🚀 go-pugleaf

Further to the recent discussion on undocumented transputer instructions,
here are some more instructions that I am aware of (in addition to the
"testhardchan" instruction mentioned previously).  I know little more
about these instructions other than their operation codes and their
mnemonics:

    Operation code (hex)		Mnemonic
    --------------------		--------
		23			testlds
		24			testlde
		25			testldd
		26			teststs
		27			testste
		28			teststd
		2D			testhardchan
		80			fpsttest
		85			fpldtest
		A7			fpentry3
		A9			fpentry2

>From the mnemonics, one can guess at what some of these instructions might
do.  In particular, the two extra fpentry instructions look interesting.
If they work like the normal fpentry instruction then they could lead to
a whole load of extra floating point instructions.  If you are familiar
with the transputer instruction set then you will see that these extra
instructions fill in some of the "gaps" between the documented instructions.

Here are some questions.  Can anyone on the transputer grapevine provide
any answers?

    1)	Are there any more undocumented instructions?

    2)	What do these instructions do?  How do they affect registers and
	what are the cycle times?

    3)	Are any of these instructions of any real use other than for testing
	purposes?

    4)	Which instructions are supported on which types of transputer?


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Peter Clare
THORN EMI Central Research Laboratories
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