I have found that on page 68, listing 5.2 (the pitch generator) is missing three procedure definitions: PROCAlterPit;
PROCFinalTimeCheck, and; PROCOvertime. The listing just ends at line 2350, in both the 1983 PDF on 8bs, and the 1984 version on archive.org.
The text under
Program notes on page 70 refers to various lines ranging from 2490-2590, as well as referring to PROCAlterPit, PROCFinalTimeCheck, and; PROCOvertime, so clearly a number of lines are missing and the listing is truncated.
The saved copy of the listing is in file "PG5-2" in the
making_music.zip file containing the DSD of the code. This saved copy is similarly incorrect, ending prematurely at line 2350.
In fact, the DSD version introduces another error, as it has changed line 2330 from caling PROCAlterPit to calling PROCAlter instead, which while it exists, is incorrect and is not a substitute for PROCAlterPit (even though they work similarly, but on amplitude and pitch respectively). As a side note, whist PitfallJones should be applauded for their work on the DSD image, it would be a good idea for the link to making_music.zip to be removed, the saved listing of 5.2 to be corrected, and then have the zIp file of DSD re-uploaded, as it is not a good idea to have incorrect source code floating around on the web (as it can cause endless headaches).
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However, the missing lines can be found in a complete listing for program 5.2, on SIDE0.SSD which is included with the OCR scanned PDF on
8bs.com - Publications. The missing lines 2360-2670 are as follows:
Code: Select all
2360
2370 DEF PROCAlterPit
2380 INPUT NewVal$:PRINTTAB(0,2)SPC(6)
2390 IF NewVal$="" PROCReset: PROCPrintEnv:ENDPROC
2400 NewVal=EVAL(NewVal$)
2410 PRINTTAB(30,0)SPC(20)
2420 ON (Input-32) GOTO 2430,2440,2450,2460,2470,2480
2430 PI1=NewVal:ENDPROC
2440 PI2=NewVal:ENDPROC
2450 PI3=NewVal:ENDPROC
2460 PN1=NewVal:ENDPROC
2470 PN2=NewVal:ENDPROC
2480 PN3=NewVal:ENDPROC
2490 ENDPROC
2500
2510 DEF PROCPitchEnv
2520 Time=0
2530 YScale=3
2540 MOVE 0,Pitch*YScale
2550 REPEAT
2560 Pitch=Pit1
2570 PROCP(PI1, PN1)
2580 PROCP(PI2, PN2)
2590 PROCP(PI3, PN3)
2600 UNTIL FTime OR T1>127
2610 ENDPROC
2620
2630 DEF PROCFinalTimeCheck
2640 FTime=FALSE
2650 IF Time>Duration*5 Time=Duration*5:FTime=TRUE
2660 ENDPROC
2670
Nevertheless, these lines
also contain an error, which can be fixed with these two lines:
Code: Select all
2420 ON (Input-32) GOTO 2430,2440,2450,2460,2470,2480,2485
2485 Pit1=NewVal:ENDPROC
Note that the OCR scanned PDF, on 8bs.com, also has two addtional OCR induced errors, which are fixed with these two lines:
Code: Select all
150 IF Input$="C" PROCAxis:PROCAxis2
2310 IF Input=39 p=1
These two lines are displayed correctly in the bitmap scanned PDF on
archive.org.
In fact, it has to be said that the "digitally remastered" OCR scanned PDF on 8bs.com is literally
riddled with OCR induced errors/typos, and that almost every line should be taken with a pinch of salt... or least cross-checked with the bitmap scan of the later copy on archive.org.
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FWIW, and for full disclosure, I have also written about this omission in my blog,
Making music on the BBC computer - Errata. I have also uploaded the correct listings, and missing lines, from the book to Github:
greenonline/
Making-music-on-the-BBC-computer
