Path: utzoo!utgpu!attcan!uunet!dasys1!eravin
From: eravin@dasys1.UUCP (Ed Ravin)
Newsgroups: comp.sys.cbm
Subject: Bursting C64 (WAS: Simultaneous disk & RS-232 access)
Summary: why external cia?
Message-ID: <8611@dasys1.UUCP>
Date: 6 Feb 89 16:41:05 GMT
References: <738@csd4.milw.wisc.edu> <7023@killer.DALLAS.TX.US>
Reply-To: eravin@dasys1.UUCP (Ed Ravin)
Organization: Committee of Commodore Interested Telecommunications Typists
Lines: 25

In article <7023@killer.DALLAS.TX.US> elg@killer.DALLAS.TX.US (Eric Green) writes:

>     Of course, hardware burst mode isn't cheap... I once estimated
>that it would cost at least $100 for a company to make money off the
>easiest-to-install setup (external CIA, buffers, & bank-switching ROM,
>with only two jumpers into the internals of your computer).

Hmmm.  Now I really should go home and read my 128 PRG again before putting
my electronic foot in my mouth, but the 128 doesn't have an external CIA or
any extra hardware for burst mode, does it?  The difference, as I remember
it, was that SP and CNT from each CIA (or maybe only one of them?) are
hooked into the serial bus.  Now, those pins are available on the user
port, so why couldn't you do a kludgy (but that goes without saying since
we're in Commie-land, doesn't it?) cable hack to get the hardware
functionality and then an even more kludgy software hack to get burst mode
to work?  At the very worst you might want a 4066 or some such silicon
switch to turn the hardware hack off so that you could use the normal
serial bus routines, which means you'd have to steal one of the i/o pins on
the user port to toggle the switch.

-- 
Ed Ravin                  | cucard!dasys1!eravin | "A mind is a terrible thing
(BigElectricCatPublicUNIX)| eravin@dasys1.UUCP   | to waste-- boycott TV!"
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