Conclusions

Using this package is considerably more difficult then using Basic. With a number of fairly minor improvements and with more comprehensive documentation this would become an impressive product.

Source and Price

______, _ _________ ____, Sheffield __ ___. Tel: ____ – ______
Price 35.00 + VAT

MAPP 1-4Z is a 4K floating point arithmetic and functions package for the Z80 processor. It is completely independent of the specific computer or operating system under which it is run. It is also written in position independent code so that it can be moved to and then run in any convenient location in memory.

The package was provided on tape in Nascom 1 format, and the demonstration program provided at the front of MAPP 1-4Z had been written for the T4 monitor, but we read it into a Nascom 2 using NAS-SYS ( and a special hardware interface) without difficulty. The demonstration programs worked at first attempt, and during testing of MAPP 1-4Z, no bugs or faults of any kind were detected. This is high quality software.

MAPP is used by coding an ordinary call to the start of it, which is followed by one or more MAPP instructions. The last of these is EDH which returns control to the ordinary Z80 instruction following. In effect MAPP provides an additional set of instructions for the processor. These instructions treat the Z80 registers in combination providing two 40 bit floating point registers. The effective accuracy is 8 significant digits. While this is better than Basic, it is far short of the conventional “double precision” which has 15 or 16 significant digits. Perhaps a MAPP 2 product could offer this feature.

The real point of MAPP is that you can add its 4K of code to any other program that you develop (normally in assembler), and give yourself good arthimetic capability without the need to write and test your own routines.

It would also be easy to write a demonstration program using MAPP to provide simple calculator capabilities.

MAPP provides:

MAPP also allows for an extended form of call which includes error handling, so that errors in the MAPP instructions can be handled by your program.

The documentation is excellent and is printed and bound. Updates to MAPP are supplied through distribution to registered users by the supplier.

MAPP was written by John Turton of the University of Sussex, and is supplied by:

Enertech Ltd., __, _________ ____, Eastbourne, East Sussex ____ ___.