david@sun.uucp (David DiGiacomo) (11/01/88)
The ARM's biggest advantage is its low cost. It's probably the cheapest 32 bit CPU around, depending on whether the Z80000/Z320 exists (does anyone know for sure?). However, I don't think VLSI has been aggressive enough on pricing. If you could get an 8 MHz ARM for $10, wouldn't you buy it instead of a 68000? VLSI isn't too aggressive (assertive?) about support, either. I'm sure I could get some info if I bugged a salesman, but just calling up and asking for data sheets didn't work too well. One bizarre thing about the architecture is the lack of 16 bit load/store instructions. I imagine this would add some excitement to writing a C compiler. -- David DiGiacomo, Sun Microsystems, Mt. View, CA sun!david david@sun.com
kers@otter.hple.hp.com (Christopher Dollin) (11/02/88)
David DiGiacomo says (referring to the ARM): | One bizarre thing about the architecture is the lack of 16 bit load/store | instructions. I imagine this would add some excitement to writing a C | compiler. One interesting thing reported in the ARM assembler book is the behaviour of the ARM on non-aligned word loads. The word with (address &~ 3) is loaded and rotated so that the low-order stuff is in the correct position. Thus you can load a half-word (assuming it's aligned on a half-word boundary) with one load and a mask operation. The book doesn't say if the same happens on store. And I haven't tried it out - yet. Whn I can afford the C compiler, or meet the guys who wrote it, I'll find out what *they* do. Regards, | "See the darkness all around Kers. | Is coming down on you ..."
pl@tut.fi (Pertti Lehtinen) (11/03/88)
From article <31748@oliveb.olivetti.com>, by chase@Ozona.orc.olivetti.com (David Chase): > > The versions of the CPU that I know of lack on-chip multiply or > divide, but the shifted operands and conditional instructions take a > lot of the curse out of that. The indexing modes on the load and > store instructions described below also help with this. > It has been twice an article on IEEE [micro|software] about ARM processor. Articles were written by some guy on VLSI-Technology (which produces chips for Olivetti). On later of those articles were 'multiply' and 'multiply and accumulate' intructions included. The chip is used in Acorn Archimedes, which employs 8 MHz clock and can achieve 4901 dhrystones. We also calculate some mandelbrot pictures with basic and 512*512 picture with 256 iterations took about 1 hour. Quite well for interpretive basic with software floats.