My experience is with hp terminals using enq-ack protocol. When you
send stuff to one of the "devices" (screen, printer port, mini-tape,
etc.) the keyboard gets locked for the duration of that transfer.
Usually, this is not very long. If the line is fast, you don't have
much time to do anything between transfers. The program I wrote used
binary transfers so we could dump raster graphics to the terminal
printer.
There are other ways to do it than the one I used but it requires a
tricky driver in the operating system. Old hp rte systems used to be
able to read/write to the mini-cartridge tape system in the 2645
terminal while you did something else on the screen. If you limit the
data to simple ascii print, you have a much better chance. If the stuff
you write is really short (less than 2k) then the time you can't type is
going to be pretty short.
vt terminals... I don't know. I have no idea how they handle the
keyboard when you dump stuff to the printer port.
The problem can be solved. You have to know a *LOT* about the terminal
you are going to use. There are always some tricks that you have to
learn that aren't in the manuals. (These days, there isn't much in
manuals anyway.)
jim lewis
______________________________ Reply Separator _________________________________
Subject: Re: Re[2]: Debian + PC with multi RS... port -> n x (text d
Author: [EMAIL PROTECTED] at ~AMSCCSSW
Date: 9/12/97 7:38 PM
On 12 Sep 1997, TENCC01.LEWIS01 wrote:
> It probably doesn't work the way you want. Usually the terminal keyboard is
> locked until the print is finished. Making the terminal useful for input at
the > same time is generally not possible. It would require a very clever
terminal > and an extremely clever driver. > > jim >
... Or just a larger RAM buffer in the printer and hopefully a fast line,
after all I don't think that in a POS system anyone would need to print
large reports at one of the terminals, most likely just a few lines on a
page for each sell or incoming materials. I would choose to connect a
printer to the port _on_the_main_computer for large reports. But it would
be interesting just to know more about that keybord lock during prints.
Nicola Bernardelli <[EMAIL PROTECTED]>
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