Apple II
Technical Notes
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                                                  Developer Technical Support

Pascal
#17:    SYSTEM.APPLE Patch V2.0

Revised by:    Dan Strnad                                          March 1990
Written by:    Dan Strnad                                            May 1988

This Technical Note documents the Apple Pascal SYSTEM.APPLE patch version 2.0 
(available as part of the Apple Pascal 1.3 package from APDA), which fixes two 
Pascal system bugs found in the 64K and 128K, regular and run-time, version 
1.2 and 1.3 Pascal systems.  A companion program confirms the correct 
installation of these patches.
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SYSTEM.APPLE patch 2.0 corrects the following two bugs:

  1.  UNITSTATUS calls to device numbers six, seven, and eight 
      malfunction in Apple II Pascal 1.3.
  2.  On Apple IIGS machines, disk access to 5.25" drives may fail under 
      Apple II Pascal.

The following limitations exist with these patches:

  1.  Keyboard input from an external terminal does not work; however, 
      SYSTEM.APPLE patch 1.0 is also available to support external 
      terminals.  SYSTEM.APPLE patch 1.0 fixes only the UNITSTATUS 
      problem; it does not address the 5.25" drive problem on the Apple IIGS.

  2.  Type-ahead buffering may drop keystrokes under the following 
      circumstances:
        a.  On an Apple IIGS if the user has enabled keyboard 
            buffering from the Control Panel.
        b.  On an Apple IIc series computer, if an Apple II Pascal 
            program directly accesses the firmware-level keyboard 
            buffering.

Apple II Pascal 1.3 (and 1.2) still provide type-ahead keystroke buffering on 
all Apple IIs.

To use the patch program, X)ecute it from Pascal with the name PATCH.  To 
confirm the proper installation of the patch, perform an X)ecute with the name 
CONFIRM.

