Subject: Re: Trying to cram GS/OS into a walnut Path: lobby!newstf02.news.aol.com!portc05.blue.aol.com!cyclone-east.rr.com!news.rr.com!news-east.rr.com!news-out.cwix.com!newsfeed.cwix.com!newsfeed.clear.net.nz!news.wlg.netlink.net.nz!news.actrix.gen.nz!dempson From: dempson@actrix.gen.nz (David Empson) Newsgroups: comp.sys.apple2 Date: Tue, 8 Feb 2000 21:23:25 +1300 Organization: Empsoft Lines: 37 Message-ID: <1e5lvvp.7jxu3zrk61fiN%dempson@actrix.gen.nz> References: <20000205125855.22451.00000205@ng-bh1.aol.com> NNTP-Posting-Host: news2.actrix.gen.nz User-Agent: MacSOUP/2.4.2 X-Original-NNTP-Posting-Host: 202.49.157.176 Supertimer wrote: > jonINTERNETrelayCHAT@napaVALLEYnet.CLARInet (Jon Bettencourt) wrote: > > >If I were to make a ROM disk for the IIgs, how would I do it? Can it be as > >big as 6.5MB? In what format should I save it in? Would it be the same as > >an HDV file? I'm feeling like putting the complete GS/OS, plus a few extra > >things, on there and booting off it. > > There are two types of ROM disks. Apple IIGS ROM disks and > Apple II ROM disks. Apple IIGS ROM disks are addressed > through the memory expansion slot. The ROM disk can be up > to a little less than 8MB in size (8MB minus the amount of > ROM on the IIGS). Are you sure about that? The IIgs memory slot design allows for a ROM disk which occupies banks $F0 through $F7, and it can be extended up to the motherboard ROM (which breaks Apple's rules for reserved pages). This means that a ROM disk can officially occupy 512K, and unofficially 768K (ROM 3) or 896K (ROM 1). A specially designed card could use bank switching to increase the amount of ROM available, but it can't use banks below $F0, because the enable signal doesn't go active for these banks. > I don't think there were any genuine ROM disks, There was at least one early card which had genuine ROM disk support. There was also the OctoRAM ESP, which was a static RAM disk with battery backup which pretended to be a ROM disk (and could be write-protected with a jumper). It was a piggyback card for the OctoRAM. -- David Empson dempson@actrix.gen.nz Snail mail: P O Box 27-103, Wellington, New Zealand