binder@dosadi.DEC (The Stainless Steel Rat) (07/02/84)
This discussion doesn't seem to relate to Apples, but this is where it
started, so...
I can't fathom the Halt-and-branch instruction, maybe it should read
Branch-and-halt?
The MODCOMP II's instruction set includes a series of 26xx (hex)
opcodes. 26FF is unimplemented but not trapped out. It stores 26FF
into the location following the current PC and then executes it.
Discovered accidentally, ended up being used by at least one US Air
Force installation to clear >>core<< memory.
Cheers,
Dick Binder (The Stainless Steel Rat)
UUCP: { decvax, allegra, ucbvax }!decwrl!dec-rhea!dec-dosadi!binder
ARPA: binder%dosadi.DEC@decwrl.ARPA
Posted Monday 2nd July 1984, 09:02 EDT by DOSADI::BINDERMKrigel.ES@XEROX.ARPA (07/12/84)
HALT AND BRANCH? Actually the halt and branch instruction is common to many computers. It is used to set a primative break point (obviously); kinda' like a forced program PAUSE. I have the same instruction on a couple of mini-computers at work. It is vary handy when the operator must put some information into the switch register of a computer and somehow signal the CPU to continue processing. Marc