braner@batcomputer.TN.CORNELL.EDU (braner) (11/02/86)
[] If you want to use the RAM disk program I've posted as a drive other than 'D', you have to patch it. This patch is essential if you want to use a hard disk together with the RAM disk. Here is an old hint: >From: jdg@elmgate.UUCP (Jeff Gortatowsky) > {allegra,seismo}!rochester!kodak!elmgate!jdg >Subject: Reset survivable RAM disk and Atari HD problem fixed! >Date: 3 Oct 86 > >Well after a bit of digging and disassembly my brother (a sharp troop) >found the correct combination to get the reset surviving RAM disk to play >as drive F: in a HD system (Atari 20meg). First, as was mentioned >before on this news group you need to change the bit set in the 'drivebits' >variable down in low memory. The BSET #3,d0 needs to be BSET #5,d0 (for >drive F:). The other patch is applied to the compare instruction in the >code that is executed when RWABS calls the RAM Disk. The RAM disk checks >the device number and if it's not the right number it passes control >through a JMP instruction to the Hard disk vector the RAM disk saved at >boot time. The above patches imply that the RAM disk need be executed >AFTER the hard disk driver is installed, so it may take over and save >the hard disk vectors. What I think was meant: Change the bytes at the following offsets from the beginning of the ".prg" file: offset old value(for drive D) new value (for drive F) ====== ====================== ======================= $145 (325) 03 05 $173 (371) 03 05 $181 (385) 03 05 $193 (403) 03 05 The first one is the "BSET #3,D0" in the installation, the other three are "CMP #3,x(A7)"s in handling calls to disk device drivers. For drive C instead of F, use the value 02. To change the default RAM disk size, change the byte at offset $B3 (179): The value is the size in units of 64K, e.g. 03 for a default size of 192K, 09 for 576K. WARNING: These are untested speculations!!! If somebody tests this (with a hard disk, if possible), please tell us! Jeff, if you're out there: please confirm &/or post the fix and the disassembly! - Moshe Braner
rbk@akguc.UUCP (rbk) (11/04/86)
<><><><><><><><> > If you want to use the RAM disk program I've posted as a drive other > than 'D', you have to patch it. This patch is essential if you want to use > a hard disk together with the RAM disk. Here is an old hint: > ... (some lines deleted) ... > What I think was meant: Change the bytes at the following > offsets from the beginning of the ".prg" file: > > offset old value(for drive D) new value (for drive F) > ====== ====================== ======================= > > $145 (325) 03 05 > $173 (371) 03 05 > $181 (385) 03 05 > $193 (403) 03 05 > > The first one is the "BSET #3,D0" in the installation, the other three > are "CMP #3,x(A7)"s in handling calls to disk device drivers. > > For drive C instead of F, use the value 02. > > To change the default RAM disk size, change the byte at offset > $B3 (179): The value is the size in units of 64K, e.g. 03 for > a default size of 192K, 09 for 576K. > > WARNING: These are untested speculations!!! > If somebody tests this (with a hard disk, if possible), please tell us! > Jeff, if you're out there: please confirm &/or post the fix and the > disassembly! > > - Moshe Braner The patch works as advertised; thanks Moshe! BTW, I changed the byte to "0C" for Drive "M" since I already have a hard disk partition called "F". R. Brad Kummer {ihnp4, seismo!akgua}!akguc!rbk AT&T Bell Labs Atlanta, GA