[net.micro.cbm] Herky-jerky Cardco Graphics

joels@tektools.UUCP (Joel Swank) (03/14/85)

> > I also bought the Cardco +G interface.  Is everyone else who bought
> > one of these happy with it?

> I bought one of these, and I am very UNhappy with it.  I am using it with
> an Epson MX80, so my experience may not be applicable to the Gemini.
> Printing any kind of graphics takes *f*o*r*e*v*e*r* (that includes the
> Comodore special characters, anything that is not standard ASCII) because
> it does continuous forward-backward shuttling of the print head back and
> forth.  This beats the print mechanism to death, and takes about 45-50
> seconds for every single line of print.  


Don't blame the interface, I haven't found one that doesn't have this
problem. This is standard behavior in graphics mode with both the Epson and
Gemini printers. The problem could be cured in either the printer or
the interface. To print graphics the printer must receive an escape code
followed by a byte count followed by that number of dot columns of data.
For each such packet, the printer makes a pass with the head. I assume this
is because of acceleration and deceleration needs. When printing Commodore
graphics, the Cardco sends each character as a packet. This results in the
herky-jerky printing. This problem could be cured by either the printer or
the interface buffering graphics and only making a pass when needed. Of
course this requires a sizable chunk of RAM, which is probably why neither
the printer or the interface does it. Some of the newer Epson compatable 
printers do not have this problem. (Panasonic)

Joel Swank
Software Center Tools Support
50-487
Tektronix
Beaverton OR 97077
(503) 627-4403