TRS-80 curiosity

Tony Duell ard.p850ug1 at
Wed Apr 12 14:38:00 CDT 2017

On Wed, Apr 12, 2017 at 8:15 PM, Fred Cisin via cctalk
<cctalk at> wrote:
>>>> of which I don't know.  It is a 40 pin to 50 pin ribbon cable with a
>>>> black box connecting them that is labeled TANDY.  I know of nothing
>>>> the Tandy made that used a 50 pin connector other than a hard disk.
> On Wed, 12 Apr 2017, Parent Allison via cctalk wrote:
>> Maybe...
>> The only device  I know of like that was trs80 to a printer (Centronics or
>> compatible ).
> Radio Shack used 34 pin for "Centronics" compatible printer cables.
> (#26-1401 was a cable with 34 pin card edge to 36 pin Blue Ribbon)

There was a 'cable' (containing a few TTL ICs) to link a Centronics
printer to a Model 1 CPU/keyboard unit without needing an expansion

It was in 2 parts. The short one included the logic and had a 40 pin edge
connector on a short length of ribbon cable connected to the box
containing the logic. The PCB in said box had a _40 way_ card edge coming
out through the side with a slot after 34 contacts. There was a longer cable
with a 40 way edge connector (with a polarising key after 34 contacts,
between the contacts) on one end and a 36 pin microribbon connector
(to go to the printer) on the other. You connected the long cable to the card
edge on the box of logic, plugged the short cable from that into the expansion
bus connector on the keyboard and plugged the other end of the long cable
into the printer (which had to supply the +5V needed for the logic in the

If you then bought an EI, you could connect the long cable (only) to the
34 pin card edge on the EI.

The only problem was that if you did this, you couldn''t fit the 'hood' over
the connector (as it was designed for a 34 pin connector). And the cable
didn't fit the M3 or M4.

I had one. In the end (after getting an EI and later a M3), I replaced
the connector
with a 34 pin one. It then didn't fit the original short cable/logic
(which I had no
use for), but did work with the EI and M3.


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