bear@bu-pub.bu.edu (Blair M. Burtan) (11/14/89)
Does anyone think that Shadow RAM would be effective on an Ami? For those of you who have never heard of this concept, I'll explain. I was watching "the Computer Chronicles" a few days ago and they were talking about ways of speeding up system. One of the things they mentioned was "Shadow RAM." Basically this concept takes routines from ROM and places them in RAM. The claim is that RAM is faster than ROM. Would it be possible/worth the effort to take some of the graphics primitives from RAM and store them in ROM?
johnf@stew.ssl.berkeley.edu (John Flanagan) (11/15/89)
In article <42550@bu-cs.BU.EDU> bear@bu-pub.bu.edu (Blair M. Burtan) writes: >Does anyone think that Shadow RAM would be effective on an Ami? ... >Basically this concept takes >routines from ROM and places them in RAM. The claim is that RAM >is faster than ROM. Would it be possible/worth the effort to >take some of the graphics primitives from RAM and store them in ROM? This has been done, and it is definitely worth it. RAM is not inherently faster than ROM, but if you copy the Kickstart ROMS into fast 32-bit RAM, you get quite a performance increase over the 16-bit ROMS. Dave Haynie's SetCPU will do this if you have an A2620, and Brad Fowles' LUCAS/FRANCES board combination will also do this. I have the LUCAS/FRANCES combination, and there is easily a 2- to 4-fold increase in speed in the system drawing routines when the ROMs are remapped. John John Flanagan Space Sciences Laboratory johnf@sag4.ssl.berkeley.edu University of California (...!ucbvax!sag4.ssl!johnf) Berkeley, CA 94720 Manners Maketh Man. (415) 643-6308
daveh@cbmvax.UUCP (Dave Haynie) (11/15/89)
in article <42550@bu-cs.BU.EDU>, bear@bu-pub.bu.edu (Blair M. Burtan) says: > Does anyone think that Shadow RAM would be effective on an Ami? ... > The claim is that RAM is faster than ROM. Would it be possible/worth > the effort to take some of the graphics primitives from RAM and store them > in ROM? I think you got that last part backwards. But in any case, on a stock A500 or A2000, ROM is at least as fast as RAM. In general, ROM is as fast as any 16 bit Fast memory. Should you add a 68020 or 68030 CPU with 32 bit RAM, you then get into a situation where RAM is at least four times faster than ROM. You also have an MMU, and thus can use the SetCPU program to copy the entire contents of ROM into RAM, and then map that RAM to the location of the system ROM. This is going to affect CPU and ROM intensive operations, two of which are layers.library and the FFP math libraries on the Amiga. -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough
wade@pnet01.cts.com (Wade Bickel) (11/15/89)
bear@bu-pub.bu.edu (Blair M. Burtan) writes: >Does anyone think that Shadow RAM would be effective on an Ami? >For those of you who have never heard of this concept, I'll explain. >I was watching "the Computer Chronicles" a few days ago and they >were talking about ways of speeding up system. One of the things >they mentioned was "Shadow RAM." Basically this concept takes >routines from ROM and places them in RAM. The claim is that RAM >is faster than ROM. Would it be possible/worth the effort to >take some of the graphics primitives from RAM and store them in ROM? For those with 68020's or 30's there is a program (I believe by Dave Haynie of CATS) which will place the rom routines into the 32-bit memory for a noticable speed up of programs which use a lot of system calls. -Wade. UUCP: {nosc ucsd hplabs!hp-sdd}!crash!pnet01!wade ARPA: crash!pnet01!wade@nosc.mil INET: wade@pnet01.cts.com
farren@well.UUCP (Mike Farren) (11/30/89)
In article <42550@bu-cs.BU.EDU> bear@bu-pub.bu.edu (Blair M. Burtan) writes: >Does anyone think that Shadow RAM would be effective on an Ami? Probably not, at least not on a "standard" Amiga with a 68000. The whole reason for "Shadow RAM" is to allow ROM code to be executed without requiring wait states to be inserted for memory accesses to system code, ROM typically being slower than RAM. But the standard Amiga ROM is fast enough that no wait states are needed. A fast 68020 or 68030 would need wait states, but I understand (not being able to afford such a beast myself) that there are provisions for "Shadow RAM" type things in fast systems already. -- Mike Farren farren@well.sf.ca.usa