<b>Macs that won't startup in Mac OS 8 unless virtual memory is on

Previously, we reported a problem with virtual memory not working on certain computers after updating to Mac OS 8. Well, here's sort of the opposite problem: computers that won't startup unless virtual memory is on! [I still haven't figured out why this affects some computers but not others.]

Eric Stebelton writes: "When I turned off virtual memory and restarted my Power Mac 9500/200 with 72Mb of RAM, I got an alert that said the Finder could not start up because 'not enough memory was available.'" Reinstalling a new System Folder or starting up with extensions off was no help.

Similarly, Marc Tucker could not start up with virtual memory disabled (again even with all extensions also disabled). In his case, he got an "Illegal Instruction" error. The only work-around he found was to hold down the space bar at startup, bringing up Extensions Manager, and then continuing with his normally selected extensions enabled. He has a Performa 5300CD with 32Mb of RAM. He notes that a PRAM zap solved the problem for the next restart or so, but the symptom soon returned.

Update: Marc now informs me that this problem turned out to be due to a corrupted StartupScreen file.

Joseph Williams was at least able to start up his PowerBook 5300cs (with 48 Mb RAM) with virtual memory off. However, he gets "severe memory fragmentation problems. I can run only a handful of applicatio.ns (3 or 4) before I get 'Out of Memory' warnings. When I use Memory Mapper 1.3.5 to view memory usage, I am seeing large chunks of memory between applications that is essentially being wasted. However, when I turn ON Virtual Memory and set it to 1 MB, the fragmentation disappears."

All of this may be related to continuing reports of Mac OS 8 system software using increasing amounts of RAM over the course of a session.