With a Spectrum powered up and your television set tuned in, try pressing a few keys. You’ll see words and letters appearing on the screen, and maybe some numbers too. However, unless you know how to program the Spectrum, it’s unlikely that the computer will respond by doing anything. But don’t worry — nothing can go wrong with it, no matter which keys you press. • Now press the reset button on the left-hand side of the computer, and you’re ready to set your Spectrum to work. The next four pages will give you some demonstrations on the TV screen of what the Spectrum can do.
Table of Contents
Programming a ZX Spectrum
A Spectrum can do a lot of things. But to make it work, you have to give it a set of instructions called a computer program. Here is a collection of short programs that will put your Spectrum through its paces. All you have to do is key in the program instructions exactly as they appear here. The screen pictures show you what to expect. The panel marked How to alter a program will show you how to experiment with the programs yourself.
How to enter and run a program
Each set of instructions is shown in a list called a listing. You’ll see that the program listings contain several sections each beginning with a number — 10, 20 and so on. Each section is called a line in the program (even if it takes up two lines on the screen), and it contains one or_more instructions for the computer. In each program line, you’ll see whole words or abbreviations containing two or more letters, such as PRINT, LET, RND, PI, PAPER and GOTO. These are called keywords and you cannot key them in letter by letter. Instead, find the key on the keyboard bearing the keyword (PRINT is on the P key, for example), and then follow the instructions in the How to key in panel As you key in a line, it appears at the bottom of the screen. When you get to the end of the program line, press the ENTER key. The line now appears at the top of the screen. Then key in and enter each line in the same way. If you press a wrong key by accident, turn to the panel marked How to correct mistakes on the next page. When you have entered all the lines, press R. The keyword RUN appears. Now press ENTER and your Spectrum will spring into action as it runs the program.
How to use Pre-Written Software
When you enter a program into the Spectrum, you produce a sequence of electronically coded signals as you press the keys. The codes go to the Spectrum’s memory, which stores them so that the computer can use them when the program runs. The codes stay in the memory until you either remove them (by entering NEW or pressing the reset button, for example) or switch off your Spectrum. However, it’s not always necessary to key in a program when you want to use your Spectrum. Instead you can buy ready-to-run software, which contains programs that can be fed into the computer directly and automatically. Using ready-to-run software not only saves you the trouble of keying in a program every time you want to put your Spectrum to work, but it also enables you to have a library of programs ready for use that would take days or even weeks to write yourself. Software manufacturers produce programs of all kinds written by the best programmers, and a wide range is available for the Spectrum. Look at the Sinclair Spectrum Software Catalogue to get an idea of the kind of programs you can enjoy and use. Then whenever you want, you can run a particular program to suit your needs.
How programs are loaded into the Spectrum The code signals on a software tape consist of high and low bleeps recorded at the rate of about 1500 every second. When you play back a software tape in a cassette player, the player produces the sequence of bleeps that make up the program. You just connect the cassette player to your Spectrum, and the codes go directly into the Spectrum’s memory. This is called loading a program. On these two pages, you can see how to connect up your cassette player. Pages 14-15 will then show you how to use it.
What does ‘software’ mean?
Software is the general name given to programs that are fed into computers to make them work. Hardware is the term for the actual machinery – the computers themselves and any other devices involved in computing.
Why is software produced on cassette tapes?
Cassette tapes are easy to use and do not require special equipment. An inexpensive cassette player is all that you need to load this kind of software.
What do taped programs sound like?
Play one on your cassette player without connecting it to the Spectrum. You’ll hear a high-pitched screech. This is caused by the code signals going to the loudspeaker in the player instead of the computer. The signals are sent from the cassette to the Spectrum at such a high speed that it is impossible to distinguish the individual sounds.
Are there any other kinds of software?
Yes. You can get programs on ROM cartridges instead of cassette tapes. The cartridges plug into an interface which fits into the back of your Spectrum. A program on a ROM cartridge loads instantly without any waiting at all.
Software is also available on Microdrive cartridges. These contain programs recorded in magnetic form like a cassette tape. Several programs may be present on a cartridge and, unlike a cassette tape, any program can be loaded within seconds rather than minutes. Microdrive cartridges are used with the Microdrive unit.
Which is the best cassette player?
The Spectrum is happy with an inexpensive portable cassette player, preferably connected to the mains electricity supply rather than driven by batteries. The player should have its own volume control but a tone control is not essential. Special computer cassette players are also available. These are designed to store and load programs more reliably than ordinary machines. A cassette deck that is part of a sound system is unlikely to be easy to connect up. Furthermore, the audio (line) output sockets of cassette decks do not produce a sufficiently strong signal for the Spectrum.
Do taped programs need any special care?
Like any form of magnetic storage, programs on cassette may be disrupted by strong magnetic fields. So don’t store your cassettes near anything that uses a powerful electric current. Software cassettes also need to be kept fairly free of dust.