TI CC-40

From: Jim Battle <frustum_at_pacbell.net>
Date: Sun Feb 18 01:19:34 2001

Cameron Kaiser wrote:

>>I saw that "Hex-Bus" interface in the back. I haven't really gone through
>>the manual yet, but I did some web searching for a pinout or description
>>and can't really find any except for mentions of TI's apocryphal interfaces
>>and software. Hooking it up to my C64 would be cool if I could somehow turn
>>it into a regular DB-25 or equivalent and plug it in the C64's user port.

There is one really great source of technical information on the CC40 and
its very close younger brother, the TI-74. Unfortunately, the scanned
images are in a "Visioneer Paper Port" format. The free viewer is online
at the same site, but it is too bad they aren't PDFs.

I believe the following link is the right one, although it isn't responding
right now. I hope it is just temporarily down and not gone.

If it is away for good, I sucked down a lot of the files anyway, so if you
want hard-core info on the hexbus (and the closely related "dock bus" on
the TI-74), I can set it along to you. It is a nicely designed bus (for
its purpose, given the technology of the time).

The basic idea is this: a 4b data bus with two handshake signals. All
wires are driven open drain -- it is a true bus, not a point-to-point
repeater arrangement. It is an async bus, and different peripherals can
talk at differents speeds. The protocol is such that the transfer speed is
determined by the slower party in the transaction. Say there are two high
speed members and one slow one. The protocol speed will be slow if the
source or target is the slow device, but in the case of fast->fast, the
protocol is slow only until the point that the slow one realizes it isn't
being addressed, then the speed picks back up again. There are some
constraints on minimum and maximum handshake transitions (on the order of 8
microseconds minimum, a few milliseconds maximum), so it could easily all
be managed in software. The TI calculators are a combination of dedicated
bus controller and software interface.

The processor the CC40 and TI-74 (and 95) use is an interesting one; quite
different than many other 8b micros. Here is a link to a PDF describing
the whole family of chips. The PDF is quite massive, and most of it goes
into detail on configuring the myriad on-chip peripherals that exist on
various members of the family. Go to section 16, which starts on page 485,
to get to the instruction set.


Here are some other links, in no particular order. Some are much more
informative than others.

   (although it says .BIN, it is a text file, and quite informative)
http://home.debitel.net/user/groener1/comp_011.htm#TI 74
http://home.inforamp.net/~crown/TI/ti.html#TI 74 BASICALC

Finally, here is another uP based on a lot of the same technology as the
CC40 and the TI-74:

If you have any other good URL's you've found, please pass them on.

Jim Battle == frustum_at_pacbell.net
Received on Sun Feb 18 2001 - 01:19:34 GMT

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