---
title: "Auto RAMTOP"
id: 76316
type: "computer_media"
slug: "auto-ramtop"
url: "http://localhost/computer_media/auto-ramtop/"
markdown_url: "http://localhost/computer_media/auto-ramtop.md"
published_at: "2026-11-11T08:03:12+00:00"
modified_at: "2026-11-11T08:03:12+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2026/11/auto-ramtop-1.png"
excerpt: "Tell it how many bytes your machine code needs, and this ZX81 program works out the new RAMTOP and can set it for you."
post_tag:
  - name: "Downloadable"
    slug: "downloadable"
    taxonomy: "post_tag"
    url: "http://localhost/tag/downloadable/"
  - name: "TS 1000"
    slug: "ts1000"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts1000/"
  - name: "ZX81"
    slug: "zx81"
    taxonomy: "post_tag"
    url: "http://localhost/tag/zx81/"
model:
  - name: "Sinclair ZX81"
    slug: "zx81"
    taxonomy: "model"
    url: "http://localhost/model/zx81/"
  - name: "Timex/Sinclair 1000"
    slug: "ts-1000"
    taxonomy: "model"
    url: "http://localhost/model/ts-1000/"
indiv:
  - name: "Todd Montague"
    slug: "todd-montague"
    taxonomy: "indiv"
    url: "http://localhost/indiv/todd-montague/"
genre:
  - name: "Utility"
    slug: "utility"
    taxonomy: "genre"
    url: "http://localhost/type/utility/"
media_type: "Program"
programmers:
  - name: "Todd Montague"
    slug: "todd-montague"
    taxonomy: "indiv"
    url: "http://localhost/indiv/todd-montague/"
download_url: "https://archive.org/download/timex-sinclair-software-archive/Auto%20RAMTOP%20%281983%29%28Montague%2C%20Todd%29%28TS1000%29%28US%29%28Program%29.zip"
mediadate: "1983"
images:
  - url: "http://localhost/wp-content/uploads/2026/11/auto-ramtop-1.png"
article_media:
  - id: 19534
    title: "Set RAMTOP Automatically"
    type: "article"
    url: "http://localhost/article/set-ramtop-automatically/"
media_type_tags: "Utility"
license: false
---

# Auto RAMTOP

Reads RAMTOP, asks how many bytes your routine needs, and prints the new RAMTOP in a box with the two numbers to POKE into 16388 and 16389. Answer Y and it POKEs them and does NEW, so the space is protected; N leaves things as they are. Run it before loading or typing your own program.

The article also suggests using it to speed up a program by lowering RAMTOP by the memory the program doesn’t use. SAVE it before you run it, since line 995 wipes it out.

Published in Syntax August 1983 ([Set RAMTOP Automatically](https://timexsinclair.com/article/set-ramtop-automatically/)).

## Source Code

```
   5 SLOW
  10 LET RT=PEEK 16388+256*PEEK 16389
  20 PRINT TAB 10;"RAMTOP=";RT
  30 PRINT
  35 PRINT "HOW MANY BYTES IS YOUR ROUTINE?"
  40 INPUT BYTES
  45 PRINT
  50 PRINT TAB 10;"BYTES LONG=";BYTES
  55 LET NA=RT-BYTES
  60 LET A=NA/256
  63 PRINT
  65 PRINT "MAKE RAMTOP=";NA
  70 LET A$=STR$ A
 100 FOR X=1 TO LEN A$
 110 IF A$(X)="." THEN GOTO 200
 120 NEXT X
 200 LET A$=A$( TO X-1)
 210 LET A=VAL A$
 230 LET RE=NA-256*A
 800 PRINT AT 8,3;"▛▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▜"
 810 PRINT AT 9,3;"▌";AT 9,21;"▐"
 820 PRINT AT 10,3;"▙▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▟"
 830 PRINT AT 9,4;NA;"=";RE;"+256*";A
 840 PRINT
 850 PRINT
 860 PRINT "DO YOU WANT MEMORY SET TO ",NA;"?"
 870 LET Q$=INKEY$
 880 IF Q$="Y" THEN GOTO 950
 890 IF Q$="N" THEN GOTO 999
 900 GOTO 870
 950 PRINT
 960 PRINT TAB 11;"DONE"
 970 PAUSE 80
 980 POKE 16388,RE
 990 POKE 16389,A
 995 NEW
```