Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!ucbvax!hplabs!hpcc05!hpcuhb!hpindwa!tribby From: tribby@hpindwa.cup.hp.com (David Tribby) Newsgroups: comp.sys.apple2 Subject: Re: Re: Apple IIGS's Memory Limit (17Megs) Message-ID: <54240034@hpindwa.cup.hp.com> Date: 26 Jun 91 17:30:28 GMT References: <864@generic.UUCP> Organization: HP Info Networks Div/Cupertino CA Lines: 52 I have an OctoRAM card in my ROM01 GS. Although I currently only have two meg on it, I could load it up to eight meg. I also have an add-on board, ESP, that uses battery-backed-up static RAM to form a ROM disk. This ROM disk currently has a whopping 128K on it, but it is expandable out to 512K (1/2 meg). One of the reasons I bought the OctoRAM back in '88 was that it was designed to allow all of the expansion memory in the IIGS specification: 8 meg of RAM and 1/2 meg of ROM. My memory map looks like this: Bank (64K each) $00 - $01 Built-in ROM01 RAM $02 - $21 2-meg on OctoRAM $22 - $81 Another 6-meg could be added to OctoRAM $E0 - $E1 "Slow" built-in ROM01 RAM $F0 - $F1 128K on ESP (ROM disk) $F2 - $F7 Another 384K available for ROM disk $F8 - $FD "Reserved ROM space" (some used by ROM03) $FE - $FF ROM01 firmware A few years back, I read about incompatibilities between the upper 4 meg of expansion RAM and DMA, so if I fully load the OctoRAM, banks $42 - $81 would not be compatible with all cards that use DMA. When the ROM03 GS was released, it came with 1 meg of built-in memory and used some of the reserved ROM space ($FC - $FD). If I were to fully load my OctoRAM and ESP cards and put them in a ROM03, wouldn't the memory look like this: Bank (64K each) $00 - $FF Built-in ROM03 RAM $01 - $4F 4-meg on OctoRAM compatible with DMA $50 - $8F Another 4-meg on OctoRAM incompatible with DMA $E0 - $E1 "Slow" built-in ROM03 RAM $F0 - $F7 512K on ESP (ROM disk) $F8 - $FB "Reserved ROM space" $FC - $FF ROM03 firmware That would give me a 9 meg GS (9.625 if you add the "slow" RAM and ESP). Would this work in a ROM03? Have I missed any "reserved" memory? -- Dave Tribby - - - - - tribby@hpda.cup.hp.com or tribby@cup.hp.com or hplabs!hpda!tribby