S/360 channel (was: Anybody live in Chile?)

[Lawrence Wilkinson]

On Sat, 2005-09-03 at 04:31 -0400, Tim Shoppa wrote:
> William Donzelli wrote:
> > [on the subject of bus and tag electrical interface]
> > The drivers and receivers might be a little bit of a hassle,
> > unless some were chopped out of an existing IBM.
> 
> My recollection, based on mid-70's TI databooks, is that the interface
> chips being sold for bus and tag are very similar to TTL open-collector
> drivers and stock TTL receivers (Schmitt triggers if you want).
> 
> I will go look at the books and check again to see if it really is that
> simple :-).
> 
> Tim.
When I made up a channel adapter (that is, to connect to a CPU) I used
TTL (probably LSTTL), with 374 Tristate Tx and 244 Rx.  This worked, but
maybe didn't meet the official spec.

I think you can find a spec on Bitsavers, A22-6843-3.  This gives >2.25V
for 1 and <0.15V for 0.

>From a higher-level perspective, the channel is not unlike SCSI. Making
a channel which would work with a specific I/O device wouldn't be too
difficult.  I only ever implemented a multiplexor (byte-at-a-time)
device for which the throughput requirements were not too severe.
-- 
Lawrence Wilkinson                                 lawrence at ljw.me.uk
The IBM 360/30 page                       http://www.ljw.me.uk/ibm360