Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!snorkelwacker!ira.uka.de!ifistg!cs3!homeis
From: homeis@cs3.ifistg.uucp
Newsgroups: comp.sys.transputer
Subject: undocumented instruction testhardchan
Message-ID: <1812@ifi.informatik.uni-stuttgart.de>
Date: 9 Mar 90 14:59:27 GMT
Sender: news@ifistg.uucp
Organization: IPVR, Univ. Stuttgart, W-Germany
Lines: 27
Reply-To:

Last Week I found in "asm.h" of Helios a transputer assembler instruction
"testhardchan" with two parameters ("chan" in Areg, "val" in Breg):
#define testhardchan_(chan,val) _operate(0x2d,chan,val)
  Helios might use this instruction, or it would not be in the include
file. I would like to use it too. By the way, this include file contains another
(officially) undocumented instruction, which I know only from the news:
#define start_()                _operate(0x1ff)
This instruction brings the transputer nearly into the same bootable state
as after applying a RESET signal, so that the transputer may be booted again
from it's links.
  I don't want to experiment with this undocumented testhardchan instruction.
I would be glad, if someone at Inmos would explain, what this instruction
does, and what the two parameters mean. (I would prefer an official
statement. :-)
  I have tried to write a fast code to find out, wether a LinkIn has received
a message or not, but all constructions with ALT were too slow.
In other words, I want to find out the status of the DMA unit.

Does the testhardchan instruction do this?
Which types of transputers are able to execute this instruction?
Does anybody know other undocumented instructions?

--------------
Dieter Homeister, Universitaet Stuttgart,
Institut fuer parallele und verteilte Hoechstleistungsrechner (IPVR)
7000 Stuttgart 1, Azenbergstr. 12, Tel 0711-121-1342
e-mail homeister@informatik.uni-stuttgart.dbp.de