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CPM OPERATING SYSTEMS/CPM 2.X/CPM 2.2/PATCHES/CPM22PAT.09

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+                       CP/M   V2.2, Patch 09, DEBLOCK.ASM, 2/11/82
+
+          Copyright  1982 by Digital Research, Inc., Pacific Grove, CA  93950
+
+
+          Program:  DEBLOCK.ASM
+
+          Error Description:
+
+               The following modification affects only CP/M  systems  that  use
+          the  optional blocking and deblocking algorithms listed in Appendix G
+          of the CP/M Alteration Guide.  The  sector  blocking  and  deblocking
+          algorithms   provided   in  the  guide  work  improperly  in  certain
+          circumstances.
+
+          Patch Procedure:
+
+               Use the CP/M text editor to insert the following changes:
+
+
+                    Following the comment on line 111 of Appendix G:
+
+                          "read the selected CP/M sector"
+
+                    Insert the following two lines:
+
+                          xra     a            ;accum = 0
+                          sta     unacnt       ;unacnt = 0
+
+                    The next source lines remain as shown:
+
+                          mvi     a,1
+                          sta     readop       ;read operation
+
+                    Insert the following code in your BIOS Home routine:
+
+                     home:
+                          lda     hstwrt       ;check for pending write
+                          ora     a
+                          jnz     homed
+                          sta     hstact       ;clear host active flag
+                     homed:
+
+                    Continue with the rest of the home routine.
+
+
+
+               Licensed users are granted the right to include these changes in
+          CP/M software.  CP/M is a registered trademark of Digital Research.