Sinclair ZX Spectrum +3
128K Integrated Home Computer/Disk System

Following on from the outstanding success of the established ZX range of computers: the original Spectrum, the Spectrum +, the Spectrum 128 and the new generation Spectrum +2, we now proudly present the ZX Spectrum +3, a machine that combines the very best features of the previous Sinclair models with the added convenience of a fast access floppy disk drive.

The whole is a truly complete computer/disk system which allies established Sinclair technology with AMSTRAD's expertise in integration and engineering reliability and flair for producing a 'no nonsense' all-in-one package.

Software compatibility

The +3 may be used with software written for the earlier models in the ZX Spectrum range. This means that a vast quantity of software of software already exists for the +3. There are literally thousands of titles available covering every conceivable application: games utilities, music, scientific, educational and many many more.


The +3 uses a computer language called BASIC (Beginners' All-purpose Symbolic Instruction Code). BASIC is by far the commonest language for home computers, and +3 BASIC has been designed to be particularly easy to learn and use.

How to read this book

In order to get the best out of your +3, it is vital that you read all the relevant information provided in this manual. If you skip various sections, it is likely that you will come to a grinding halt later on!

Therefore, you should adopt the following reading programme...

Chapter 1 - This chapter shows you how to connect up your +3 system. Note especially the safety warnings regarding the wiring-up of the mains plug.

Chapter 2 - This chapter describes the switching on of the +3 and shows you how to tune in your TV to display the computer's signal. You are then shown how to select an option from the 'opening menu' - and if you don't know how to do that, you'll not be able to use the +3 at all! If, however, you do know how to tune-in your TV and select menu options (perhaps by having previously used a Spectrum 128 or a +2), then you may skip this chapter.

Chapter 3 - This chapter shows you how to load commercially available disk software. If you never intend to use such software, then you may skip this chapter.

Chapter 4 - This chapter shows you how to load commercially available pre-recorded tape software. If you never intend to use such software, then you may skip this chapter.

Chapter 5 - This chapter covers the use of the +3's built-in disk drive (known as drive A:). You may skip this chapter only if you never intend to use the disk drive during BASIC programming (perhaps having purchased the +3 solely to load and run commercially available software (e.g. games)). Note that if you have connected an additional disk drive (B:) to the +3, then throughout the manual you should take any general references to 'the disk drive' as meaning both drives (A: and B:).

Chapter 6 - This chapter introduces you to +3 BASIC. It particular, it describes the editor and certain aspects of BASIC programming that differ from those of other computers. Therefore, even if you are an experienced BASIC programmer on another computer, you should still read chapter 6. Note that you'll require a blank CF-2 floppy disk as you work through this chapter. If, however, you never intend to program in BASIC and have purchased the +3 solely to load and run commercially available software (e.g. games), then you may skip this chapter.

Chapter 7 - This is the one chapter that you may freely skip. It describes the 48 BASIC mode (in which the +3 operates exactly like the 'old-style' Spectrum - even in the editing and programming aspects). This mode is not recommended as anything other than a history lesson for the curious, or for loading old (Spectrum 48 only) tape software. You should certainly not use this mode for BASIC programming; indeed you cannot access many of the advanced features of the +3 (including disk drive, extra memory, RS232/MIDI/AUX interfaces or RAMdisk) from 48 BASIC. Notwithstanding the above, we have provided the relevant information in this chapter for your reference.

Chapter 8 - This chapter forms the very heart of the manual. It is a complete guide to BASIC programming on the +3. If you have programmed in BASIC before, then you may wish to use this chapter merely as a reference guide, searching the main index to find the information you need from one of the subsections. If, on the other hand, you are new to BASIC, you may wish to work through the chapter, one subsection at a time, developing your programming skills as you go. Once you are able to type in and run a program, and have grasped a few of the fundamentals of BASIC, then you may feel confident about skipping ahead to later subsections. If, however, you never intend to program in BASIC and have purchased the +3 solely to load and run commercially available software (e.g. games), then you may skip this chapter.

Chapter 9 - This chapter shows you how to use the +3 as a calculator only. You may skip this chapter if you wish.

Chapter 10 - This chapter illustrates how add-ons (peripherals) are connected to the +3. Peripherals include such devices as a cassette unit, a printer, an additional disk drive, a joystick, etc. So if you're thinking of linking up any device at all to the +3, check this chapter to make sure that you've got the right connections. If, on the other hand, you intend to use just the standard +3 set up (i.e. computer and TV only), then you may skip this chapter.

(c) Copyright 1987 - AMSTRAD Plc.

Neither the whole nor any part of the information contained herein, nor the product described in this manual, may be adapted or reproduced in any material form except with the prior written approval of AMSTRAD Plc. ('AMSTRAD')

The product described in this manual, and products for use with it are subject to continuous development and improvement. All information of a technical nature and particulars of the product and its use (including the information and particulars in this manual) are given by AMSTRAD in good faith.

All maintenance and service on the product must be carried out by Sinclair authorised dealers. AMSTRAD cannot accept any liability whatsoever for any loss or damage caused by service or maintenance by unauthorised personnel. This guide is intended only to assist the reader in the use of the product, and therefore, AMSTRAD shall not be liable for any loss or damage whatsoever arising from the use of any information or particulars in, or any error or omission in, this guide or any incorrect use of the product.

We ask that all users take care to submit their user registration/guarantee cards.

All correspondence relating to the product or to this manual should be addressed to:

Sinclair Computers Division
Brentwood House
169 Kings Road
Essex CM14 4EF

First Published 1987

Extracts from the book 'ZX Spectrum BASIC programming' written by Steven Vickers and Robin Bradbeer

Published by AMSTRAD

+3DOS written by Locomotive Software Ltd.

CP/M is the trademark of Digital Research Ltd.
Acknowledgements to Centronics and Epson Corps.

The following are registered trademarks of AMSTRAD Plc.:
Sinclair ZX Spectrum, +2, +3, +3DOS
AMSTRAD, AMSDOS, PCW8256, PCW8512, CPC464, CPC664, CPC6128
DMP2000, DMP3000, DMP3160, DMP4000, FD-1
AMSOFT, CF-2, PL-1, DL-2

Unauthorised use of the above trademarks, or of the word AMSTRAD, is strictly forbidden.


You must read this...

(Don't worry if you are a little baffled by some of the technical jargon in this section, the importance of these warnings will becomes clearer as you work through this manual.)

  1. Always connect the mains lead of the power supply unit (PSU) to a 3-pin plug following the instructions given in chapter 1.
  2. Do not attempt to connect the PSU to any mains supply other than 220-240V AC 50Hz.
  3. After you have finished using the +3, always disconnect the PSU from the mains supply socket.
  4. There are no user serviceable parts inside the equipment - DO NOT ATTEMPT TO GAIN ACCESS INSIDE THE PSU - THERE ARE HIGH VOLTAGES INSIDE. Refer all servicing to qualified service personnel.
  5. Do not block or cover the ventilation slots in the equipment.
  6. Do not use or store the equipment in excessively hot, cold, damp, or dusty areas.
  7. Never plug in (or unplug) any device from any of the rear sockets while the +3 is switched on - doing so will probably damage both the +3 and the device.
  8. Never switch the +3 on or off while a disk is inserted in the disk drive. Doing so may corrupt your disk, losing valuable programs or data.
  9. After you have switched off your TV (or VDU monitor), do not immediately disconnect the +3 - wait a few seconds or so.
  10. Do not switch off the +3 (or switch on or off any peripheral device connected to the +3) while there is a program or data in the memory that you wish to keep - doing so may make the +3 'crash', losing the program or data.
  11. Always keep the disk drive and disks away from magnetic fields. For maximum data reliability, do not position the disk drive close to your TV or monitor, or close to any source of electrical interference.
  12. If you have connected an additional disk drive to the +3, keep the ribbon cable (to the additional drive) away from mains leads.
  13. Whenever possible, make back-up (duplicate) copies of disks which contain valuable programs. Otherwise, should you accidentally lose or corrupt the disk, replacing may prove very expensive.
  14. Never touch the floppy disk surface itself inside its protective casing.
  15. Do not eject a disk while it is being read from or written to.
  16. Always remember that formatting a disk will erase its previous contents.
[Chapter 1 - Unpacking, Fitting a mains plug, Setting up.]