Integer Pascal:Initial impressions.

From: Datron, _ _________ ____, Sheffield
Cost 35.00 plus VAT

This compiler may well be many microcomputer users introduction to the Pascal programming language.

It comes in a number of versions which are specific to the monitor you use. My copy was designed to run with Nas-Sys 1, and in consequence there may be minor differences in the monitor dependant routines – e.g. the Nas-Sys on screen edit, which is not available under the other monitors.

The program is supplied on a tape, recorded in my case at 300 Baud CUTS, using the Block routines rather than the Tabulate format. It is designed to load at 1000H, and takes some considerable time to load, occupying memory up to approx 3200H. It contains within it a text editor to allow you to build up the program which you wish to compile. This test editor is idiosyncratic (that is, it’s not like any text editors I know), and takes getting used to. It allows a program to be built up, a line displayed, or deleted. It also automatically renumbers the lines of the program when instructed, and has the ability to output a program listing to the VDU or to a printer. It can also save a program on tape, and read it back in. Each line must have a number, but the number does not necessarily put the line in its correct position in the buffer – this is done by a location pointer. Any corrections have to be made by either retyping the line, or by using the Nas Sys on screen edit.

The editor needs each action to be preceeded with a command letter, and the location of the line pointer decides where the line you have just typed/​replaced/​deleted is (or was). The editor works fairly well, but I feel that more work could be done on it, to bring it more towards the way a Basic interpreter builds up a program, which I think would be more familiar to most users.

Having entered the program, the Pascal compiler having been started by the following command :

E1000 Bufferstart Bufferlength

then you can try a compilation. This you do by using the “C” command. When entered on its own with no ancillary parameter, this command causes a trial compilation to take place. As the program compiles, it scrolls up on the screen the lines of the program. Should an error be found, the compilation is aborted, and one of 28 hex values is displayed with an error message. Reference to the manual is necessary to find out what the hex value indicates to be wrong. If the compilation is successful, then you can enter the “C” command again, this time followed by a Hex address, and the Z80 code will be generated there. You can now either leave the compiler, and jump to the code with the monitor E command, or you can use the compiler “G” command to execute the program and return to the compiler when finished.

The compiler occupies Memory 1000H – 3200H, and uses 3200H – 3750H as workspace. Memory outside this can be used for the source buffer, which is defined on entry to the compiler by additional parameters for start and length. If these parameters are omitted on first entry to the compiler, an error message is printed, and you are put back in the monitor.

As can be seen from the above figures, a 32K system would be desirable, particularly if you wish to write a long program in Pascal.