daveh@cbmvax.UUCP (Dave Haynie) (04/21/89)
in article <6919@saturn.ucsc.edu>, roman@jupiter.ucsc.edu (Roman Baker) says: > Keywords: 68000 > I heard from somebody that the 68000 uses 32 bit internal and 16 bit > external. What is this supposed to mean. Does it used 32 bits for internal > calculations or addressing but only have a 16 bit bus? That's basically it. All registers are 32 bit wide, and so is the address space. Externally, the 68000 talks to the world on a 16 bit bus, and only 24 bits worth of address are brought off-chip. Internally, there are actually three 16 bit ALUs, two of which team up for 32 bit operations (which accounts for the longer time some 32 bit operations take, even when you're not fetching additional memory). This has been a tremendous advantage for the 68000 family, since with the 32 bit programming model, you don't have to change correctly written 68000 code to run on any of the full 32 bit members of the 680x0 family. > Roman Baker > roman@jupiter.ucsc.edu > r -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy Amiga -- It's not just a job, it's an obsession