🚀 go-pugleaf

If you're interested and can stand the pain start with the GA22-6974
manual known as the S/360 S/370 OEMI to get as close to the I/O
hardware as possible.  A shame though that SIO and similar commands
are locked up tight by the IOS (I/O Subsystem) in the MVS.  TPF still
lets you roll your own device drivers and interrupt handlers. The closest
you can easily get to doing IO the old fashoned way is with the EXCP
(EXecute Channel Program) command.  Work your way up through the simple
access methods like BTAM and then 3270 Data Streams.  By then you'll be
a dinosaur just like me. ;-)  You'll also need the 370 (POP) Principles
of Operations manual GA22-7000.  For a less detailed overview try a book
by Nallur S. Prasad "Architecture and Implementation of Large Scale IBM
Computer Systems"  1981 QED Information Sciences.  A very readable work
quite unlike the aforementioned IBM publications.  Good Luck.
-mjw-