8-bitters and multi-whatever

M H Stein dm561 at torfree.net
Wed Sep 12 01:54:50 CDT 2007

From: Allison <ajp166 at bellatlantic.net>
Subject: Re: 8-bitters and multi-whatever

>CP/M or most other OSs for non 8080/z80 could easily be fooled into 
>redirecting disk IO to a serial port. Though CP/M was modular enough
>and most widespread it was most often hacked that way.  There is 
>however no rule that says a OS must talk to a disk as storage and once 
>that is clear then it's easy to cobble up a packet protocal that transmits
>the needed data across a serial or parallel port to a willing and enabled 
>host. Some systems like the big S100 crates or multibus running MPM used
>the bus and some common memory so that multiple CPUs typically z80 with 
>128k ram, rom and serial IO plus a bus interface and memory manangement 
>for off board memeory.  MPM would be the server and CP/M would be the 
>local cpus that users interacted with.  It wasn't seen often as it was
>expensive to ahve the hardware and the average hobbiest at the time 
>rarely had more than one fully functional system and maybe a SBC
>of the KIM-1, EVK68, AIM65 or SDK85 level.

Don't forget about external RS-232 Network hubs, like the NetCommanders et al;
I had 12 AIM65s and two Cromemcos at a factory site talking to each other back 
in those days.

Also, some of the PC local net software could use the parallel and ethernet 
ports as well as RS-232 and bridge among them for a peer-peer net, or a
client-server model using an external hub. 

Now there's a question, whether Interserver can handle multiple Interlink clients
(one at a time of course); anybody ever try it?


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