Post AaRXRexVRb7mVmUBk0 by sgf@mastodon.xyz
 (DIR) More posts by sgf@mastodon.xyz
 (DIR) Post #AaRXRaghK9IpGUahzE by sgf@mastodon.xyz
       2023-09-26T21:17:42Z
       
       0 likes, 1 repeats
       
       I'm happy with this: An emulated classic (24-bit 68K) Mac with 5MB of RAM. No original classic Mac had >4MB of RAM as the ROM got in the way (*). I've patched the ROM & System 6 to support a relocated ROM. The main constraint on increasing RAM to e.g. 15MB is now the memory-mapped I/O, which also needs relocation. The eventual goal is a physical large-memory classic Mac.(*) The Mac Portable's ROM location allows up to 9MB of RAM, but it's a bit weird, and I'm going for the full 15+MB.
       
 (DIR) Post #AaRXRcmRXl5RktIKDg by sgf@mastodon.xyz
       2023-09-26T21:18:34Z
       
       0 likes, 0 repeats
       
       (Reverse-engineering and patching over at https://github.com/simon-frankau/big-classic-mac)
       
 (DIR) Post #AaRXRexVRb7mVmUBk0 by sgf@mastodon.xyz
       2023-09-28T21:26:01Z
       
       0 likes, 0 repeats
       
       I'm now drawing with the Macintosh Portable on 9MB for a 24-bit Mac. Moving the SCSI hardware out of the way was easy, finding the assumption of a maximum of 8MB RAM in the MoveHHi system call, OTOH, was a right pain. Perhaps I should have started with the Mac Portable ROM. Ah well.
       
 (DIR) Post #AaRXRgmwdprgBbYmYa by sgf@mastodon.xyz
       2023-09-29T22:48:04Z
       
       0 likes, 0 repeats
       
       Now up to 13MB of RAM, comfortably exceeding the Mac Portable. Possibly the most RAM a classic Mac has ever seen, even if it's virtual. :p
       
 (DIR) Post #AaRXRikBN4qMFcHbWq by sgf@mastodon.xyz
       2023-10-01T09:35:13Z
       
       0 likes, 0 repeats
       
       Last one I promise (for now :p).15.5MB is as far as I think worth's trying with a 24-bit (16MB address space) Mac. The rest goes to ROM (256KB) and memory-mapped I/O.Next steps are probably to see if System 7 will run (complete with MultiFinder, to use all that RAM) and run a bunch of classic apps to exercise the thing.Then, at some point I should work out what drivers to write to make this work on a DIY Mac clone...