iris@Lindy.STANFORD.EDU (IRIS) (03/17/88)
Thanks to everyone who responded to my original posting about the changing size of RAM disks created with RamStart. It seems that RamStart doesn't install the same *size* RAM disk each time; rather, it installs it in the same area of memory. So if the size of the Macintosh RAM cache changes (with a corresponding move of BufPtr) then the size of the RamStart RAM disk will grow or shrink. If anyone is interested, I have found two solutions to this problem: 1) Use the program RamSnap by Dove. This program is shipped with all their products, and is supposedly available separately. RamSnap seems to keep the size of the RAM disk constant regardless of the size of the cache. 2) Disable the Macintosh RAM cache. In the system folder, the RAM caching code is in the CACH 1 resource in the System File. At the time an application is launched, INIT 35 moves BufPtr down as necessary for the size of the RAM cache as specified in the conrol panel. It then brings in the balance of the caching code from the CACH 1 resource. All this is documented in Tech Note 81. If you remove these two resources, BufPtr doesn't move down and caching doesn't happen. Disassembling INIT 35 indicates that it's removal shouldn't cause any problems (if anyone knows of any reason why INIT 35 *shouldn't* be removed (besides from the fact that "the user should always be in control of the RAM cache") please let me know). So far preliminary testing with this setup indicates no problems whatsoever and RamStart RAM disks of consistant size. Again, many thanks to all of you who pointed me in the right direction. David Finkelstein Stanford University davef@jessica.stanford.edu