Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!NCCIBM1.BITNET!GHK
From: GHK@NCCIBM1.BITNET
Newsgroups: comp.os.cpm
Subject: Re: INFO-CPM Digest V89 #142
Message-ID: <8906290704.AA24802@ucbvax.Berkeley.EDU>
Date: 28 Jun 89 20:05:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 27



> Date: 24 Jun 89 09:50:42 GMT
> From: pacbell!sactoh0!ianj@ames.arc.nasa.gov  (Ian R. Justman)
> Subject: Buffering with Softcard CP/M and Super Serial Card on Apple II
>
> I have a problem using some of my communications software on my
> Apple II Plus using Softcard CP/M and a Super Serial Card clone.  I
> keep losing characters like crazy.  Is there a way to buffer
> incoming characters so I don't miss a beat?  Thanks in advance.
>
  Due to the slow clock speeds of the 6502, which does all of the I/O
 for the PCPI APPLICARD, it is very capable of loosing characters.
 Functions such as ringing the bell or clearing the screen takes all
 of the 6502 and any further characters being recieved will be trashed
 until the current process is complete.  The only way to avoid this
 is to allow the board to generate a processor interupt and store the
 data in a buffer until there is time to do something with it.  This
 works well but you will probably have to write it yourself.  This is
 not an easy task without the PCPI developers kit.  The interupt must be
 written in 6502 native code and interfaced with the PCPI BIOS.  The
 developers kit has the tools needed for this process.  I wrote a versio
 for the Promethieus Versacard and was very succesful in getting it to
 work for speeds up to 19200 bps.

       Gary Hutchison
       GHK@NCCIBM1