Original instructions for the Newsfield magazine sub-editor follow:
This is in FIVE sections: the first part forms an 'editorial', summarising the trends in the market; then comes the main Tech review, covering CP/M and Mallard BASIC - this part can be printed in condensed type if space is short, but please make sure it's not on a dark blue background (e.g. the Xmas special) as readers find that combination hard to read. Then I preview the NEW Plus Three material I'll cover in next month's feature (along with anything else that comes in). Then comes a short feature on a project to get the CPC machines to run Spectrum BASIC - light relief as CP/M works the opposite way - and the usual 'trailer' for next month.

SPRING SURPRISES - TECH TIPS #30 - CRASH JUNE 1988



Spring has been fruitful for the Spectrum market this year, with a flood of new Plus Three utilities, a conversion of ZX BASIC for the Amstrad CPC range, and signs of Amstrad's long-forecast shift into the computer-music market. Simon N Goodwin reports on the changing face of the Spectrum...

PLUS THREE RUSH
Original software for the Spectrum Plus Three is flooding onto the market at last. In the last few days I've received three new serious programs from Tasman Software, a clutch of utilities from ZX Guaranteed, and news of new Plus Three titles from Lerm, BetaSoft and HiSoft.

Most importantly, Locomotive Software have at last put the CP/M Plus operating system on the Spectrum. This move has been predicted since 1982, though it was not technically feasible till the launch of the Plus Three. CP/M doubles the size of the Spectrum's software-base at a stroke, and changes the Plus Three from a specialist games box into a bargain-priced general-purpose computer.

At last it looks as if the Plus Three is here to stay, despite its high price, technical quirks and lack of compatibility with older Spectrums. Software houses are breaking away from the 'toy market' image, taking advantage of the Plus Three's standard ports, and bringing Spectrum users 'serious' applications software.

It's not yet clear how this will affect the main Spectrum market. Machine-specific games will always dominate Spectrum software sales by volume, because - as publishers know well - they are disposable products in an ever-changing fashion market.

The Plus Three is a valuable part of Amstrad's range, but it's a hybrid product: a CPC/Spectrum clone rather than a true Spectrum. At least for the time being, if you only want to use Spectrum-specific hardware and software, you're better off with a Plus Two and a Plus D or Swift Disk - but the Plus Three is gaining a unique character.

It's interesting that Amstrad have put the price of the PCW 8256 range up to around twice that of the Plus Three; they seem to be protecting its status on the borderline between games and serious computing.

There are strong signs that Amstrad have chosen a new direction for their mass-market entertainment products. If you've been paying attention over the last three years you will not be surprised to hear that they're moving into music-making. DIY music is going to be a very, very big hobby, and an extension of home computing as distinct and popular as game-playing or word-processing.

After the Plus 2A - the Plus Three with cassette - it looks as if the Plus Four will have add-on music hardware, probably similar to the RAM Music Machine hardware, designed by ex-Sinclair staff at Flare. No one - even at Amstrad - knows when this will appear as I write, and the first Amstrad home-made music product is not a computer.

The Studio 100 started to get TV advertising in April, when it reached a few high-street shops. It's a four track tape recorder, which lets you build up a stereo recording from up to 10 parts, recorded separately. It also includes a six channel mixer, to combine sounds and effects, four grotty microphones, speakers, uncomfortable headphones, an echo generator and a complete music-centre - including a second tape deck, turntable and a three-band stereo tuner.

There's a ominous 'DATA' connector on the back, and the manual - by Plus Two manual editor Ivor Spital - just hints that it is 'reserved for future Amstrad add-on products' - believe it!

The Studio 100 is a fabulous peripheral for a sampler or SpecDrum, and at 300 it's excellent value. The sound quality is not brilliant, but tolerable, as you'd expect from Amstrad.

At first, the Studio 100 is sure to sell well for other reasons. Staff in my local Currys cynically reckon most punters won't know what it's for, but they'll buy it because it has more knobs and switches than anything else in the shop: 33 knobs, 7 faders, 22 switches, 21 buttons, 17 sockets and a lever!

Once people have got it, they won't be disappointed, as long as they can find time to play with it. We can expect a steady stream of interactive music products from Amstrad in the next few years.




CP/M EMANCIPATION
Despite its success in the specialist games market, the Spectrum has always been a general-purpose computer. Until recently it has been handicapped by an obscure operating system, no standard disks and a limited home TV display resolution. Locomotive Software have addressed all three of these problems, with the launch of CP/M Plus for the Plus Three.

CP/M HISTORY
When computers first appeared they were all totally incompatible, like games machines today. After a while people decided it was a waste to re-write programs for every new machine, so they dug out a program written in 1974 that would control disks and a simple display on ANY computer with an 8080 processor, or it's souped-up successor the Z80. The program was called Control Program/Monitor, or CP/M for short.

CP/M was important because it meant programs could be written once and work on lots of machines without changes. All the machine-specific bits were handled by calling the control program. This was a bit slow and restrictive - it ruled out graphics and sound - but it was worth it, because thousands of CP/M programs were written - programming tools, business software, and text games like adventures. Many programs are available at just the cost of a disk and duplication - a few pounds - from legal 'public domain' software libraries like PD-SIG: 0896 63298.

SPECTRUM CP/M
Spectrum CP/M only runs on the Plus Three. It consists of a single three inch disk, brim full with 346K of files on both sides, and a hefty manual. It loads from the Plus Three 'loader' option in about 10 seconds, plus another 10 while it automatically configures the serial port and an 11K RAM disk (drive C).

Once CP/M is loaded you have about 61K of fast memory free for programs, with no need for 'paging'. Usually on a Plus Three the screen and ROM mean you only have about 40K free in one space, plus a 64K RAM disk. In CP/M up to 15K of otherwise unused memory can work as a fast but small simulated disk - useful when copying small files with only one drive. The rest of the 128K contains the code of CP/M, which runs entirely independently of the Spectrum ROM.

CP/M COMMANDS
Spectrum CP/M Plus has 37 standard commands, but there's no maximum - the package includes facilities to make your own commands, in BASIC, machine-code or by chaining together existing ones. If you type a word CP/M doesn't know, it automatically looks for a file of that name and either executes it, if it's a program, or reads commands from it as if you typed them, if the file contains text. This simple scheme is very powerful.

Plus Three CP/M initially recognises 15 'housekeeping' commands. The simplest is TYPE, which shows a named file on the screen, waiting for a key between pages.

You enter DIR to find the names of disk files. DIR takes about 3.5 seconds to read and display a directory of 27 files - plus an extra eight seconds if you've just changed the disk, and the computer needs to update its record of the disk structure.

DIR (SIZE) uses the separate DIR utility program, and takes nine seconds to load that 15K program, read the same directory, sort it into alphabetical order and display it over 31 lines.

DIR works on Plus Three DOS disks, but TYPE - like most commands - can only decipher the data on CP/M disks. It prints just PLUS3DOS, plaintively, if you ask it to look at a file created by Plus Three BASIC.

SHOW tells you the amount of space in a drive, DATE lets you read and set the date and time, used to mark files. The rather rudimentary Plus Three hardware means that the clock loses time when the disk is accessed. The date reverts to Christmas 1982 whenever you reset the system.

ERASE and RENAME let you remove files from a disk or change their names. SET can protect a file from ERASE. Names can include 'wildcard' characters, as in Plus Three DOS, so you can use one command to process several files with similar names.

DISCKIT copies disks. It takes about two minutes to copy a 173K disk on a single drive computer - a minute to read and write the data, plus another minute for you to swap the disks back and forth eight times.

PIP is the rather clumsy 'Peripheral interchange program'. It lets you copy files back and forth between disks, the screen, serial and parallel ports - but not MIDI, which did not exist when CP/M was designed.

OTHER COMMANDS
There are 10 configuration commands. For example, the PALLETTE command lets you set the foreground and background colours - the default is white on blue.

The other 12 commands are only briefly mentioned in the manual - they are 'advanced programming tools' - well, they were when CP/M was invented, but today they seem a bit crude.

ED is the standard CP/M line editor, and is horrible. Not much better is RPED - a screen-editor for up to 200 lines of text, written by Amstrad in protected BASIC. It's simple to use but very rudimentary, and won't let you copy or move information between lines to the next. RPED is alright if you just want to write a few command-files, but it's not much good for programming.

You get two assemblers, for the 8080 processor rather than the Z80, and can try them out by assembling the well- commented RAM disk source code provided. All the 8080 instructions run on the Z80, but they have different mnemonic names so the source looks pretty odd! To make things even stranger, the program uses Z80 codes which the 8080 couldn't handle, and these are written as 'defined' bytes and words in the program. Even so, it's an interesting example.

KEYBOARD
Like ZX BASIC, CP/M is usually controlled by typing commands at the keyboard. However CP/M lets you change the characters produced by every key, and there's a massive character-set, including foreign accents and loads of weird squiggles.

Some commands use the square and curly brackets, which Amstrad did not mark on the keyboard. Locomotive have positioned these sensibly on unused pairs of symbol-shifted keys. BREAK is the equivalent of CP/Ms 'Escape', and EDIT usefully recalls the last line entered for editing - try doing that in GEM or on an Apple Mac!

EXTEND works as a 'control' key, so - for example Control S and Control Q stop and start scrolling; the TRUE and INVERSE VIDEO keys give the same effect more conveniently.

You can divert input and output to any device with commands. If you've got a printer connected, Extend P is a convenient way to copy all display output to it.

Keys repeat, without over-running, when you hold them down for a while, but there's no key-click, and the cursor disappeared annoyingly when the arrow keys were held to move quickly along the line. Locomotive Software excuse this on the grounds that they try to make the screen display fast, and no-one complained about this bug on earlier Amstrad CP/M machines. They'll try to find a fix, but they don't sound very hopeful.

You can 'type ahead' while commands are running. Sometimes the characters you enter get lost, but usually they appear on the next command-line. The effect depends on what the computer is doing, but it's a useful feature when you get used to its quirks.

The line editor lets you move back and forth through up to 239 characters of command and 'parameters', adding and deleting at will. Unfortunately you can't edit characters unless they're on the same display line as the cursor.

MALLARD BASIC
Mallard BASIC is a 28K code file. It loads from the CP/M command level in about 5.5 seconds, leaving just over 30K for file-buffers, variables and your program.

Mallard BASIC is aimed at serious programmers, and is very like IBM's GW BASIC or Microsoft's MBASIC. You enter program lines of up to 255 characters. The syntax is not checked at once, as it would be in ZX BASIC. If a mistake is found when the line is executed, you are thrown into the line editor.

The BASIC editor works like the CP/M command editor, with extra tricks to move up and down between screen lines, search for a specific character, and delete or overwrite chunks of text. You MUST tell it the width of the screen line with the WIDTH command before it will work in 32 column or 80 column mode, or strange things can happen!

In BASIC the keyboard functions are sadly inconsistent with the CP/M command level - a common problem with early operating systems, where every program has its own conventions. EXTEND A works like EDIT in CP/M, recalling the last line as long as you have not yet started to enter a new command. BREAK is ignored, but EXTEND C will stop your program unless you've protected against it.

Control G is the only way to make a sound, unless you resort to OUT instructions to control the speaker directly. Type Control G in BASIC, to hear a simple 'beep' sound. In CP/M this only makes a sound when you print the character - not when you type it.

Display control is rudimentary, with no graphics commands at all. You have to print control characters to change colours, move the cursor or clear the screen. In ZX BASIC you'd type CLS, but in Locomotive BASIC you must use terminal control codes: PRINT CHR$(27);"H";CHR$(27);"J".

This gibberish means your programs will work on most other CP/M machines, and suits the IBM PC or Amstrad PCW, both of which run Mallard BASIC and use the same control-codes.

Mallard BASIC allows four different data-types: integers, whole numbers between -32768 and 32767, are more concise and slightly faster than other numeric types. They are particularly useful for array subscripts. Maths functions like SIN and LOG use the default 7 digit floating point 'single precision', and real number-crunchers can add, subtract, multiply and divide 16 digit 'double precision' numbers. You pay for the precision in time and memory.

Variable names can be as long as you like, but strings are limited to 255 characters, unlike ZX BASIC. Locomotive BASIC has the big advantage that you don't have to tell the system the maximum length of string array variables.

Like Microsoft and ZX BASIC, but unlike more modern BASICs, Mallard BASIC is not well-suited to structured programming. There's IF..THEN..ELSE, which can be nested but must be one one line, and WHILE..WEND for loops that start with a test.

Unlike Plus Three BASIC, Mallard has proper file-handling and lets you trap errors, mask the bits of integer values, search strings and trace the current line-number. Overall it's much more like Fortran than Pascal, though when it comes to program development it has the edge over both those languages in that it is interpreted, and you can edit and test the code very quickly.

Sadly there's no compiler available. Locomotive say, unconvincingly, that their interpreter is as fast as other people's compilers. Methinks they expect people to use other languages if they need the speed of compiled code.

Three file-handling schemes give you most of the traditional data-processing options, including sophisticated 'ISAM' (Indexed Sequential Access Method) files, usually only found on big multi-user systems.

You can manipulate normal text files, printing lines then reading them back, one by one, in order.

Alternatively you can use 'random access', dividing a preset file space into fixed-sized sections, called 'records'. Later you can tell the system to 'GET' or 'PUT' collections of text and numbers in any section in the file, just by supplying the appropriate record number.

ISAM files come in two parts - one file contains the data, as in a random file, and another file, the 'index', contains labels or 'keys' used to access the data. You no longer need slot numbers, as you can associate any number of keys - strings of up to 31 characters - with any record in the data file. You can use up to eight independent indices with one file. ISAM files can save a lot of work, but it takes a while to get the hang of them and they tend to be wasteful of disk space.

You can't write a shoot-em-up in Mallard BASIC, but it's still a valuable addition to the Spectrum programmer's armoury.

CAN IT BE TRUE?
CP/M is no use unless the implementation is genuinely compatible with the thousands of programs available for the system. Spectrum CP/M has quirks, as you might expect, but it runs most CP/M programs OK.

The disks, at 173K, are small by modern standards, but many CP/M machines had even smaller drives - 88K was not unknown! CP/M software is often sold on 5.25 inch disks, but conversion is not too much of a problem, as lots of firms and interest groups can convert CP/M stuff for CPC and PCW computer users with three inch drives.

Spectrum CP/M seems to work fine with 173K Amstrad disks. Pro Pascal and Pro Fortran, for the PCW 8256, just plugged in and worked, although they were short of space for files on my single drive Plus Three.

Most CP/M systems had two drives. The Plus Three can run a plug-in drive B, but most people won't want to spend that much. Locomotive provide useful two drive emulation on drive A. The system lets you use two disks in one drive, telling you when to swap them.

Beware: this can get very tedious if the program is copying a file, a line at a time, from one disk to another! An optional status line, at the bottom of the screen, says which disk should be in the drive at any time.

Spectrum CP/M can display a maximum of 51 characters per line, or 32 per line with full colour control. Most CP/M packages expect an 80 column display.

To get around this, Locomotive provide a simulated 80 column mode, showing 80 columns in two overlapping 51 column sections. There's a marker on the status line to show which side you're on. Flicking back and forth can follow the cursor, or be manually controlled. Either way it works with most packages, but makes some very hard to use.

Text output is slow: screen updates are about a third the speed of ZX BASIC, in both sizes; scrolling is about 60 per cent of ZX BASIC speed in 51 column mode, but - bizarrely - only 44 per cent of Sinclair's speed when scrolling a 32 column display.

CP/M uses two characters to mark the end of a line. Some printers only expect one, and give double-spaced output when you use them from CP/M. You can cure this by adjusting a switch inside your printer, unless you've got a really cheap and nasty model. You must use the serial or parallel ports - ZX and Alphacom printers won't work at all from CP/M.

DOCUMENTATION
The manual is in three sections. The first 100 A5 pages explain how you use the system - entering and editing commands, performing 'housekeeping' tasks such as copying and editing files and disks, and 'configuration' - customising the system to your favourite key-layout, language or printer.

This part of the manual shows the benefits of CP/M's 14-year life and Locomotive's long experience of the system. It's clearly written, although a long and wordy read for anyone who doesn't like books. It's packed with little comments that show that the authors have actually done what they are writing about.

The next section, 160 pages long, covers Mallard BASIC. It's a tutorial introduction to the language - incomplete but quite a good 'taster'.

The tutorial is no substitute for a a proper reference guide, so the 10 Mallard BASIC Reference Manual is probably a vital purchase if you're serious. It starts with a similar tutorial, followed by an extra 300-odd pages - methinks there's a frustrated blockbuster novelist at Locomotive Software.

The CP/M manual ends with over 100 pages of appendices, covering disk contents, keywords, machine-code system calls, detailed device specifications and error messages. My pre-release copy lacked an index, which Locomotive will add in final version. They recommend that techies buy the Digital Research CP/M Plus Manual, for further information about the programming tools and the design of the system.

VERDICT
At 30 for CP/M Plus, utilities, and Locomotive BASIC, this package is a bargain if you're at all interested in computers for their own sake.

CP/M Plus transforms the Plus Three from an ingenious but aging games machine into an old-fashioned but useful non-specific computer SYSTEM. Like many others, I've found such systems a fascinating kind of general-purpose tool and toy to have around the house. It's fun, but it takes hundreds of hours to learn your way around such a system, and not everyone can be bothered.

Even if you don't want to be a hacker, you can be a 'power user' with CP/M, using whatever parts of it appeal to run a customised computer system for work, business or fun. Suddenly there's more to be read in computer magazines, because you can run all the CP/M packages reviewed in Crash, Amstrad magazines and multi-format titles like Computer Shopper.

PLUS THREE PLETHORA
I've received lots of new and revised Plus Three programs recently, so I'm planning an in-depth survey next month. For the moment, here's a taster.

HiSoft (0525 718181) have new Pascal and C compilers, in two versions. The Plus Three DOS versions support Spectrum colour and sound and cost 35. The CP/M compilers cost 50, but come with a screen editor and let you develop programs for other CP/M machines.

At the same high price they offer CP/M DevPac. That's the assembler they use to write their own programs, and has few of the annoying restrictions I found when I reviewed the Spectrum version in the March issue.

HiSoft also distribute CP/M compilers from other firms. Now you can run Astec standard C, Nevada Fortran and even Cobol on a Spectrum! Astec C is big, costs 80, and includes floating-point maths and a built-in assembler, unlike HiSoft C. The Nevada compilers are aimed at students and cost 40 each.

Tasman Software (0532 438301), authors of the best-selling word-processor Tasword, are taking the Plus Three seriously. They've a new version of Tasword on three inch disk, and TasSpell - a computerised spelling-checker with a 70,000 word English dictionary.

Those two programs run on the Plus Three only, but TasCalc is a new spreadsheet calculating package for any 128K Spectrum; it's the only Sinclair spreadsheet that takes advantage of the extra memory on a Spectrum 128. TasCalc costs 18 on tape, or 20 - like the other Tasman Plus Three titles - on three inch disk.

Lerm Software (091 253 3615) are working on a Plus Three disk management package, and I've just received a bundle of disks from ZX Guaranteed (061 766 5712). These include a rather limited disk doctor, file transfer utilities and simple database programs. Most interesting is '007 Menu', which lets you keep track of up to 2300 files in a 'directory of directories' on one disk.




CPC EMULATION
BetaSoft (021 443 4620) hope to have Plus Three BetaBASIC finished in the next few weeks. They've been waylaid for a while by an experimental project, converting the ZX BASIC language to run on the Amstrad CPC range!

The resultant 9.95 program starts by loading a copy of the Spectrum's 16K ROM from tape. To avoid copyright problems, it's up to you to save the copy from your own Spectrum, by typing:

SAVE "ZX 48K ROM" CODE 0,16384

Betasoft's code can load and save Spectrum-format tape files on the CPC. ZX BASIC programs work fine, although slightly slower than they run on the Spectrum. PEEKs and POKEs are compatible, as are most ROM calls, but few machine-code games will run because IN and OUT cannot find the Spectrum's keyboard and display ports. COPY drives any Epson printer.

There are two display modes. One lets you use four colours anywhere on the screen, with NO attribute clash. The other emulates the Spectrum display; again it only allows four colours, without BRIGHT or FLASH, but this time it simulates the effects of attribute clash, so that even POKEs to the display area work!

The CPC display uses 16K of memory, so it's not as fast as the Spectrum's 6.75K. 16K is taken from the program area on a 64K computer, so you only get about 20K for ZX BASIC, but you get the full 41K Spectrum program area on a CPC 6128.




SUMMER-TECH
In the July issue I plan to survey lots of the Plus Three software previewed in this issue, concentrating on 'new' serious software - the business and programming tools that have been denied to Spectrum owners for the last five years. This will be good reading whether you've already got a Plus Three, are thinking of upgrading, or just want to know what the new machine can do that the old Spectrum could not.

Don't be put off if you're still among the majority with a 48K system. I'll continue to cover the original Spectrum models, and cassette 128s, in this column. Next month I hope to announce some Tech Tape enhancements, and news of Lerm's cheap but powerful Z80 programming tape, set to break the monopoly of HiSoft's DevPac. Don't miss Crash 54!




The above is from the original text, written at the time on a 48K Video Genie computer with half the power of a ZX Spectrum, extracted from a 100K 5.25" floppy disk with a Sinclair SuperBASIC program on my QL which tweaked the non-ASCII characters inserted by Scripsit; Then I read it onto my Amiga 4000/60 from a 3.5" Qdos format transfer floppy, concatenated the 'extent' file (it was a bit too big for one allocation unit on NEWDOS, and my program (MultiDOS_BAS in the Quanta library) creates one file per directory entry as most (up to about 24K) fit that) then I stripped a few more control codes and word-wrapped it with Amiga shell commands, before manually tidying the table (which got a bit messed up in transit) and inserting pound signs that the Genie mapped to hashes. There followed a few minutes of searching and replacing for the HTML conversion in Hisoft Devpac 3, and a run through the W3C Tidy tool to validate it - that's what I call compatibility ;-)

Copyright © 1988-2003 Simon Goodwin, all rights reserved. First published by Newsfield Limited.