Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!umich!samsung!brutus.cs.uiuc.edu!apple!motcsd!motsj1!mcdchg!ddsw1!tronsbox!tron1
From: tron1@tronsbox.UUCP (HIM)
Newsgroups: comp.sys.amiga.tech
Subject: Re: A Cost Effective MULTI-SERIAL Device Proposition
Keywords: Multi-Serial Input Ouput Hardware Options Expansion
Message-ID: <25d4feb5:888.6comp.sys.amiga.tech;1@tronsbox.UUCP>
Date: 11 Feb 90 07:04:41 GMT
References: <76649@tut.cis.ohio-state.edu> <76779@tut.cis.ohio-state.edu>
Lines: 43

>----------
>  Resp: 4 of 5 by *Masked* at ncsuvm.ncsu.edu
>Author: [Brandon Hill]
>  Date: Thu Feb 08 1990 23:18 

>First, the game port cannot alone drive a serial connection, as it is not
>set up to sink or source the currents required for a serial connection.

This is >NOT< a major problem.

>The first problem is that there are no lines on the game ports that will
>trigger an interrupt in the cpu.  This means that if you wish to receive data,
>you will have to poll the receive line constantly.  You might be able to get
>by with simply polling at the bit rate (1200 times per sec at 1200 baud),
>but you would be much safer polling at twice the bit rate to take care of
>any switching transients.  This will result in quite a bit of software
>overhead which gets you nothing unless you are actually receiving or
>transmitting data.  I am not even sure that the amiga is capable, without
>external hardware, of interrupting exactly a certain number of times per
>second. (At least, the master int disable would reek major havoc on a software
>driven bit level protocol)

Hmm.. when I looked at the software (wich I am more than willing to do) I
was just going to do normal I/O through the gameport.device , this device
currently has support for independant and simultaneous reception of at least
5 signals (left, right , up, down, fire) -- this is enough for a serial
connection.

Now , you would NOT run that mode of the device but you see my point , I
think with the help of a 16550A (a UART with on board 15 character buffer)
you should be able to get 2400 baid easy using the stanadrd intuition I/O
library for that gameport -- forget the baud rate , let a clock on the
external hardware set/decode it .. (fixed rate with a toggle switch maybe??)

****************************************************************************
Everything I say is Copr.  1990, except the stuff I stole from someone else
and the stuff I don't want responsibility for.
 
Kenneth J. Jamieson: Xanadu Enterprises Inc. "Professional Amiga Software"
      UUCP: tron1@tronsbox.UUCP  BEST PATH ---> uunet!tronsbox!tron1 
      Sysop, Romantic Encounters BBS - (201)759-8450 / (201)759-8568 
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