Re: How much speed increase?: serial to parallel

[dempson@actrix.gen.nz (David Empson)]

Paul Creager <wily@svpal.svpal.org> wrote:

> I finally freed up some slot space in my GS, and I'm debating getting a
> parallel card for my HP DJ550C.  How much of a speed increase should I
> expect compared to my 19200 serial connection?

It depends how fast the software is able to provide data to the parallel
card, and how fast the printer accepts it.

A 19200 bps serial connection has a maximum transfer speed of 1920 bytes
per second.  I'd expect typical transfer speeds of 10,000 bytes per
second from a parallel card (about five times faster than your serial
connection), assuming the software is providing data quickly to the card
(this will depend on the driver).

The other question is how much data the printer is able to buffer.  If
it only has a small buffer, you might not notice much difference.
 
> Furthermore, any practical benefit to installing buffer RAM in my 550C?
> It can take two 256K modules for a total of 512K.  I print simple text
> stuff from P8 (ProTERM), and of course use the GS side for the fancy
> stuff (Pointless, etc.).

The buffer will only be useful if the computer can send data to the
printer faster than the printer can print the page.  This is more likely
for text-based printing, but that won't need much buffer space anyway.

I wouldn't expect the buffer to make any difference when printing from
IIgs desktop programs unless you have a fast accelerator in the machine
_and_ you are using a parallel card.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand