Elbug


Acorn Electron

Author: Mike Williams
Publisher: Acorn Computers
Machine: European Machines

 
Published in Elbug #1

Introduction

The Electron is the third microcomputer to be produced by Acorn in almost as many years, and follows the Atom and the enormously successful BBC Micro. Indeed, the Electron is not a completely new machine for it contains many of the features that have made the BBC Micro so popular. In appearance, the Electron is quite new and its smart looks are sure to attract many customers. The price of £199 will also bring the Electron within the pocket of many potential purchasers. So what do Acorn provide for the money?

First of all, it looks as though the supply difficulties encountered by the early BBC users will not be repeated with the Electron. Our review machine was a production model, and this is a good sign, as it suggests that production lines have been gearing up since well before the launch. In other ways too, Acorn has learned from their experiences with the Beeb. The packaging has been well thought through, and the documentation is far better than that received by early Beeb owners.

Electron Pack

Apart from the machine itself, the pack contains a large moulded plug with built-in transformer, a UHF TV lead, an introductory cassette, and two books. One of these is a manual, spiral-bound for easy opening. This is well planned, with a detailed list of contents. A strong minus point is its lack of index, and we would urge Acorn to append an index to the release version of the manual. Apart from this, the manual is excellent. The introductory chapters have clearly been written with great care to introduce the new owner gently to the use of their new Electron. Later chapters provide a comprehensive guide to the BASIC language and to 6502 assembler.

The second book, Start Programming With The Electron by Masoud Yazdani (published by Addison-Wesley) is an admirable introductory text. What is so impressive about it, is that it introduces fully structured programming right from the start. In the first chapter it introduces the PRINT statement alongside PROC and ENDPROC. Procedures are fundamental to strctured BASIC, and it is nice to see them being introduced in this way. Our one serious reservation about this book is again its lack of index in the release version. We have, however, managed to obtain a full index from the author for publication in this first issue of ELBUG, and we understand that this index will be included in future editions of the book.

Machine Hardware

The machine is well constructed, and has a good feel to it. It has a good quality keyboard of 56 keys, though this is rather noisy in operation. The keyboard allows entry of both upper and lower case characters and includes a number of special keys, such as the cursor keys, all of which provides flexibility and convenience. A function key (marked FUNC) allows all the number keys to be defined by the user (see article in this issue of ELBUG on Programmable Function Keys) while the same FUNC key used with other keys on the keyboard allows direct entry of most BASIC keywords. This is a useful facility implemented by the Electron's Operating System.

As far as external considerations go, the Electron is rather limited as it only carries six connections to the outside world. Somewhat unexpectedly, three of the Electron's sockets are for the visual display (UHF, video and RGB). This leaves the power input socket, a cassette socket (with motor control), and an edge connector to be used with external interfaces. There is no provision for the connection of a printer to the basic machine, possibly the most obvious omission, nor is there any provision to connect disc storage units at present. However, it is unlikely that many Electron users will be bothered by this initially.

Acorn has a number of planned add-ons to upgrade the Electron, but these will not be available for several months, though add-ons from other supplies have been announced.

Innards Internally, the Electron's circuitry is well laid out. There are two separate circuit boards, one for power supplies and the main computer board containing the CPU or Central Processing Unit (6502A). This board also contains 32K of user memory together with BASIC in ROM, and the Electron's Operating System in EPROM. Be warned though, as you will lose at least 11.5K of memory for use by the Operating System and for graphics, which can grow to as much as 23.5K in some modes. This can cause prolems for experienced users but is unlikely to trouble the beginner. See Electron Graphics Part 1 for further details.

Principal Features

The version of BASIC used on the Electron is the same BBC BASIC used in the BBC Micro. This provides, on the Electron, seven different display modes giving a choice of 20, 40 or 80 characters per line, high, medium or low resolution graphics, and up to 16 colours. These actually consist of six colours plus black and white, all of which can be steady or flashing colours, to give the total of sixteen. There is also a trade off between the number of colours available at any time and the resolution (the best resolution is 256 points vertucally by 640 points horizontally but only allows two colours). Remember too, that the quality of the image will also depend upon the TV or monitor you use with your Electron.

Overall, the Electron really is capable of very good colour graphics, and these facilities are very easy to use from BASIC. Even the noivce programmer will find it easy to produce interesting and colourful displays. The graphics represent one of the best features of the Electron and so we have included in this issue of ELBUG, the first of a series of articles, telling you how to make the most of your Electron's graphic powers.

A series of commands controls the choice of colour and the drawing of lines and filling of areas. A powerful feature is the ability to define your own graphics characters, which is very useful when writing games programs. There are also two sound channels, controlled by the SOUND and ENVELOPE commands and this is another fascinating feature of the Electron that we shall be talking about in future issues of ELBUG.

BBC BASIC also includes all the usual mathematical and string handling functions plus file processing instructions. One of the most powerful features of BBC BASIC is the provision of structure dprogramming support, particularly in the form of procedures. This encourages the writing of clear, readable programs and greatly assists in program development. The book by Yazdani, included in your Electron pack, is a good introduction to this style of programming.

BBC BASIC also contains a good 6502 Assembler, and machine code routines are readily incorporated into BASIC programs. Your Electron also provides a good screen editor. This is not a full screen editor, as found on some micros, but is is very easy to use indeed. With a program listed on the screen, four cursor control keys are used to move the cursor around the screen, and the COPY key allowed new instructions to be created by copying existing characters from the cursor position. This is a feature which works very well in practice.

Value For Money

Although not immediately apparent to the user, one of the economies that has been made with the Electron is to use an unusual configuration of RAM (Random Access Memory). Because of the way in which this memory is addressed, the Electron's speed of operation varies depending on the amount of memory being used to support graphics. Writing programs for action-packed games will need some careful designing to achieve maximum speed. In future issues, we will be introducing you to techniques for getting the best performance out of your Electron.

The Competition

The Electron's competition will be from machines such as the Spectrum, the Dragon and the Vic-20. Broadly speaking, the Electron compares extremely favourably with these, offering a combination of excellent text and graphics, two-channel sound, and a full typewriter keyboard. It also has one of the best versions of the BASIC language available for a micro and its high compatibility with the very popular BBC Micro will add to its attraction at school and in the home. The promised addons should prove to be a further incentive in favour of this well designed micro.

Mike WilliamsDavid Graham