stout@hpscdc.scd.hp.com (Tim Stoutamore) (02/01/90)
The WDM opcode is a one byte intruction reserved for use as the first byte of two byte instructions in the future 32 bit processor 65832. In the 65C02, WDM would be a no-op because all unimplemented byte codes are treated as no-ops by the 65C02 (not so the 6502). Tim Stoutamore
bird@cbnewsd.ATT.COM (j.l.walters) (02/01/90)
From article <5424@hydra.gatech.EDU>, by ccastbs@prism.gatech.EDU (Shannon Bell): > Could someone please tell me what WDM is supposed to do? It's > opcode 42,... It stands for William D. Mensch, the designer of the 65816. As I remember, it is reserved as an expansion instruction of some sort. (Math coprocessor?) The true answer is in the Lichty & Eyes book on programming the 65816. -- Joe Walters att!ihlpf!bird IH 2A-227 (708) 979-9527
rnf@shumv1.uucp (Rick Fincher) (02/01/90)
In article <2062@ultb.isc.rit.edu> lmb7421@ultb.isc.rit.edu (Les Barstow: Phoenix) writes: >the WDM instruction is reserved for future use - presumably for two-byte >instructions which would be needed for the 65832 in order to access the >longwords and longword addresses which that chip might be capable of... > >Stands for something like Western Design (Macro/Mnemonic)... > Actually it stands for William D. Mensch, the chip designer's name. Rick Fincher rnf@shumv1.ncsu.edu
johnmac@fawlty.towers.oz (John MacLean) (02/05/90)
>Stands for something like Western Design (Macro/Mnemonic)... > >Les Barstow | Your best flamage could be here! I always thought WDM stood for William De Mench. Is this true? John MacLean. -- This net: johnmac@fawlty.towers.oz.au Phone: +61 2 427 2999 That net: uunet!fawlty.towers.oz.au!johnmac Fax: +61 2 427 7072 Snail: Tower Technology Unit D 31-33 Sirius Rd, Lane Cove, NSW 2066, Australia.
cs122aw@ux1.cso.uiuc.edu (Scott Alfter) (02/06/90)
Here's a possibility. The 65816's instruction set, including the "WDM"
mnemonic, is full. All 256 positions are taken. What, however, if they want
to add new features in the future? They'll use this one code that's left as
a type of "hook" to open up another set of 256 "sub-opcodes." This setup would
be like the "&" command in BASIC.
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