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87 lines
3.1 KiB
TeX
87 lines
3.1 KiB
TeX
.MB +5
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.MT -3
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.LL 65
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.PN 148
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.HE MP/M User's Guide
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.FT (All Information Herein is Proprietary to Digital Research.)
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.sp
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.ce
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APPENDIX J: MP/M DDT Enhancements
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.pp
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The following commands have been added to the MP/M debugger
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to provide a function similar to CP/M's SAVE command and to
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simplify the task of patching and debugging PRL programs.
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.sp 2
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W: WRITE DISK
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.pp
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The purpose of the WRITE DISK command is to provide the
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capability to write a patched program to disk. A single parameter
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immediately follows the 'W' which is the number of sectors (128
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bytes/sector) to be written. This parameter is entered in hexadecimal.
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.sp 2
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V: VALUE
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.pp
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The purpose of the VALUE command is to facilitate use of the
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WRITE DISK command by computing the parameter to follow the 'W'. A
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single parameter immediately follows the 'V' which is the NEXT
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location following the last byte to be written to disk.
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.pp
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Normally a user would read in a file, edit it, and then write
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it back to disk. The read command produces a value for NEXT. This
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value can be entered as a parameter following the 'V' command and
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the number of sectors to be written out using the 'W' command will
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be computed and displayed.
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.sp 2
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N: NORMALIZE
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.pp
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The purpose of the NORMALIZE command is to relocate a page
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relocatable file which has been read into memory by the debugger.
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To debug a PRL program the user would read it in with the 'R'
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command and then use the 'N' command to relocate it within the
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memory segment the debugger is executing.
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.sp 2
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B: BITMAP BIT SET/RESET
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.pp
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The purpose of the BITMAP BIT SET/RESET command is to enable
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the user to update the bitmap of a page relocatable file. To edit
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a PRL file the user would read the file in, make changes to the
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code, and then determine the bytes which needed relocation (E.G.
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the high order address bytes of jump instructions). The 'B'
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command would then be used to update the bit map. There are two
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parameters specified, the address to be modified (0100H is the base
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of the program segment), followed by a zero or a one. A value of
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one specifies bit setting.
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.AD
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.bp
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.sp 2
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.ce
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APPENDIX K: Page Relocatable (PRL) File Specification
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.sp
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.pp
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Page relocatable files are stored on diskette in the
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following format:
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.li
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Address: Contents:
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------- --------
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0001-0002H Program size
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0004-0005H Minimum buffer requirements (additional memory)
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0006-00FFH Currently unused, reserved for future allocation
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0100H + Program size = Start of bit map
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.ad
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.pp
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The bit map is a string of bits identifying which bytes are
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to be relocated. There is one bit map byte per 8 bytes of program.
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The most significant bit (7) of the first byte of the bit map
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indicates whether or not the first byte of the program is to be
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relocated. A bit which is on indicates that relocation is
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required. The next bit, bit(6), of the first byte of the bit map
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corresponds to the second byte of the program.
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.br
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