[Coco] Re: Coco printer primer...

[Alex Evans]

On Feb 15, 2006, at 12:58 PM, Torsten Dittel wrote:

>> I have access to an Okidata 320T (OS compatible down to MS DOS,  
>> and emulates IBM ProPrinter III, Epson Fx-80, ANSI and Oki  
>> Microline) with a RS-232C serial adapter that works great. Would  
>> making a serial cable to work with the 'bit banger' port (do not  
>> have a RS-232c cart yet) be difficult? I know on a PC this  
>> wouldn't be a problem, but, using the four pins from the b/b port  
>> to a 25 pin sounds too easy of a solution...
>
> Well, the signal levels of RS-232 (logical "one" is between -12V and
> -3V, "zero" between +3V and +12V) are different from what's on the
> bitbanger port (0V or 5V). Normally you'd need a small circuit with  
> it's
> own power supply which contains a MAX232 compatible IC which will  
> adapt
> the CoCo's levels to the standard. However, some printers might accept
> the CoCo's signals and I'm sure there's a workaround without too much
> hardware efforts. Another question is if you have real CTS/RTS  
> hardware
> handshake or XON/XOFF protocol software handshake.

The bitbanger port is supposed to be RS-232 compatible, and I have  
never seen a piece of equipment which had problems related to  
anything other than the available data rates, or lack of hand-shaking  
signals.