---
title: "ZX80 Prestel Model"
id: 76688
type: "computer_media"
slug: "zx80-prestel-model"
url: "http://localhost/computer_media/zx80-prestel-model/"
markdown_url: "http://localhost/computer_media/zx80-prestel-model.md"
published_at: "2026-11-11T08:02:13+00:00"
modified_at: "2026-11-11T08:02:13+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2026/11/zx80-prestel-model-1.png"
excerpt: "A ZX80 imitation of the British Prestel viewdata service: pick numbered pages from an index, as on a teletext screen."
post_tag:
  - name: "Downloadable"
    slug: "downloadable"
    taxonomy: "post_tag"
    url: "http://localhost/tag/downloadable/"
  - name: "ZX80"
    slug: "zx80"
    taxonomy: "post_tag"
    url: "http://localhost/tag/zx80/"
model:
  - name: "Sinclair ZX80"
    slug: "zx80"
    taxonomy: "model"
    url: "http://localhost/model/zx80/"
genre:
  - name: "Demo"
    slug: "demo"
    taxonomy: "genre"
    url: "http://localhost/type/demo/"
media_type: "Program"
download_url: "https://archive.org/download/timex-sinclair-software-archive/ZX80%20Prestel%20Model%20%281981%29%28-%29%28ZX80%29%28GB%29%28Program%29.zip"
mediadate: "1981"
images:
  - url: "http://localhost/wp-content/uploads/2026/11/zx80-prestel-model-1.png"
  - url: "http://localhost/wp-content/uploads/2026/11/zx80-prestel-model-2.png"
article_media:
  - id: 19735
    title: "ZX80 Prestel Model"
    type: "article"
    url: "http://localhost/article/zx80-prestel-model/"
media_type_tags: "Demo"
license: false
---

# ZX80 Prestel Model

A model of Prestel, the British Post Office’s viewdata service, reprinted by Syntax from the newsletter of EZUG, a UK ZX80 users’ group. RUN shows an index of numbered choices; choosing 1 leads to a sub-index and pages 11 to 13 with short notes on electricity (USE V=IR and so on), each ending with N/L TO RETURN TO INDEX. Choices 2 to 4 are placeholders for pages you add yourself, and 0 stops the program.

As printed, choice 4 runs into the STOP in line 4990 instead of returning to the index. It fits in 1K.

Published in Syntax June 1981 ([ZX80 Prestel Model](https://timexsinclair.com/article/zx80-prestel-model/)).

## Source Code

```
  10 LET A=0
  20 GO SUB 5000
  30 LET A$= "TYPE NUMBER NEEDED"
  40 PRINT A$
  50 GO SUB 5100
  60 PRINT "1. V, I, R"
  70 PRINT "2. CIRCUIT EQUATION"
  80 PRINT "3. POWER"
  90 PRINT "4. RESISTORS"
 100 GO SUB 5100
 110 PRINT "OR TYPE 0 TO STOP"
 120 INPUT B
 130 CLS
 140 IF B=0 THEN STOP
 150 IF B<0 OR B>4 THEN GO TO 10
 160 GO TO B*1000
1000 LET A=1
1010 GO SUB 5100
1020 PRINT A$
1030 GO SUB 5100
1040 PRINT "1. TO GET V"
1050 PRINT "2. TO GET I"
1060 PRINT "3. TO GET R"
1070 GO SUB 5100
1080 INPUT B
1090 CLS
1100 IF B<1 OR B>3 THEN GO TO 1000
1110 GO TO 1100+B*100
1200 LET A=11
1210 GO SUB 5000
1220 PRINT "USE V=IR"
1230 GO SUB 5200
1300 LET A=12
1310 GO SUB 5000
1320 PRINT "USE I=V/R"
1330 GO SUB 5200
1400 LET A=13
1410 GO SUB 5000
1420 PRINT "USE R=V/I"
1430 GO SUB 5200
2000 PRINT 2000
2010 GO SUB 5200
3000 PRINT 3000
3010 GO SUB 5200
4000 PRINT 4000
4990 STOP
5000 FOR C=2 TO 11
5010 PRINT " ";
5020 NEXT C
5030 PRINT "PAGE ";A
5040 GO SUB 5100
5050 RETURN
5100 FOR C=1 TO 3
5110 PRINT
5120 NEXT C
5130 RETURN
5200 GO SUB 5100
5210 PRINT "N/L TO RETURN TO INDEX"
5220 INPUT C$
5230 CLS
5240 GO TO 10
5250 RETURN
```