(Insert, yet again, my “the VIC-20 was my first computer” story here.)

When I got my VIC-20, that is all I had — just the VIC-20 computer. I did not have the Commodore Datasette (tape recorder). I could not save anything that I typed in. Because of this, I recall leaving my VIC turned on just so I wouldn’t lose the program I had typed in (or was in the process of typing in).

I am not 100% sure which manual came with my early model VIC, but it probably was the “Personal Computing on the VIC-20: a friendly computer guide.” At least, things inside this PDF look familiar.

In the back of the book is a section called “Programs to Try.” It contains listings of three games. In the PDF above, these games where called:

• Tank Versus UFO by D. Later
• Killer Comet by Duane Later
• Rocket Command by Duane Later

But, in the book that came with my VIC-20, I believe at least two of them were called something else: Meteor and Rocket Fighter! I am pretty sure I remember Tank versus UFO being called that in my book.

I recall typing these programs in and fixing either bugs in the listing or, more likely, bugs in my typing ability. Much to my surprise, I found my original VIC-20 tapes several years ago and was able to get “most” of what I had on those tapes loaded in to an emulator. Two of the programs I found were ones I had typed in from the VIC-20 book.

When I went to look up these games, I found many videos on YouTube showing different versions than the ones I had. I originally figured some VIC owners just customized the games and they ended up in a collection somewhere on the Internet.

But now I think there might have been multiple versions of these games released by Commodore. The PDF of the book on archive.org says it is the 5th edition. I am now trying to find out how many editions of this book were published. I would like to see if they contain different versions of these programs.

Here are some differences I found between the ones I typed in from my book, and the ones shown in that 5th edition copy I found online.

Killer Comet (PDF) versus Meteor (mine)

The differences between the two versions are mostly cosmetic:

• The name: “Meteor” in my book, and “Killer Comet” in the PDF.
• The “graphics”: A block for the cannon and ball for the bullet in the PDF, versus a letter “A” for the cannon and vertical bar for the bullet in mine.
• Game messages: “Delta base destroyed” in my book, versus “Moon base destroyed” in the PDF. Strangely enough, the “Killer Comet” prints “Meteor destroyed.” This further makes me think I had an earlier version and Meteor was the original name.
• Stars on the screen (I may have added those) done through some extra POKEs neat the top of the program:

4 POKE7910,46:POKE8140,46:POKE8170,46:POKE8000,46:POKE7809,46:POKE7715,46:POKE7998,46
5 POKE7812,46:POKE7949,46:POKE8020,46:POKE7777,46:POKE7944,46:POKE8005,46:POKE7793,46
8 POKE8179,1

Thanks to a VIC-20 memory map at zimmers.net, I can see that all of these locations are in screen memory:

7680-8191     Screen memory

The 46 is a period. These POKEs are poking the “stars” in the background. As the meteor goes across the screen, it will erase those stars, so I am not sure if this was part of the original program, or something I had added. I know I had a game I was writing that did a similar thing with stars in the background, but mine got restored so they were not erased by other objects:

If I added those stars, perhaps I also changed the name? But if so, it wouldn’t explain why the Killer “Comet” version still calls it a meteor…

Rocket Command (PDF) versus Rocket Fighter (mine)

Again, these versions are very similar except for a few minor differences:

• The name: “Rocket Fighter” in my book, versus “Rocket Command” in the PDF.
• The “graphics”: Different ASCII (er, PETSCII) characters are used for the game playfield. The PDF uses a letter “X”, and mine used a PETSCII graphics character. For the missile, the original used a text up arrow, and mine uses a card clubs character.

Tank versus UFO

If I saved out Tank versus UFO, I couldn’t find it. Or, it might have been damaged on the ancient cassette tapes I found a few years ago and I couldn’t get it to load. I have no idea what differences there might be between the 5th edition version and whatever I typed in.

Why so different?

When I look up these games on YouTube, I see videos several other variations. I expect some where enhancements done by VIC-20 owners, but others look like just slightly updated versions. Did I do the same thing, and modify these programs to change the names?

Doing some web searching, I found this reference:

Modified versions of Tank-v-Ufo (p. 153-156) appear to have been published as Tank-v-Ufo (VIC Games), Tank Attack (Commodore Computing International, 82-11), Ufo-Jagd (Happy Computer, 83-12), Invasion (Commander, 84-02) and Save The City! (Big K, 84-04).

A slightly different version of Rocket Command (p. 158-159) was published in VIC! (Vol 6).

Modified versions of Rocket Command (p. 158-159) appear to have been published as UFO Target (Commodore Computing International, 83-08) and Rocket! (Big K, 84-04).

– http://www.vic20listings.freeolamail.com/book_userguide.html

And none of those match the names of the versions I have! It does “confirm” that Commodore published different versions of at least two of these – Tank Attack (Tank vs. UFO) and Rocket Command (UFO Target).

Tank vs UFO versions

Tank Attack (Commodore Computing International)

Yet the title screen still reads “Tank versus UFO”…

Invasion (Commander … magazine?)

Save the City (Big K)

Yet the title still reads “Tank versus UFO”…

Rocket Command versions

UFO Target (Commodore Computing International)

Rocket Command

I find this version interesting because it has the PETSCII “X” character used for the base, like my version, but still uses the up arrow character like the PDF version.

Rocket (Big K)

Yet the title still reads “Rocket Command”.

It is clear that games based on the type-in programs were certainly appearing in may publications… Did the version I have actually come from a magazine, rather than the VIC-20 manual? (I remember having Family Computing and Compute, which spun off in to Compute’s Gazette, during my VIC-20 days.)

Can anyone shed some light on this? How many editions to this manual were there, and did the program listings change? I did find a 1981 manual that does not say what edition it is, so it might be the first edition — but the program listings have the same names as the 5th edition.

I’d really like to know where I got “Meteor” and “Rocket Fighter” from.

To be continued…

Rocket Fighter program listing

!--------------------------------------------------
!- April 8, 2020 10:01:03 PM
!- Import of : 
!- w:\vicconversions\vicrocket\rocket fighter.prg
!- Unexpanded VIC20 / C16 / Plus4
!--------------------------------------------------
2 REM ROCKET FIGHTER
10 VI=9*16^3:OF=38400-7680:PRINT"{clear}"
11 FORA=38400+22TO38400+22*23:POKEA,0:NEXT
15 C=7680+22*20+15
20 POKEVI+15,6+128+64+32+8
30 PRINT"{home}{red}*** rocket fighter ***";
35 PRINT"{space*5}hit any key"
40 PRINT"{down*14}{black}V{left}{down}V{left}{down}V{left}{down}V{left}{down}V{left}{down}V{left}{down}VVVVVVVVVVVVVVVV";
50 PRINT"{up}{left*14}XXXXXXXXXXXXXX"
60 A=7680+22*22+15
70 GETA$:IFA$<>""ANDB=0THENB=1:POKEC+22,32:D=C:C=C-1:K=1:POKE9*16^3+13,128+125:L=16
71 IFK=1THENL=L-1:POKE9*16^3+14,L
72 IFL=0THENK=0:POKE9*16^3+13,0
75 IFC=8121THENPRINT"{home}{down*6} no more rockets !!!":POKE9*16^3+14,0:FORAA=1TO3000:NEXT:RUN
80 IFB=0THEN110
85 POKED,32:D=D-22
90 IFPEEK(D)=60ORPEEK(D)=62THENGOSUB500:GOTO70
100 IFD<7680+88THENB=0:GOTO110
105 POKED,88
110 IFH=0THEN200
115 IFH=0THEN70
120 POKEF,32:F=F+E
125 IFF=ITHENH=0:GOTO70
130 IFPEEK(F)=30THENGOSUB500:GOTO70
140 POKEF,G:GOTO70
200 H=1
205 IFINT(RND(1)*2)=1THENE=-1:F=7702+(INT(RND(1)*10)+6)*22:I=F-22:G=60:GOTO115
210 E=1:F=7680+(INT(RND(1)*10)+6)*22:I=F+22:G=62:GOTO115
500 B=0:H=0
501 SC=SC+10:PRINT"{home}{down*3}{purple}score="SC
502 POKEF+OF,4:POKEF+1+OF,4:POKEF-1+OF,4
503 POKEF+OF+22,4:POKEF-22+OF,4
510 POKEF,102:POKEF+1,42:POKEF-1,42:POKEF+22,42:POKEF-22,42
521 POKE9*16^3+13,128+35
522 FORY=16TO0STEP-1
523 POKE9*16^3+14,Y
524 FORP=1TO10:NEXT:NEXT
530 POKEF,32:POKEF+1,32:POKEF-1,32:POKEF+22,32:POKEF-22,32
531 POKEF+OF,0:POKEF+1+OF,0:POKEF-1+OF,0
532 POKEF+OF+22,0:POKEF-22+OF,0
533 POKE9*16^3+13,0
540 FORGH=FTOF+22*16STEP22
544 II=PEEK(GH):POKEGH,G:FOROO=1TO50:NEXT
546 POKEGH,II:NEXT
800 RETURN
999 GOTO70
1000 POKE9*16^3+13,128+125
1001 FORY=16TO0STEP-1
1005 POKE9*16^3+14,Y
1010 NEXT:POKE9*16^3+13,0
1020 RETURN

Meteor program listing

!--------------------------------------------------
!- April 8, 2020 10:00:20 PM
!- Import of : 
!- w:\vicconversions\vicrocket\meteor.prg
!- Unexpanded VIC20 / C16 / Plus4
!--------------------------------------------------
1 C=7680+22*6:DIMB(12):LL=C:POKE9*16^3+15,8
2 PRINT"{yellow}{clear}******* meteor *******":T=0
3 PRINT"{space*5}hit any key"
4 POKE7910,46:POKE8140,46:POKE8170,46:POKE8000,46:POKE7809,46:POKE7715,46:POKE7998,46
5 POKE7812,46:POKE7949,46:POKE8020,46:POKE7777,46:POKE7944,46:POKE8005,46:POKE7793,46
8 POKE8179,1
9 FORA=38444TO38400+505:POKEA,1:NEXT
10 :
20 FORA=1TO12:B(A)=160:NEXT
21 IFW=0THEN25
22 POKE9*16^3+14,U:U=U-2:IFU<=0THENW=0:POKE9*16^3+13,0
25 F=1
26 FORE=0TO44STEP22
27 FORD=C+ETOC+3+E:POKED,32:F=F+1:NEXT:NEXT
28 C=C+1
29 F=1
30 POKE8179,1:FORE=0TO44STEP22
35 FORD=C+ETOC+3+E:POKED,B(F):F=F+1:NEXT:NEXT
36 IFPEEK(8178)=1THENPRINT"{clear}{down*5}delta base destroyed!":GOTO500
40 GETA$:IFA$<>""ANDG=0THENG=1:S=7680+15+22*21
50 IFG=0THEN80
55 POKES,32:S=S-22
60 IFS<7746THENG=0:GOTO21
70 IFPEEK(S)=160THENPOKES,32:G=0:T=T+1:W=1:POKE9*16^3+13,128+000:U=15:GOTO80
71 IFPEEK(S-1)=160THENG=0:POKES-1,32:T=T+1:W=1:POKE9*16^3+13,128+000:U=15:GOTO80
75 POKES,93
80 F=1
81 IFT=12THENPRINT"{clear}{down*5}***meteor destroyed***":FORR=1TO2500:NEXT:LL=LL+44:C=LL:GOTO2
82 FORE=0TO44STEP22
84 FORD=C+ETOC+3+E:IFPEEK(D)=32THENB(F)=32
86 F=F+1:NEXT:NEXT
90 GOTO21
500 POKE9*16^3+13,128+5
505 POKE9*16^3+14,5:FORR=1TO300:NEXT
510 FORA=15TO0STEP-1
511 POKE9*16^3+14,A
520 FORRR=1TO500:NEXT
530 NEXT
540 FORRR=1TO2000:NEXT:RUN