michael@vuecho.UUCP (08/14/87)
>>> >>> When I try to boot my 128K MAC from some disks I get a frowning face >>> sitting on top of a 0f0064 error code on a blank screen. >>> Once the system is booted inserting some >>> disks causes the error: 'this disk is unreadable to appear'. >>> While working with a Lisa (MacWorks, MacXL) the following occured: I turned the computer off. The next workday I turned it back on and got the infamous sad mac (0f0064). After much tinkering to determine what the disk id was (it's #4) I was able to read the boot blocks, vol info, master directory block, try to mount it, etc.. The reaction to MountVol was error -64 ( I think). In any case the error meant badMDB - bad Master Directory Block. Apparently during mounting of a volumn MountVol compares the number of free allocation blocks in the MDB with the word value stored in the volumn information block. If these are equal the result is ioError = -64 (i.e. badMDB). I solved this problem by treaking the value in the volumn info block to the amount of free space indicated by the MDB. And voila, booted. To be safe, I re-formated after backing up to floppy. All this is said not to counter what has been said already, but there are other problems. I suspect the message 'disk is unreadable' refers to a bad MDB as a double sided disk would (I expect) result in 'not a macintosh disk' as 64K roms only know about MFS disks. Regarding Bad drives: we had one machine (of 13) that had a bad drive. It was replaced and the machine has worked fine since.