Path: utzoo!utgpu!water!watmath!clyde!rutgers!uwvax!oddjob!hao!gatech!psuvax1!vu-vlsi!cbmvax!daveh From: daveh@cbmvax.UUCP (Dave Haynie) Newsgroups: comp.sys.amiga Subject: Re: Hurricane 68020 & O/S speedup Message-ID: <3146@cbmvax.UUCP> Date: 14 Jan 88 20:03:09 GMT References: <271@dalcsug.UUCP> Organization: Commodore Technology, West Chester, PA Lines: 34 in article <271@dalcsug.UUCP>, peter@dalcsug.UUCP (Peter Philip) says: > Keywords: 68020 AmigaDOS ROM > An interesting technique used to speed up accesses to the ROM > BIOS in the current crop of IBM compatible 80386 machines is to copy > the BIOS to 32 bit memory and reroute the system calls. Even for a > relatively primitive OS like PC-DOS the speedup is quite significant. > For a machine like the Amiga, which interacts with almost all hardware and > software (IE: multitasking overhead) through system routines, the speed gained > by moving KS/ROM routines to 32 bit/fast memory vs 16 bit could be very large. > Just how feasable is this? I know you lose 192K or maybe 256K, but it might > be worth it, at least as an option. Buy a Commodore-Amiga A2620 board if you can wait a little longer. At least for A2000s. This board has an MMU on it. Among other things an MMU can do for you, it can translate addresses. So you allocate an appropriate 256K block of memory. Copy ROM into it. Set up the MMU to translate that chunk of memory to the normal ROM addresses. You now have the OS in RAM, and no problems with relocating the ROM or such things. > After all, the whole OS uses relative addressing, right? Wrong. Object files contain relocation information used by the loader to relocate. Once located, they aren't necessarily using relative addressing. The problem with relative addressing on the 68000 is it limits you to 16 bits relative. > R. Andrew MacRae > Respond to the net and I will forward all replies to Andrew. > -Peter Philip -- Dave Haynie "The B2000 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!"