3 Sep
2005
3 Sep
'05
5:11 a.m.
On Sat, 2005-09-03 at 04:31 -0400, Tim Shoppa wrote:
William Donzelli wrote:
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.
[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. 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