viCOMMODORE
64 FUNANDGAMESVolume 2


anything wrong. First, it first checks the crucialeliminatingthe proof numbersmakes the
numbers on line 999. Next, it checks the maincopyright notice and version date easier to
BASIC section for erors. If everything looksread. However, you do need to type lines 3-10
good, it reads a DATAline and checks it. If a DATAso the proof number and line count for the en-
line is bad, it stops and reports the bad line.tire programwil check corectly with the
Finaly, it counts the number of DATAlines, andnumbers shown at the end ofthe listings in the
complains if there are too few or too many. Albook.
this checking takes afew seconds, but it's worth
it, since PROOF-IT must be corect so it canUsing "P" to Check a Whole Program
accurately check al the programsyou type
from the book.
Since geting PROOF-IT and the "StandardIn addition to showing the proof number for
Framework"corect is so vital, you can geteach line, PROOF-IT can also check an entire
these important programs on disk or tape for aprogram to see that you have typed the right
nominalcharge.See the section Obtainingnumber of lines, and the right line numbers.
Programs on Disk for details.With PROOF-IT active, if you type the com-
mand P on a line by itself, and pres RETURN,
PROOF-IT wil tel you the number of lines in
Using PROOF-ITthe program, and the proof number for al the
line numbersin the program.The corect
Once you've successfuly typed PROOF-IT,number of lines and program proof value are
SAVEd it on disk or tape, and it has RUN cor-printed at the end of each listing.
rectly, you are ready to type a program. IfyouIf the numbers shown by PROOF-IT when
are anxious to get started, you may want toyou press P (and RETURN)match the numbers
select one of the short QUICKprograms, sinceat the end of the listing, you have typed al the
you don't have to type the standard frameworklines, and they al have the corect line num-
first. If you type anything other than one of thebers. Should the proof numbers not match,
QUICK programs, your next step is to type theyou'l know whether to look for either mising
standard framework (see listing on page xv,)or extra lines. (Hint: did you forget to include
and SAVE it for future use..the standard framework?) PROOF-IT doesn't
Ifyou are typing one ofthe QUICKprograms,tel you which lines are missing or extra, but I
first LOAD the PROOF-ITprogram and RUN it.you can list the program a screen at a time and
When it says "READY," type the first line fromcheck just the line numbers against the book.
the listing you have selected. When you pressThe P command checks al the line numbers
RETURN,check the proof number on the screenin the program, but does not check the rest of
with the number printed at the end ofeach linethe program. The line-by-line proof numbers
in this book.are your assurance that each line is corect,
At the end of each program line in the bookwhile the P values tel you that you typed the
the proof number is shown as a REMarkstate-right number of lines, and that you got al the
ment. For example, in this line,line numbers corect.
Youcan go back and check previous lines at
150 PRINT-HELLO-:rem 6470any time with PROOF-IT,without retyping the
line. LIST the line or lines you want to check,
and use the cursor keys to put the cursor any-
the part" :rem 6470" is the proof number. Dowhere on the line you want to check. When you
not include the trailing colon, "rem" and proofpress RETURN,the proof number for that line
number when you type a line, since they are notwil be shown.
part of the program. When the proof numberRemember,PROOF-IT calculatesa proof
shown on the screen matches the number in thenumber for each line and prints it on the screen.
book, the line has been typed corectly. If theBut it's up to you to check that number against
proof numbers difer, check the line carefuly,the corect proof value printed at the end of
corect the eror, press RETURNagain, and theneach line in the book. If you have trouble get-
again check the proof number on your screenting a program to work, LIST it in groups of
with the proof number shown in the listing.about 15lines, move the cursor to each line and
Lines 3-10 in the program listings do notpressRETURN. Check each proofnumber
have proof numbers in the book. Those linesagainst the number in the book. (It helps to
don'tchange how the programruns,andhave a partner, so one person works the C-64

