Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!TAURUS.BITNET!finkel From: finkel@TAURUS.BITNET Newsgroups: comp.misc Subject: Re: Looking for computer folklore Message-ID: <8902210810.AA26436@MATH.Tau.Ac.IL> Date: 21 Feb 89 08:10:53 GMT Sender: usenet@ucbvax.BERKELEY.EDU Reply-To: Lines: 47 Newsgroups: comp.misc Subject: Re: Looking for Computer Folklore Summary: Expires: References: <911@mailrus.cc.umich.edu> <1069@zaphod.axion.bt.co.uk> <7017@fluke. Sender: Reply-To: finkel@virgo.UUCP (Udi Finkelstein) Followup-To: Distribution: Organization: Tel-Aviv Univesity Math and CS school, Israel Keywords: In article <7017@fluke.COM> kurt@fluke.BITNET writes: >This was not actually true of the 6800's we had. The instruction was to be >avoided, because nothing short of cycling power would stop it. It cycled >the address bus through all 64k addresses very rapidly and didn't respond to >interrupts. The effect was obvious if you had an Altair 680 (is that the >right number of zeros? It's been awhile) as we did. There's bunches of >folklore about unimplemented opcodes in the 6800, most of it useless. When >I think about the 6800, I am not even convinced it is microcoded, because of >the weird ways the unimplemented opcodes worked. About 5 years ago, I've seen a humorous article about a new '6502 cooprocessor' called the 7801, that has many new 'interesting' instructions such as: Stop for Coffee Break - SCB Branch if Power Off - BPO I don't remember the exact mnnemonics used, but I thin you all got the idea. There were many more 'useful' instructions, but I saw this article years ago, and I forgot most of it. There were about 30 more commands. The article appeared on '6502 & 6809 Journal', but I don't know what date it was. I think that the article may be 7-10 years old by now. I would appreciate it very much if someone who has it could type it in ( if it's not long, as I remember, and if it doesn't violate any copyright ), or at least tell me what issue it was. thanks in advance, udi ------------------------------------------------------------------------------- Udi Finkelstein | Bitnet: finkel@taurus.bitnet or finkel@math.tau.ac.il Tel Aviv University | Internet: finkel%taurus.bitnet@cunyvm.cuny.edu Israel | UUCP: ...!psuvax1!taurus.bitnet!finkel -------------------------------------------------------------------------------