Date   : Mon, 15 Jun 1992 17:01:46 GMT
From   : wieland@ea.ecn.purdue.edu (Jeffrey J Wieland)
Subject: Re: Kaypro Liquidation

In article <samw.708453586@bucket> samw@bucket.rain.com (Sam Warden) writes:
>Re: interrupt-driven Kaypros.
> 
>Kermit on my K10 does 19k through the tty port (serial printer port)
>without any machine-dependent configuration.  I had assumed it must
>be polling.  Impossible?  Pretty impressive, anyway.
>-- 
> 
>samw@bucket.rain.com (Sam Warden) -- and not a mere Device.

This is true -- CP/M Kaypros have no difficulty performing file
transfers at high baud rates by merely polling the serial port.
The problem comes with terminal emulation.  The '84 series Kaypros
are notoriously slow for things like clearing the screen, scrolling,
etc.  At 2400 bps, they will drop something like 30 or 40 characters 
after a clear screen command is issued!  

The '83 series machines are much faster at this stuff.  They use 
memory-mapped video -- the video RAM is bank switched in whenever 
the ROM is switched in.  I believe that the VRAM is located at 0x2000 
when it is switched in.

The '84 series (and all of the Kaypro 10s, I believe) use a 6845 or
6545 video controller chip, and the video RAM is only accessable
through that chip.  Its a lot slower, but you get all of those nice
video attributes, plus the 160 X 100 block graphics.  The only way
I know of for a '84 series machine to be a usable terminal is with
interrupts.  Heck, with Kermit-80 they'll drop 1 or 2 characters after
a screen clear at only 300 baud (using polled IO, of course)!  File
transfers are just fine, though.

--
                           Jeffrey J. Wieland
                     Communication Systems Programmer
                       Agricultural Computer Network

    INTERNET: wieland@acn.purdue.edu           ENTM 216
    BITNET:   WIELAND@PURCCVM                  Purdue University
    UUCP:     ...!ecn-ee!wieland               West Lafayette, IN 47907
    FAX:      (317)494-8342                    (317)494-8333