Organization: The Black Box, PO Box 591822 Houston, TX 77259-1822
Date: Sun, 20 Dec 1992 22:02:34 GMT
Message-ID: <1992Dec20.220234.12687@blkbox>
References: <9212151234.AA10247@LL.MIT.EDU>
Lines: 245
sage@LL.MIT.EDU (Jay Sage) writes:
>Several attempts to reply directly to "reynaert@arizona.edu" have failed with
>a "user unknown" message from the host, so I will post my response here.
>>> I have benn having problems with my communications when I use an external
>>> modem at 2400 BPS, Some characters are lost while the comunication is
>>> going on. This only happens when there is output to my adm3a screen.
>>> Curiously, this doesn't happen at 1200 BPS or less. Also I have down
>>> loaded files at 2400 BPS and no data has been lost...
> This is a very well known problem with Kaypro computers. It is the
>result of a poor design of the video display. When a new line must be
>created at the bottom of the screen and the existing lines have to be
>scrolled up, the system takes so long that incoming characters are lost. I
>don't use a Kaypro myself, but many friends do. There is a file that
>implements a correction to this (I can't remember exactly what it does or
>how it does it). A common work around is to clear the screen every time it
>fills up and to start again from the top. If you don't get more specific
>advice from others who reply to you, get back to me and I will try to dig up
>that file for you. It is posted on my BBS system, which is sponsored by the
>former Kaypro User Group of the Boston Computer Society (now broadened to
>include all CP/M and MS-DOS computers). In case you are a BBSer, its phone
>number is 617-965-7046. This reaches first a v.32bis modem and, if that one
>is busy, a USR Courier HST on line 2 (alternatively reachable directly at
>617-965-7785).
>-- Jay Sage
Jay, this is not totally correct. I ran a USRobotics HST/V32/V42bis on my
Kaypro 10 for several years, at 19200 baud, without problem. I DID have to
rewrite the overlay for BYE and Ybbat to do this though, as they were incorrectly handling the Z80-SIO fifo. The SIO has a 4 character incomming FIFO, and it
will allow you to do 19,200 (or maybe even 38400) without a hitch if you
implement a queue, and every time you go to get a character off the SIO, insteadget the chars off the SIO, and put them in the queue, and then return the top
char off the queue. I am going to include ybh-kay1.asm which implements this
at the end of this message.
Please note, most modem overlays such as bye, mex and others did not implement
this. Hope you can use it and hope it helps. BTW, the queue I used is 256
chars, if you need a bigger one (long interrupts blocking the sio for example
during a disk read) then you will need to enlarge it.
