[Coco] Coco4?

[Gene Heskett]

On Saturday 16 November 2013 12:27:11 Mathieu Bouchard did opine:

> Le 2013-11-16 à 12:14:00, Bob Devries a écrit :
> > The SCII is a no-halt controller with an accessory bus into which can
> > be plugged the 4-in-1 card which has an RTC, a serial port, a
> > parallel port, and a SCSI port, all inside the one cartridge.
> 
> What's this 4-in-1 card and where does it come from ? The SCII I have
> has a RTC and a parallel port, but no serial and no SCSI.
> 
> Is the serial port using a UART ?
>
Yes, but its effectively wired tip-ring-ground, so you MUST used software 
XON/XOFF.

The RTC is subjected to powerup/pwerdown's trashing its time, and the 
parport is NOT buffered or handshake capable.  If you want to drive a 
parallel printer, you must build an interface that does this, sitting right 
on the port else the FCC's required noise filters in the printers port will 
make it skip characters or drop bits, screwing with the character.  Totally 
unusable with a CGP-220, CGP-115 or a DMP-132 on a coco 3, the slower 
clocked coco 1 & 2 will probably work 99.9% of the time.  The slower 
clocking of the 1 & 2's will bring up the data and hold it long enough for 
the printer to get it pretty, but not 100% reliably.

Cheers, Gene
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