ZX SPECTRUM Introduction
6. Using the cassette recorder
It is rather tedious having to type programs into the computer each time you want to use it. The ZX Spectrum has the facility for recording programs onto magnetic tapes with a normal domestic cassette recorder. If you have a program in the memory try to save it using the following procedure.
If you can save programs on cassette tape you can load them back again later.
Most cassette recorders will work: as far as the computer is concerned, the cheap portable mono cassette recorders are at least as good as expensive stereo ones and give less trouble as well. You will find a tape counter very useful.
The cassette recorder must have an input socket for use with microphones and an output socket for use with earphones (if there is not one try the external loudspeaker socket). They should ha 3.5 mm jack sockets (i.e. to fit the jack plugs on the leads provided) because other sorts often do not give a signal powerful enough for the computer.
Any cassette tape should work although low nose tapes may be better. Having acquired a suitable cassette recorder connect it to the computer using the leads supplied with the ZX Spectrum: one lead should connect the microphone input socket on the recorder to the socket marked ‘MIC’ on the back of the computer and the other should connect the earphone output socket on the recorder to the ‘EAR' socket. (You cannot harm the ZX Spectrum by connecting the cables incorrectly.
When you are using the SAVE command to store a program onto tape, you must make sure that one of the plugs of the lead connecting the ‘EAR' sockets on the computer and cassette recorder is pulled out - either of them will do. If you forget to do this you will get nothing more than a steady note recorded onto the tape, which is useless. The reason for this is that when the cassette recorder is recording it amplifies the signal coming in on its 'MIC' socket, and puts it out on the 'EAR' socket. If this gets back into the computer it will form a loop, which will oscillate, smoothing the signal you were trying to record.
Type some program into the computer, say the squares program in the previous chapter, and then type:
Squares is just a name that you use to label the program while it is on tape. You are allowed up to ten characters in the name which must consist of just letters and numbers.
The computer will have come up with a message Start tape then press any key. We shall first go through a dry run so that you can see what happens: do not start the cassette recorder, but press a key on the ZX Spectrum and watch the border of the TV screen. You will see patterns of coloured horizontal stripes.
5 seconds of red and pale blue stripes, about 1 cm wide and moving slowly upwards.
A very short burst of blue and yellow stripes.
1 second with everything as normal.
2 seconds of the red and pale blue pattern again,
about 1 second of the blue and yellow pattern again.
Try It again until you can recognise all these. The information is saved away in two blocks and both blocks have a lead-in corresponding to the red and pale blue pattern, and the information itself corresponding to the blue and yellow pattern. The first block is a preliminary one containing the name and various other bits of information about the program, and the second is the program itself together with any variables present. The white section between them is just a gap.
Now let's actually capture that signal on cassette tape.1 Position the tape in a part either that is blank or that you are prepared to overwrite.
SAVE "squares" (and ENTER)
3. Start the cassette recorder recording.
4. Press any key on the ZX Spectrum.
5. Watch the television as before. When the computer has finished (with the report 0 OK) stop the cassette recorder.
To make sure that this has worked, you can check the signal on the tape against the program in the computer using the VERIFY command.
1. Turn the volume control on the cassette recorder to approximately halt way and reconnect the 'EAR' lead
2. Rewind the cassette to somewhere before where you started to record previously
(VERIFY is extended mode, then shifted R).
4. Start the cassette recorder playing.
The television border will alternate between red and pale blue until the tape reaches the recording you made; then you will see the same pattern as you did when you saved the program. In the one second gap in the middle, Program Squares will be written on the screen - when the computer is searching for something on tape it prints up the name of everything it comes across. If you see all this pattern and then the computer stops with report 0 OK your program is safely recorded on tape and you can skip the next few paragraphs. Otherwise, something has gone wrong. Go through these questions to find out what.
Making sure your program is saved
Has the name come up?
It not then either the program was not saved properly in the first place or it was, but was not read back properly. You need to find out which. To see if it was saved properly, rewind the tape to just before where you started recording, and play it back through the tape recorder's own loudspeaker (you will probably have to unplug the lead from the earphone socket on the tape recorder). The red and pale blue lead-in gives a very clear, steady high pitched note, and the blue and yellow information part gives a much less pleasant sound, like a morse code message in a hurricane. Both of these are quite loud -at full volume they can easily drown conversation.
If you do not hear these noises then the program probably did not get saved. Check that the right leads are plugged in the right sockets. Make sure that the 'MIC' sockets are connected, and that the 'EAR' sockets are not. It happens with some tape recorders that the jack plug does not make contact if it is pushed right in. Try pulling it out about a tenth of an inch - you can sometimes feel it settling down into a more natural position. Also check that you were not trying to record on the plastic leader at the beginning of the cassette. When you have checked these, try saving again.
If you can hear these sounds as described then SAVE was probably all right and your problem is with reading back.
Check the leads again, and also check the volume level. If it is too quiet the computer will not hear the signal properly, and you will not see the right patterns on the screen; if it is too loud the signal will get distorted - you may be able to hear it coming through the computer's own loudspeaker. There is a wide range of acceptable values in between, but you could try experimenting.
The next case is when the computer finds the program and writes its name up but still goes wrong. Some possibilities are:
You mistyped the name, either in SAVE (when the computer will write the mistyped name on the screen) or VERIFY: the computer will ignore the program and carry on flashing red and pale blue as it goes.
There is a genuine mistake on the tape: the computer will come back with R Tape loading error which means in this case that it failed to verify the program. Save it again.
It is just possible that the volume setting on the tape recorder is not quite right; but it cannot be far wrong because the computer managed to read the first block.
Now let us suppose that you have saved the program and successfully verified it. Loading it back is just like verifying it except that you type
LOAD is on the J key Since it verified properly, you should have no problem loading.
LOAD deletes the old program (and variables) in the computer before loading in the new one from tape.
Once a program has been loaded, the command RUN will run it.
It is possible to buy pre-recorded programs on cassette They must be specially written for the ZX Spectrum: different types of computer have different ways of recording programs, so they cannot use each other’s tapes.
If your tape has more than one program recorded on the same side! then each will have a name. You can choose which program to load in the LOAD command: for instance, if the one you want is called 'helicopter' you could type
(LOAD "" means LOAD the first program you come across which can be very useful if you cannot remember the name of your program.)