---
title: "Bases"
id: 72976
type: "computer_media"
slug: "bases"
url: "http://localhost/computer_media/bases/"
markdown_url: "http://localhost/computer_media/bases.md"
published_at: "2026-10-27T21:30:09+00:00"
modified_at: "2026-10-27T21:30:09+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2026/10/bases-1.png"
excerpt: "Convert a number from any base between 2 and 36 to any other, checking each digit is valid for the base you gave."
post_tag:
  - name: "Downloadable"
    slug: "downloadable"
    taxonomy: "post_tag"
    url: "http://localhost/tag/downloadable/"
  - name: "QL"
    slug: "ql"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ql/"
model:
  - name: "Sinclair QL"
    slug: "sinclair-ql"
    taxonomy: "model"
    url: "http://localhost/model/sinclair-ql/"
indiv:
  - name: "Dilwyn Jones"
    slug: "dilwyn-jones"
    taxonomy: "indiv"
    url: "http://localhost/indiv/dilwyn-jones/"
genre:
  - name: "Mathematics"
    slug: "mathematics"
    taxonomy: "genre"
    url: "http://localhost/type/mathematics/"
media_type: "Diskette"
programmers:
  - name: "Dilwyn Jones"
    slug: "dilwyn-jones"
    taxonomy: "indiv"
    url: "http://localhost/indiv/dilwyn-jones/"
download_url: "https://archive.org/download/timex-sinclair-software-archive/Bases%20%281984%29%28Jones%2C%20Dilwyn%29%28Sinclair%20QL%29%28UK%29%28Program%29.zip"
mediadate: "1984"
images:
  - url: "http://localhost/wp-content/uploads/2026/10/bases-1.png"
media_type_tags: "Mathematics"
license: false
---

# Bases

Bases converts numbers between any two bases from 2 to 36. It asks for the base to convert from, the base to convert to and the value, prints the result and offers another conversion.

The REM reads “(C) Dilwyn Jones, 1984”. Its document file was lost from the disk image.

## Program Analysis

`CHECK` rejects characters that are not digits of the source base, and `CONVERT$` builds the result string.

It came from a QL owner’s floppy copies of QUANTA and IQLUG library material, imaged double-stepped so that only half of each disk survived; this file read back complete. The download holds the files exactly as recovered and a QL5A floppy image, *Bases.img*, with the same files and their QDOS headers. Mount the image as FLP1_ (drop it on the QLRun page, or use it as a floppy image in sQLux, QPC2 or Q-emuLator) and type `lrun flp1_BASES`.

Tested in QLRun with the JS ROM: 1985 in base 10 converted to binary.

## Source Code

```
100 REMark base to base conversion program
110 REMark --- (C)  Dilwyn Jones, 1984 ---
120 MODE 8:PAPER 0:WINDOW 512,256,0,0:CLS
130 WINDOW 452,220,30,16:BORDER 2,255
140 PAPER 6:INK 0:CSIZE 2,0
150 CLS:PAPER 0:INK 6:PRINT'       NUMBER BASE CONVERSIONS       ':PAPER 6:INK 0
160 WINDOW 444,206,34,28:CLS
170 REPeat program
180  CLS
190  REPeat loop2
200   REPeat loop
210    INPUT'Convert from base ';temp$
220    IF CHECK(temp$,10)=1 THEN EXIT loop
230   END REPeat loop
240   con_from=temp$
250   IF con_from>=2 AND con_from<=36 THEN EXIT loop2
260   PRINT'Error...base 2-36 only...'
270  END REPeat loop2
280  REPeat loop2
290   REPeat loop
300    INPUT'Convert  to  base ';temp$
310    IF CHECK(temp$,10)=1 THEN EXIT loop
320   END REPeat loop
330   con_to=temp$
340   IF con_to>=2 AND con_to<=36 THEN EXIT loop2
350   PRINT'Error...base 2-36 only...'
360  END REPeat loop2
370  REPeat loop
380   INPUT'Value:';a$
390   IF CHECK(a$,con_from)=1 THEN EXIT loop
400  END REPeat loop
410  PRINT'In Base ';con_to;' = ';CONVERT$(a$,con_from,con_to)
420  PRINT\'Any more (Y/N)?';
430  REPeat loop
440   k$=INKEY$(-1)
450   IF k$='y' THEN k$='Y'
460   IF k$='n' THEN k$='N'
470   IF k$='Y' OR k$='N' THEN PRINT k$:EXIT loop
480  END REPeat loop
490  IF k$='N' THEN EXIT program
500 END REPeat program
510 PRINT\'PROGRAM FINISHED.'
520 DEFine FuNction CHECK(num,base)
530  LOCal t$,valid,a
540  t$='0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'(1 TO base)
550  valid=1
560  FOR a=1 TO LEN(num)
570   IF (num(a) INSTR t$)=0 THEN valid=0
580  END FOR a
590  IF valid=0 THEN PRINT'Error...Invalid character...'
600  IF num='' THEN PRINT"Dont't be silly...":valid=0
610  RETurn valid
620 END DEFine CHECK
630 DEFine FuNction CONVERT$(num,from,tobase)
640  LOCal sum,num2$,char,digit,conv$,remn,loop
650  sum=0:num2$=num:conv$=''
660  FOR char=LEN(num2$) TO 1 STEP -1
670   digit=CODE(num2$(char))
680   sum=sum+(digit-48-7*(digit>=65)-32*(digit>=97))*(from^(LEN(num2$)-char))
690  END FOR char
700  REPeat loop
710   remn=INT(sum-(tobase*INT(sum/tobase))+.5)
720   sum=INT(sum/tobase)
730   conv$=CHR$(remn+48+7*(remn>9))&conv$
740   IF sum=0:EXIT loop
750  END REPeat loop
760  RETurn conv$
770 END DEFine CONVERT$
```