Path: utzoo!attcan!uunet!cbmvax!daveh From: daveh@cbmvax.UUCP (Dave Haynie) Newsgroups: comp.sys.amiga.tech Subject: Re: 68030, how much faster? Message-ID: <4446@cbmvax.UUCP> Date: 8 Aug 88 20:31:03 GMT References: <880806111207.003@Janus.MRC.AdhocNet.CA> Organization: Commodore Technology, West Chester, PA Lines: 52 in article <880806111207.003@Janus.MRC.AdhocNet.CA>, svermeulen%Janus.MRC.AdhocNet.CA@UNCAEDU.BITNET (Steve Vermeulen) says: > Regarding the 68030... > +From: cthulhu@athena.mit.edu (Jim Reich) > +Mac compatibility is pretty unlikely, considering that Jobs isn't with Apple > +anymore... Do Marketing and Head Honcho types at Apple determine hardware and software compatibility all that much? Given that the 68020 runs a decent portion of Apple software in a Mac II, the 68030 would be expected to do pretty similarly. Turning on the data cache would cause the most trouble with self-modifying code in the Apple Mac world, since they really aren't concerned with DMA or true context switching. > +Does it support Memory Management compatibly with the A2620?) Yup. All 68030s have an on-chip MMU that's a subset of the 68851 MMU used on the A2620, and Commodore-Amiga only supports the 68030 compatible subset. > While at AmiExpo in January I pestered the CSA sales rep until he allowed > me to do a crude compiling benchmark on his 020 and 030 board.... > Anyway, when we ran it (timing by SEIKO) both the 020 and 030 did the > compile and link in exactly (to less than 1%) the same time. That's pretty much what you'd expect in a plug-replacement setup with the 68030 data cache disabled. In the ideal situation, a 68030 will go just over twice as fast as the 68020+68851 combination at a given clock speed, with data cache off. Even faster, of course, with it on. However, that extra speed is fully dependent on memory architecture -- with the same memory system, and the data cache off, you won't be able to tell the difference. Even the ability to run the data cache depends on a few simple but important elements in the memory system, and any adaptor board that doesn't take these elements into account won't allow data caching. The Amiga adds an extra twist to this, in that CHIP memory and registers must never be cached, and that DMA devices on the expansion bus must really account for data caching in their device drivers. > Stephen Vermeulen > Author: Express Paint ^^^^^^^^^^^^^ Saw this at C Ltd's Suite at Comdex. Nice program. Who says DPaint has no competition? > Chairman: AMUC. -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {ihnp4|uunet|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy "I can't relax, 'cause I'm a Boinger!"