info-mac@uw-beaver (info-mac) (12/01/84)
From: David.Anderson@CMU-CS-K.ARPA I would like to construct an environment on my FatMac that looks exactly like a 128K machine for testing out applications that I write distributing them. Has anyone figured out how to do this? I know that the screen and sound buffers are shifted up by $60000, but I've been peeking around in memory to find out what else is different. The only other difference that I see is that the system heap extends from $B00 to $CB00, for a total of 48K bytes, vs. only 16.5K on the smaller Mac. Why and how is this done? My guess is that this is probably done by one of the 3 original INIT resources in the system -- anyone know for sure? Another point of concern is the RamDisk -- I wonder if I've found a bug. The INIT 3 resource slides BufPtr down to $28000, and I see in the RamDisk sources that it occupies $50000 bytes, or out to $78000. However, when running without the RamDisk, but with MacsBug, BufPtr is $76640. It appears to me that if you fill up the RamDisk you'll overwrite part of the debugger. P.S. I've found that many of the PD programs I have don't work on my FatMac -- dbrothers' music engine, the Clock with numbers that transform before your eyes, and others. (And I found out the hard way; I offered to have my Mac play some music for a guest, and after waiting for it to initialize the waveforms, etc., out came nothing.) If you do your own screen or sound hacking, make sure to use the $7a700 and $7fd00 addresses -- they'll map around on a 128K Mac.
info-mac@uw-beaver (info-mac) (12/04/84)
From: DUFLON.WBST@XEROX.ARPA 1) With diskutil program one can create a truncated fat mac (This simulates a 128K application heap ONLY). The fun thing is that the heap is cut back after the debugger is installed. To obtain this feature, hold the command and option keys down and click on the "Wr Boot Blks" (sic) button. 2) (What a segue...)The memory configuration and the enumeration of INIT types is done with the boot blocks, the first two blocks on the disk. 3)Finally, the clock program on the shipped Through the Looking Glass disk(nee Alice) is fixed for 512K's. Steve Capps