Micro­power

Judging by the experience of our local club, it is not pssible to recommend any particular recorder. Some manage quite successfully with cheap, battery only recorders. However, I would suggest that you get as good a one as you can afford, preferably with tone and volume controls and a tape counter. Look also for one that, in addition to a standard DIN socket, has a separate speaker or earphone socket, as I have found that I get the best results by writing to the tape through the DIN socket but reading with TP7 on the Nascom 2 board connected to the external speaker socket. Also, take care to use screened leads to connect the Nascom to the tape recorder, and make sure that the screening is grounded by connecting it to TP8.

Having acquired a decent recorder you will have to find the settings for reading and writing by trial and error. Once you have found the optimum positions, and, if necessary, adjusted VR1 for the correct Baud rate, you should not need to alter them again. If subsequently you find you cannot read your own tapes, you should suspect dirt on the tape heads, a bad connection somewhere, or a poor quality tape. Reading other peoples tapes can be quite a problem; often their (or your!) tapes are misaligned, or the level they record at is wrong for your system. It is not uncommon for two Nascom owners who can both read their own tapes with complete reliability to be unable to load a single block of each others tapes. Of course, each thinks the other’s tape system is to blame.

Well, that’s enough on hardware, so back to Basic.

Getting Basic – Episode 2

Like most Basics, Nascom’s Microsoft can be used in both direct and indirect modes. In indirect mode a line number is first typed, followed by one or more commands. The commands are not carried out as they are entered, but are stored internally to be executed later. The lines of commands are stored in numerical order, and it is normal to use line numbers which increase on steps of 10, so that lines can be inserted later to modify the program. The order in which you enter the lines is unimportant; when you LIST the program you will find that they have been sorted by the BASIC interpreter into numerical order. The ability to insert lines into a program is very important. A first attempt at writing a program always contains logical errors (well, my programs do!), usually called ‘bugs’, and these can be eliminated by inserting and/or deletion of lines, so remember to leaves gaps between your line numbers. Deletion of a line is simple – just type the line number and press enter; erasing the whole line from the screen (e.g., by typing ‘escape’) does not eliminate the line. It is still in the internal store, and when you list the program you will find it has not been removed.

In direct mode a command is typed in without a line number, and it is executed as soon as you press enter. The command is not stored internally, and it is therefore lost after is has been executed. For example, if you type PRINT 10*2 and then press Enter the computer will work out the value of 10 multiplied by 2 (Basic uses the asterisk for the multiplication sign) and print the answer. Many commands, for example LIST and LINES, are used exclusively or mainly in the direct mode, while