!pr0
New Version of DOS -- Patchers Beware

When Apple released the //e they apparently also slipped in a slightly revised version of DOS, called DOS 3.3e (or 3.3c.  Reports differ.)  The following information about the changes is from Tom Weishaar's DOStalk column in the April issue of Softalk.

The boot routine now throws a couple of new soft switches ($C00C and $C00E) and stores $FF in location $4FB.  These steps turn off the //e's 80-column mode during boot-up.

A routine at $B331 that calculates position in a random access file is now simplified.

Now for the biggie:  Another APPEND fix! (attempted)  According to Weishaar, they eliminated a bug that occurred maybe once in 10,000 tries by introducing a new bug that bites once every 256 calls.  Tom says that the most reliable method is to use the old DOS 3.3 and POKE -18851,0 before each APPEND.

The most significant thing about the APPEND change is where they put the patch:  at $BA69!  That used to be empty space and a popular place to install patches.  No more!  As a matter of fact, Bob's Fast Load patch in this issue goes into that area, and therefore should not be used with DOS 3.3e.

This means that //e users should be especially careful about installing published patches into DOS 3.3e, and all of us should quit using $BA69-BA95 for patches that will be distributed.



 !pr2
**

**  Not true!  See "New Version of DOS -- Patchers Beware".
