Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!cmcl2!yale!sekora-jay
From: sekora-jay@CS.YALE.EDU (Jay Sekora)
Newsgroups: comp.sys.cbm
Subject: Re: Questions about 128 Reliability (Considering upgrade from C64)
Message-ID: <39729@yale-celray.yale.UUCP>
Date: 6 Oct 88 17:35:24 GMT
References: <205.234963B0@isishq.FIDONET.ORG>
Sender: root@yale.UUCP
Reply-To: sekora-jay@CS.YALE.EDU (Jay Sekora)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 16

In article <205.234963B0@isishq.FIDONET.ORG> Geoffrey.Welsh@isishq.FIDONET.ORG (Geoffrey Welsh) writes:
>> <deleted>
> 
>   While it is correct that only one CPU is operating at any given 
>
>instant, it should be noted that CP/M I/O is done by the Z80 switching 
>the 8502 in (i.e. I/O code is performed by the 8502 at the Z80's request).
> 
>   Geoff ( watmath!isishq!izot )
My understanding is that this was true of the CP/M add-on card for the C64,
but that on the 128 the Z80 does all it's own i/o and doesn't have to rely
on the 8502 for anything.  I haven't really done anything in CP/M on the ML
level, so I can't vouch for that.  (Incidentally, when you power up a 128 w/o
a ROM cartridge, the Z80 takes over first, and then cedes control to the 8502.
((I think.)) )
jay (sorry, I don't know my return path.)