Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!mailrus!tut.cis.ohio-state.edu!erd
From: erd@tut.cis.ohio-state.edu (Ethan R. Dicks)
Newsgroups: comp.sys.amiga.tech
Subject: Question about 8520 CIA chips
Message-ID: <11419@tut.cis.ohio-state.edu>
Date: 23 Apr 88 19:24:24 GMT
Organization: The Ohio State University Dept of Computer and Information Science
Lines: 30


I looked at the differences internally between the 6526 CIA and the 8520 CIA, 
and found that the only difference is in the TOD clock, one is BCD and the
other is binary.  I also found by looking in my AW RKM hardware manual that
the TODs are used for the timer.device for 60Hz and millisecond event timers

I assume that there is not a version of the 6526 which can be stuck directly
on the 7.1 MHz Amiga bus, but am I wrong?  Are the pinouts the same?  (I could
not find an 8520 pinout in _my_ literature, but then I don't have the A1000
schematics)  If you could stick a 6526 in the 8520 slot, how could you
replace the timer.device with one which understands a BCD timer?  Note:  I
am not asking how to manipulate BCD with a 68000, but how to change a device
driver which is _not_ disk resident.

The obvious benefit _IF_ such a swap is possible, is that for owners of A1000
(since we _can_ patch Kickstart) with blown 8520s, the wait for a replacement
8520 can be shortened by using the much more readily available 6526.  I do
realize that I am probable blowing smoke rings here, but I have to at least
pose the question, so it can be shot down completely and thouroghly.

(IMHO, followups should be posted to allow all parties interested to see all
the discussion)

Thanks,
-ethan

-- 
Ethan R. Dicks      | ######  This signifies that the poster is a member in
Specialized Software|   ##    good sitting of Inertia House: Bodies at rest.
2101 Iuka Ave.      |   ##
Columbus OH 43201   | ######  "You get it, you're closer."