TI MSP430
in [Embedded]
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From: Mark Borgerson on 10 Apr 2006 01:14 In article <4438F445.5EF07B7D(a)yahoo.com>, cbfalconer(a)yahoo.com says... > larwe wrote: > > Gary Reichlinger wrote: > > > >>>basis of its similarity to the PDP-11(1). > >> > >> Do you guys belong to AARP? > > > > Not yet, but the curmudgeonliness flux density is high in the > > engineering field, so it's forgivable that you would ask the > > question :) > > What we really need is a PDP-8 on a chip. > > "He who does not study is doomed to repeat it." (couldn't track down the author). Intersil 6100. Mark Borgerson
From: David Brown on 10 Apr 2006 04:13 Jonathan Kirwan wrote: > On Sun, 09 Apr 2006 00:16:04 GMT, Marc Ramsey <marc(a)ranlog.comREMOVE> > wrote: > >> larwe wrote: >>> MSP430 is a truly elegant architecture, there's no denying it. von >>> Neumann simplicity, totally transparent handling of registers and >>> addressing modes; I really can't find much to fault with it (except >>> maybe the way info memory is handled). But: >> Of course, the architecture is a simplified version of the TMS9900 CPU, >> which was derived from the TI 990 minicomputer, which was in turn a >> rip-off of the PDP-11 ISA, with slight changes (fewer addressing modes, >> allowing twice as many registers) to avoid patent issues... > > I have a few comments about a pdp-11 comparison at: > > http://users.easystreet.com/jkirwan/new/msp430.html > > Jon Your comments are (as far as I can tell) factually correct, but the reaction that springs to mind is "so what?". As an embedded programmer, I really do not care how a particular embedded micro compares to an old minicomputer cpu (other than for historic interest, of course - in which case it definitely is interesting). And as for possibly misleading marketing from TI - it's not exactly new or unusual! What is much more relevant is whether the register set and addressing modes of the msp430 really are appropriate for their target applications, or whether they would have been better off with the PDP-11 arrangement. I'm far from convinced - certainly, the example you gave (PC-relative CALL) is obscure indeed, and I think the benefit of more registers well outweighs this missing feature. One thing that is definitely missed, however, is all four addressing modes as the destination for two-operand instructions. At the very least, there should have been a hack in the MOV instruction to allow @Rn and @Rn+ modes in the destination. As for the missing PDP-11 addressing modes, they are not such a great loss. The indirect modes are almost entirely superfluous when you have enough registers to hold pointers in registers, rather than having to have them in memory or on the stack. It's not often that pointers to pointers turn up, at least not in embedded programming. Auto-decrement modes are nice, but how often are they used in practice? *(p++) far outweighs *(--p), as long as you have a stack pointer and push/pop instructions. Perhaps it would be a useful mode for MOV, but not otherwise. So if you want to say that the msp430 is not as close to the PDP-11 as TI marketing seems to think, then I fully agree. But if you think that's a bad thing, then I disagree. mvh., David
From: Leon on 10 Apr 2006 05:41 Mark Borgerson wrote: > In article <4438F445.5EF07B7D(a)yahoo.com>, cbfalconer(a)yahoo.com says... > > larwe wrote: > > > Gary Reichlinger wrote: > > > > > >>>basis of its similarity to the PDP-11(1). > > >> > > >> Do you guys belong to AARP? > > > > > > Not yet, but the curmudgeonliness flux density is high in the > > > engineering field, so it's forgivable that you would ask the > > > question :) > > > > What we really need is a PDP-8 on a chip. > > > > > "He who does not study is doomed to repeat it." > (couldn't track down the author). > > Intersil 6100. Many years ago DEC was giving away sample chips with a PDP-11 on them. I got one and started to design a small system round it, but never got round to building it. Leon
From: Gary Reichlinger on 10 Apr 2006 09:26 On Sun, 9 Apr 2006 19:20:45 PST, mojaveg(a)mojaveg.iwvisp.com (Everett M. Greene) wrote: >Watch your mouth there, you young whippersnapper! >We do not mention the "O" word in polite company. Actually, I am within the age range for AARP, but have opted not to join. However, some of this discussion is of things that were definitely before my time.
From: SMS on 10 Apr 2006 13:23
Gary Reichlinger wrote: > On 8 Apr 2006 17:43:20 -0700, "larwe" <zwsdotcom(a)gmail.com> wrote: > >> "Now, it's an obscure but well-recognized ritual amongst engineers and >> computer scientists to gauge the architecture of any new device on the >> basis of its similarity to the PDP-11(1). > > Do you guys belong to AARP? Is there a member discount on the TI MSP430 (or any other micro-controller?). |