Falsies

[COTTRELL, JAMES]

/*
@ In article <139200010 at uiucdcsb> robison at uiucdcsb.Uiuc.ARPA writes:
@ >
@ >> ... But no machine I know of has a `branch if true' instruxion...

No, *I* wrote that. *He* responded.

@ The 808x/Z80 families of microprocessors set the 'zero' flag in 'compare'
@ instructions, and have 'jump if zero', 'jump if non-zero', as well as the
@ corresponding conditional subroutine calls and and conditional returns.

Don't you think I know that? Doesn't everybody? You missed the point 
entirely! What I am saying is that at the assembly language level there
is no notion of pure true or false as a primitive condition. You may
decide whether a *particular* condition *is* true or false by using the
appropriate conditional branches, e.g. `branch if zero', `jump if 
carry', etc. ``But no machine I know of has a `branch if true' 
instruxion''. Now we are back to where we started from, robison will
send me a line about Burroughs having a `branch if true', you will
tell me about z80's & we have a recursive news item!

Now about the Burrough's. What exactly is their idea of truth? I hear
rumors that some of their machines are programmed in ALGOL. Is this
some kind of higher level concept? What's, uh, the deal?

@ They may be too small for you to consider them 'machines', but an awful
@ lot of work gets done on them.
@ 
@ Richard Klappal

That's right, a lot that's awful. Trying to program those things is
like an operating system thrashing. It does work tho!

	jim		cottrell at nbs
*/
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