--- title: "Program Printout: London Bridge" type: "article" slug: "program-printout-london-bridge" url: "http://localhost/article/program-printout-london-bridge/" markdown_url: "http://localhost/article/program-printout-london-bridge.md" published_at: "2020-10-27T17:09:13+00:00" modified_at: "2026-06-21T23:26:28+00:00" featured_image: url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg" excerpt: "Most computer games require nothing except a quick finger on the cursor key. Most of the rest, those which require a bit of brain power, are adaptations of games when the word computer meant a person with an abacus. London Bridge is one of the few routines we have seen which is original, was written…" category: - name: "Timex Sinclair User" slug: "timex-sinclair-user" taxonomy: "category" url: "http://localhost/category/periodicals/timex-sinclair-user/" post_tag: - name: "1983" slug: "year-1983" taxonomy: "post_tag" url: "http://localhost/tag/year-1983/" - name: "Downloadable" slug: "downloadable" taxonomy: "post_tag" url: "http://localhost/tag/downloadable/" - name: "Full Text" slug: "fulltext" taxonomy: "post_tag" url: "http://localhost/tag/fulltext/" - name: "TS 1000" slug: "ts1000" taxonomy: "post_tag" url: "http://localhost/tag/ts1000/" - name: "Type-in program" slug: "type-in-program" taxonomy: "post_tag" url: "http://localhost/tag/type-in-program/" model: - name: "Timex/Sinclair 1000" slug: "ts-1000" taxonomy: "model" url: "http://localhost/model/ts-1000/" publication: "Timex Sinclair User" publication_r: id: 10278 title: "Timex Sinclair User" type: "periodical" url: "http://localhost/periodical/timex-sinclair-user/" volume: "1" issue: "1" issues_articles: - id: 26866 title: "Timex Sinclair User n1" type: "issue" url: "http://localhost/issue/timex-sinclair-user-n1/" pages: "34" pubdate: "June 1983" archive_link: false volumeissue: "v1n1" article_media: - id: 57344 title: "London Bridge" type: "computer_media" url: "http://localhost/computer_media/london-bridge/" --- # Program Printout: London Bridge Most computer games require nothing except a quick finger on the cursor key. Most of the rest, those which require a bit of brain power, are adaptations of games when the word computer meant a person with an abacus. London Bridge is one of the few routines we have seen which is original, was written for the computer, and which calls for nerve, thought and luck. The display consists of a graphic representation of the bridge, seen from above, with the roadway made up of a random mix of the quire nothing except a quick finger on the cursor key. Most of the rest, those which require a bit of brain power, are adaptations of games when the word computer meant a person with an abacus. London Bridge is one of the few routines we have seen which is original, was written for the computer, and which calls for nerve, thought and luck. The display consists of a graphic representation of the bridge, seen from above, with the roadway made up of a random mix of the numbers 1 to 5, representing five types of flagstone. You are required to cross to the other bank but, as you would expect, London Bridge is falling down. The computer will give you a number, perhaps 4. That tells you that one of the type 4 stones is about to fall into the river. In selecting your next move, therefore, you can gamble by moving onto a 4 or play safe by selecting a different number. The player enters his move by following the nine-number grid displayed under “INPUT” in the bottom left of the screen; 7, for example, will move you left and down and 2 will send you backwards. Invalid moves are ignored. You score 10, 20 or 50 points respectively for each move forwards, sideways or backwards, but taking risks trebles those scores and a high score is necessary to beat the world record of 1,700. Beware — don’t dally too long at the start of the bridge — you may be cut off by successive collapses, and don’t shillyshally near the south bank because that is where the bridge is weakest. We were impressed by the program and scored 1,900 after 12 attempts. ## Source Code: London Bridge ``` 1 REM "LONDON BRIDGE" 3 CLS 5 FAST 10 RAND 0 20 DIM A(66) 30 PRINT AT 2,9;"LONDON BRIDGE" 35 PRINT AT 3,8;"X-------------X" 40 LET WR=1700 50 PRINT AT 16,25;"WR=";WR;TAB 11;"## ##";TAB 0;"INPUT";TAB 1;"123";TAB 1;"4%56";TAB 1;"789" 55 PRINT AT 6,11;"#### % ####" 60 FOR I=1 TO 11 70 PRINT TAB 12;"## ##" 80 NEXT I 90 FOR N=11 TO 60 100 LET A(N)=INT (RND*5+1) 110 LET A$=CHR$ (28+A(N)) 120 LET M=(N-1)/5 130 GOSUB 500 135 NEXT N 140 LET N=8 145 SLOW 150 LET A(N)=-28 155 PRINT AT 20,20;"TO COLLAPSE" 160 LET DROP=INT (RND*(67-N)+N-6) 170 IF A(DROP)<=0 THEN GOTO 160 180 PRINT TAB 25;A(DROP) 190 INPUT DIR 200 LET I=(INT DIR-1)/3 205 LET M=(N-1)/5 210 LET J=M-INT M+I-INT I 220 LET N1=N+5*(INT I-1)+3*(I-INT I)-1 230 IF DIR<1 OR DIR>9 OR J<0.1 OR J>1.4 OR N1<6 THEN GOTO 190 235 IF A(N1)<=0 AND N1<=60 THEN GOTO 190 240 IF N1>60 THEN LET A(N1)=-28 250 LET A$=CHR$ (28+A(N)) 260 GOSUB 500 270 LET M=(N1-1)/5 280 LET A$=CHR$ (156+A(N1)) 290 GOSUB 500 300 PRINT AT 20,20;" ";TAB 25;" " 310 FOR J=1 TO 70 320 NEXT J 330 LET M=(DROP-1)/5 350 LET A$=" " 360 GOSUB 500 370 IF N1=DROP THEN GOTO 600 380 IF N1>60 THEN GOTO 800 390 LET SCORE=10*(3-INT I)+10*(2-INT I)*(1-INT I) 400 IF A(N1)=A(DROP) THEN LET SCORE=SCORE*3 410 GOSUB 900 420 LET A(DROP)=0 430 LET N=N1 440 GOTO 155 500 PRINT AT 5+INT M,13+5*(M-INT M);A$ 510 RETURN 600 PRINT AT 20,16;"YOU HAVE FALLEN";TAB 18;"IN THE WATER" 650 PRINT AT 0,0;"%A%N%O%T%H%E%R% %T%R%Y%?%? (1=YES/0=NO)" 655 INPUT CHO 657 GOSUB 7000 660 IF CHO<0 OR CHO>1 THEN GOTO 655 668 IF CHO=1 THEN CLS 670 IF CHO=1 THEN RUN 680 IF CHO=0 THEN GOSUB 6000 800 LET SCORE=1000 810 GOSUB 900 811 PRINT AT 0,0;"%A%N%O%T%H%E%R% %T%R%Y%?%? (1=YES/0=NO)" 813 INPUT CHO 814 GOSUB 7000 815 IF CHO<0 OR CHO>1 THEN GOTO 813 817 IF CHO=1 THEN CLS 818 IF CHO=1 THEN RUN 819 IF CHO=0 THEN GOSUB 6000 900 LET A(1)=A(1)+SCORE 910 PRINT AT 11,22;"SCORE ";SCORE;" " 920 PRINT AT 13,22;"TOTAL ";A(1) 930 RETURN 6000 GOSUB 7000 6020 CLS 6030 PRINT AT 11,10;"%T%H%A%N%K% %Y%O%U" 6050 GOSUB 7000 6060 PRINT AT 11,9;"%C%O%M%E% %A%G%A%I%N" 6070 GOSUB 7000 6090 CLS 6100 STOP 7000 FOR Z=1 TO 30 7003 NEXT Z 7005 RETURN 7500 STOP 7510 CLEAR 7520 SAVE "1019%2" 7530 RUN ```