|Hi Larry, |
you should read as well the T9 Instruction Set Manual p.97ff.
Gesendet mit meinem HTC
----- Reply message -----
Von: "Larry Dickson" <tjoccam@xxxxxxxxxxx>
An: "Occam Family" <occam-com@xxxxxxxxxx>
Betreff: Question on T9000
Datum: Do., Dez. 22, 2016 22:21
I donâ€™t know who to address this to, so I will ask you all. Is there someone out there who worked on the T9000 protected mode system?
I picked up a copy of "THE T9000 TRANSPUTER HARDWARE REFERENCE MANUALâ€? at
and looked at the communication instructions in, out, etc. (p 95). They were all marked P (Instruction not allowed in P-process). By contrast, move was marked M (Invalid memory-address for P-process), as were ldnl, stl, stnl, etc. Thus, the latter are legal given good addresses, and the former are not legal even if addresses are good, despite the famous CSP equivalence of
b := a
chan c :
c ! a
c ? b
Why are the communications illegal? Was it because only one "current processâ€? is allowed, or was it too hard to keep control over virtual memory while waiting for the second process, or was development effort too great for something which does not exist in C-language user-space? Was communication off-loaded to the L-process belonging to that P-process, or was it just not modeled?
By the way, thank you everyone who helped me to a copy of Michael Pooleâ€™s ETC paper in WoTUG-21. The book arrived, and has several other treasures besides ETC. For instance, â€œAn optimizing multiprocessor occam system for the PowerPCâ€? has true interrupt-level high priority, simple edge links, and even an extension of the configuration (.PGM) files!