---
title: "Isolation"
id: 72839
type: "computer_media"
slug: "isolation"
url: "http://localhost/computer_media/isolation/"
markdown_url: "http://localhost/computer_media/isolation.md"
published_at: "2026-10-27T15:54:36+00:00"
modified_at: "2026-10-27T15:54:36+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2026/10/h-0.png"
excerpt: "Trap the computer's pieces on a 7×7 board: each turn you remove a square and the computer claims one, and you score for every piece left with no free neighbour."
post_tag:
  - name: "Downloadable"
    slug: "downloadable"
    taxonomy: "post_tag"
    url: "http://localhost/tag/downloadable/"
  - name: "TS 2068"
    slug: "ts2068"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts2068/"
model:
  - name: "Timex/Sinclair 2068"
    slug: "ts-2068"
    taxonomy: "model"
    url: "http://localhost/model/ts-2068/"
indiv:
  - name: "Drew Nisbet"
    slug: "drew-nisbet"
    taxonomy: "indiv"
    url: "http://localhost/indiv/drew-nisbet/"
genre:
  - name: "Strategy"
    slug: "strategy"
    taxonomy: "genre"
    url: "http://localhost/type/strategy/"
media_type: "Program"
programmers:
  - name: "Drew Nisbet"
    slug: "drew-nisbet"
    taxonomy: "indiv"
    url: "http://localhost/indiv/drew-nisbet/"
download_url: "https://archive.org/download/timex-sinclair-software-archive/Isolation%20%281982%29%28Nisbet%2C%20Drew%29%28TS2068%29%28US%29%28Program%29.zip"
tsrun_member: "Isolation (1982)(Nisbet, Drew)(TS2068)(US)(Program)/Isolation (1982)(Nisbet, Drew)(TS2068)(US)(Program).tap"
mediadate: "1982"
images:
  - url: "http://localhost/wp-content/uploads/2026/10/h-0.png"
  - url: "http://localhost/wp-content/uploads/2026/10/h-3.png"
article_media:
  - id: 24334
    title: "Isolation"
    type: "article"
    url: "http://localhost/article/isolation/"
media_type_tags: "Strategy"
license: false
---

# Isolation

Isolation is played on a 7×7 board of `+` squares, rows A–G and columns 1–7. You type a letter and then a number to knock out a square; the computer then marks one of its own, though now and then you get a second move first. When you enter a number instead of a letter the game ends and you score a point for every computer square completely surrounded by knocked-out squares or the edge.

The program is the type-in from SYNC v2 n2 (1982) (see the article Isolation). Bob Swoger’s copy was transferred from the TS1000 to the TS2068 with Upload 2000.

## Program Analysis

The board is held in `DIM A(81)`, a 9×9 array whose outer ring is preset to 1 so that neighbour tests never fall off the edge. Line 500 counts the computer’s squares whose eight neighbours are all taken.

### Notable Techniques

- A border of filled cells around the 7×7 board removes all edge checks from the scoring loop.

This copy came from a Larken disk. The disk copy still POKEd the ZX81 display file, so line 391 now prints the square with `PRINT AT` (the computer’s mark is a checkered graphic), caps lock is set at the start, and any number now ends the game as the instructions say. Tested in ZEsarUX on a stock TS2068.

## Source Code

```
    1 REM ISOLATION
    2 PAPER 7: INK 0: BORDER 7: CLS : POKE 23658,8: FOR i=0 TO 7: POKE USR "a"+i,170-85*(i-2*INT (i/2)): NEXT i
   10 REM ?? 
   20 DIM A(81)
   30 LET T=0
   40 LET S=0
   45 FOR I=1 TO 81
   50 IF I<=10 OR I=18 OR I=19 OR I=27 OR I=28 OR I=36 OR I=37 OR I=45 OR I=46 OR I=54 OR I=55 OR I=63 OR I=64 OR I>=72 THEN LET A(I)=1
   60 NEXT I
   70 FOR I=1 TO 7
   80 PRINT "::::";
   90 FOR J=1 TO 7
  100 PRINT "+";
  110 NEXT J
  120 PRINT "";CHR$ (I+64);""
  130 NEXT I
  150 PRINT "::::1234567::"
  160 PRINT "::::::::::::::::::::"
  162 PRINT AT 0,11;"ENTER A LETTER FIRST"
  164 PRINT AT 1,11;"THEN A NUMBER. TO "
  166 PRINT AT 2,11;"STOP ENTER A NUMBER"
  167 PRINT AT 3,11;"LARGER THAN 7."
  168 PRINT 
  170 REM ?? 
  180 LET D=INT (RND*61)+11
  190 IF A(D)>0 THEN GO TO 180
  200 LET A(D)=2
  210 LET Y=INT (D/9)
  220 LET X=D-9*Y-1
  230 LET M=9
  240 GO SUB 380
  250 INPUT Y$
  260 INPUT X$
  270 LET Y=(CODE (Y$))-64
  280 IF Y<1 THEN GO TO 480
  290 LET X=(CODE (X$))-48
  300 IF Y>7 OR X>7 THEN GO TO 250
  310 LET C=9*Y+X+1
  320 IF A(C)>0 THEN GO TO 250
  330 LET A(C)=1
  340 LET M=0
  350 GO SUB 380
  360 IF INT (RND*5)=2 THEN GO TO 250
  370 GO TO 180
  380 LET P=X+2+33*(Y-1)
  390 REM POKE PEEK (16396)+256*PEEK (16397)+P,M
  391 PRINT AT Y-1,X+1;CHR$ (32+112*(M=9))
  400 LET T=T+1
  410 IF T=49 THEN GO TO 480
  420 IF T=16 THEN PRINT AT 12,2;"HOW ARE YOU DOING ?"
  430 IF T=28 THEN PRINT AT 12,2;"YOU AREN'T TRYING!"
  440 IF T=40 THEN PRINT AT 12,2;"WHATS THE MATTER?"
  450 IF T=40 THEN PRINT AT 13,0;"THE COMPUTER RUNNING CIRCLES"
  460 IF T=40 THEN PRINT AT 14,8;"AROUND YOU?"
  470 RETURN 
  480 FOR I=11 TO 71
  490 REM ?? 
  500 IF A(I)=2 AND A(I-10)=1 AND A(I-9)=1 AND A(I-8)=1 AND A(I-1)=1 AND A(I+1)=1 AND A(I+8)=1 AND A(I+9)=1 AND A(I+10)=1 THEN LET S=S+1
  510 NEXT I
  520 PRINT "POINTS= ";S
  530 STOP 
  540 GO TO 10
 8200 REM  removed (LKDOS-only)
 8391 REM  removed (LKDOS-only)
 8400 REM  removed (LKDOS-only)
 8410 REM  removed (LKDOS-only)
 9989 REM  removed (LKDOS-only)
 9992 SAVE "ISOLAT.B1" LINE 1
 9998 REM  was LKDOS-only
```