[Coco] RS232 paks

[Darren A]

On 3/3/09, Mark McDougall wrote:
> Hi Guys,
>
> Was wondering if you could answer a few quick 232-related questions:
>
> 1. Which ACIA/UART chips are used in the various coco RS232 paks? Which
> one(s) is/are the most common? Which (if any) is considered "superior"?

The 6551 ACIA is used in every RS-232 pak that I have seen (Tandy
Deluxe, Direct Connect Modem, CoCo PRO!, Roger Taylor's wireless pak
and I think the TelePak).

> 2. Are any of the handshaking lines (RTS/CTS etc) used? If so, which?

The 6551 has RTS, CTS, DSR, DTR and DCD.  It doesn't implement them
very well IMO.  Some of these must be asserted in order for the ACIA
to be enabled for both transmit and receive.  If CTS goes HI while
transmitting, it will stop in the middle of a byte.  I'm not sure if
all of these are present on the connector.

Sock Master has some info on his site on how to improve the hardware
handshaking:
<http://www.axess.com/twilight/sock/cocofile/rs232mod.txt>

> 3. What sort of connector(s) is/are used on the more common 232 carts?

Mostly DB25.  The telepak may use a DB9.  The wireless pak has no connector.

> Also, pointers to the various manuals/schematics would be greatly
> appreciated!

This pdf has the Tandy Deluxe, DC Modem Pak and CoCoPRO! :
<ftp://maltedmedia.com/coco/MANUALS0/MISC/HARDWARE/CoCoPro_RS232.pdf>

Darren