fmgst@unix.cis.pitt.edu (Filip M Gieszczykiewicz) (05/04/90)
Greetings. Anyone see what some of the high-end IBM 386 clones are doing too speed up their machines... (as if they need to...:-) The use SHADOW RAM. Basicly they copy the ROM to high speed STATIC RAM and then switch OUT the ROM and switch IN the RAM... The ROMS are usually 200-300 ns while the STATIC RAMs are 25-30 ns... nice. Anyone try it for the Apple... By the way (BTW) this also will work for any computer that has ROMs.... basicly anything... Anyone? -- _____________________________________________________________________________ "The FORCE will be with you. Always." It _IS_ with me and has been for 10 years Filip Gieszczykiewicz "..of future fame...." "Ok! So I have a dream..." FMGST@PITTVMS or fmgst@unix.cis.pitt.edu "My ideas, ALL MINE!!"
cyliao@eng.umd.edu (Chun-Yao Liao) (05/05/90)
In article <24029@unix.cis.pitt.edu> fmgst@unix.cis.pitt.edu (Filip Gieszczykiewicz) writes: > > Greetings. Anyone see what some of the high-end IBM > 386 clones are doing too speed up their machines... > (as if they need to...:-) The use SHADOW RAM. Basicly > they copy the ROM to high speed STATIC RAM and then > switch OUT the ROM and switch IN the RAM... The ROMS > are usually 200-300 ns while the STATIC RAMs are > 25-30 ns... nice. Anyone try it for the Apple... > By the way (BTW) this also will work for any computer > that has ROMs.... basicly anything... Anyone? A Ha! This sounds just like the way Zip Chip works... correct me if I'm wrong. (well, ZipChip doens' work exactly the way described above, but it copies whatever it needs into one of it's 8K cache memory and write back to main memory whenever requires.) -- cyliao@wam.umd.edu o NeXT : I put main frame power on two chips. @epsl.umd.edu o people: We put main flame power on two guys. @bagend.eng.umd.edu o :::::::::::::::::::::::::::::::::::::::::::: xxxxx@xxxxx.xxx.xxx (reserved) o RC + Apple // + Classic Music + NeXT = cyliao
whitewolf@gnh-starport.cts.com (Tae Song) (05/09/90)
> Greetings. Anyone see what some of the high-end IBM > 386 clones are doing too speed up their machines... > (as if they need to...:-) The use SHADOW RAM. Basicly > they copy the ROM to high speed STATIC RAM and then > switch OUT the ROM and switch IN the RAM... The ROMS > are usually 200-300 ns while the STATIC RAMs are > 25-30 ns... nice. Anyone try it for the Apple... > By the way (BTW) this also will work for any computer > that has ROMs.... basicly anything... Anyone? "SHADOW"ing is used on the GS. Details on shadowing is somewhat fuzzy, though.
cs4w+@andrew.cmu.edu (Charles William Swiger) (05/10/90)
The shadowing technique used to speed up the ROM for IBM's would be counterproductive for the Apple //gs for the simple reason that the //gs' ROM runs faster than its RAM currently does. Besides which, if Apple is going to redesign the motherboard in order to speed up its ROM chip then it had damn well _better_ speed up the rest of the computer too! The shadowing that the //gs does use is from RAM banks $00 and $01 to banks $E0 and $E1, for write and read-modify-write instructions only, and only when shadowing is enabled (via the "Quagmire" pseudo-register, I believe.) The purpose of this is to allow old 8-bit programs to run in the faster (2.7 MHz) bank $00-01 locations as much as possible, rather than the slow (1.0 MHz) bank $E0-E1 locations. (The $E0-$E1 banks contain the memory locations that the screen memory, I/O cards, and other hardware are actually mapped to. -- Charles William Swiger cs4w+@andrew.cmu.edu