Re: How much speed increase?: serial to parallel

[pubpc1@library.ucla.edu]

wily@svpal.svpal.org (Paul Creager) 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?

Quite a bit.  As Vitesse or Seven Hills will tell you, a serial
link at 19200 is the bottleneck in their printer driver packages,
not processing speed.  With newer DeskJet printers, which are
parallel only, you must use a serial to parallel converter, which
typically max out at 19200.

However, your DJ is an older model, with both parallel and serial
ports.  Maybe it can support the 57kbps speeds that the DeskWriter
models can.  If that is the case, you just need to install a high
speed serial port driver to use these.  I think Vitesse and 7H both
supply these and Sequential Systems seems to have one too that's
freely available on FTP sites.

At 57kbps, data is moving probably as fast as an unaccelerated GS
can generate, so you won't need a parallel card.  Faster GS machines
are a different story.

>
>Since parallel is moving 7-8 bits at a time, rather than 1 like serial, I
>can't expect a 7-8x speed increase, can I?

For the actual transfer, yes.  You have to account for the
time that the computer pauses to generate the image, though.

>
>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.).

At 57kbps serial or with a parallel card, the buffer will help.

-Scott G.