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78 lines
2.6 KiB
Plaintext
78 lines
2.6 KiB
Plaintext
CP/M V2.2
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Application Note 07, 2/20/82
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Changing the Restart Number in DDT
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Copyright 1982 by Digital Research
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CP/M is a registered trademark of Digital Research.
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DDT is a trademark of Digital Research.
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Compiled November 1982
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Applicable products and version numbers: CP/M V1.4, V2.0, V2.1,
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and V2.2
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Program: DDT.COM
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DDT uses RST 7 (machine instruction 0FFH) to set break points.
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To change the restart number, modify the three bytes indicated by ??
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in the following procedure for a new restart instruction and
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location. The restart instruction uses the bit pattern 11XXX111,
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where XXX is the restart number you use. (AFH is RST 1, B7H is RST
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2, and BFH is RST 3.) The restart location is usually the restart
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number times 8. Do not use RST 0 because it is reserved for CP/M.
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The following procedure applies to DDT supplied with CP/M V2.1
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and V2.2. For V1.4 and V2.0, change the instructions at 19B and 19E
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to the following:
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019B sta fe4
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019E sta 10ee
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Make a back-up copy of DDT.COM before you use DDT to make the
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following changes:
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A>ddt ddt.com
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DDT VERS 2.2
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NEXT PC
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1400 0100
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-l103
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103 JMP 013D
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.
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.
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.
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-a103
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0103 jmp 18b
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-a18b
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018B lhld 1ec
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018E shld 8e7
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0191 inx h
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0192 shld 8ed
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0195 lda 1eb
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0198 sta ad5
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1
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CP/M V2.2 Application Note 07
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019B sta fea
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019E sta 10f4
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01A1 jmp 13d
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- s1ec
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01EB ?? f7
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01EC ?? 30
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01ED ?? 00
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01EE ?? .
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-g0
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A>save 19 ddt6.com
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To change the restart number for DDT in the future, modify only
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the 3 bytes 1EBH, 1ECH and 1EDH.
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Licensed users are granted the right to include these
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modifications in CP/M software.
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