits fine in mine without the tabs. Thoughts?

Can you puts some pics in? I'm not opposed to making these breakaways, but I am not sure why the 3D printer is having such a time making the channel. Do you have a stl file I can try here?

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