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XRI Micon System Controller

MIDI Software for Spectrum Micro

A MIDI interface and sequencer that attempts to do an awful lot on a machine capable of doing comparatively little - the Sinclair Spectrum. Another review by that man Trask.

At last, Sinclair's humble budget home computer gets a MIDI software package that stretches its capabilities to their limits. Minor criticisms aside, it's damn near perfect.

Despite its twin attractions of being both widely used and modestly priced, Sinclair's Spectrum home computer hasn't exactly been a massive hit with the MIDI software writers. But XRI Systems' Micon package, a step- and real-time sequencing affair for the 48K Spectrum that retails at a fairly modest £108, has been flying the Sinclair flag for some while now. It comes complete with a custom-designed MIDI interface, an unexciting-looking black box which connects directly to the Spectrum's user port and has one MIDI In, two MIDI Outs (useful if your synth has no MIDI Thru and you want to include a MIDI drum machine in your setup) and Sync In and Out. Actually, Sync Out isn't used by this particular package, finding use instead (so I'm told) in another XRI product. Both MIDI and non-MIDI drum machines (the latter at 6, 12, 24, 48 or 96 pulses per quarter note) can be used to control either sequencer.

Star attraction of this particular show, with its musical notation score display and extensive editing facilities, is undoubtedly the step-time sequencer, its real-time counterpart enjoying, in truth, the status of bonus feature.


The Micon step-time system allows you to input eight monophonic tracks, each of which may contain up to 2950 events or steps, giving a total capacity somewhere in the region of 24,000 events - these are all dedicated to the single sequence that can be resident in memory at any given time. Each track can be independently assigned to one of the 16 available MIDI channels, too, and that should be adequate for just about anybody's MIDI setup.

Just in case you're wondering, an 'event' is not synonymous with a note in this context. It simply defines the shortest note length to be used on all the tracks, and is selectable from demisemiquaver through to crotchet. Thus, with a quaver-length event selected, you get upwards of 360 4/4 bars per track - a pretty fair number to be going on with, I'd say.

Pitch input is taken from a MIDI keyboard, while duration and gate settings (more on these later) are taken from the Spectrum's QWERTY keyboard. You can enter rests by keying the zero key on the Spectrum once for each event, and you can also select individual tracks for monophonic input, or any number of tracks (up to the full eight) for working in glorious, technicolor polyphony.

Once you've input a pitch from the MIDI keyboard, you enter duration by tapping either the space key or 'q' once for each event duration. Why a choice of two keys for input? Well, the system gives you a choice of two gate settings, ie. the length of time per duration that a note actually sounds. Broadly speaking, this enables you to choose between legato and staccato notes, with the space key selecting the former and 'q' the latter. Each setting can be selected from a wide percentage range, the only restriction being that the 'legato' setting has to be a higher value than the 'staccato' one. Fair enough.

Finally on the features front, velocity information can be accepted from any synth capable of sending it, or it can be input manually from the Spectrum keyboard on a scale of one to eight.

The program's command level is handled on the bottom line of the screen, where lurks the unfortunately 'computerese' prompt: file id buff inp code. However, XRI do a nice line in concise commands - very few of Micon's are more than two characters in length. In fact, moving between Record and Edit modes is so easy that the distinction between the two becomes blurred, itself a reflection of the fact that the editing facilities are so comprehensive that they rapidly become an important part of the compositional process. And a nice feature of the 'bottom-line processing' approach is that the music score remains on screen almost constantly - just one of the features that makes the system easy and fun to use within only minutes of your getting it out of its box.

"Star of the show is undoubtedly the step-time sequencer, with its musical notation score display and extensive editing facilities."

Visual Appeal

One of the step-time sequencer's most appealing features is its music notation display. This takes the form of the standard treble and bass clef pairing, with two bars displayed on the screen at any one time if you select a quaver event duration (I'll leave you to work out what you get with other event settings).

But what I ought to point out straight away is that this system doesn't pretend to be a 'scorewriter' program. The score display is intended simply as a clarification of the music you've entered, a role it fulfils admirably. Featurewise, you're able to scroll backwards and forwards through the entire length of the music you've entered, or position yourself at any bar, the current position being indicated on screen at all times. Any selection of the eight available monophonic tracks can be displayed during Record, Playback or 'non-active' modes, and you can start recording from any bar (providing you first position yourself at that bar), with the display being updated after the input of each note (or chord) and its duration.

Like I say, though, the music display hasn't the thoroughness of a custom-written piece of scorewriting software, because a number of transcription details simply can't be accommodated. Thus, you have to do without such niceties as leger lines, beamed notes, contextual designation of sharp/flat notes, key signatures, rest designations, or upward and downward stemmed notes. And to be fair to XRI, you can't really expect that sort of detail and MIDI processing and a decent amount of note storage from an eight-bit machine like the Spectrum. The designers are also first to admit that realtime scrolling of the score impairs the timing of the music in Playback mode, which is why they've included a facility that lets you turn the scrolling off.

Step Editing

Not surprisingly, the score display also makes step-time editing a lot easier than it otherwise would have been, with the editing commands interacting with the display using the same vertical shaded bar that indicates the current position in the music.

Top line of the display indicates the current command, the current base track together with the number of tracks in use, the number of the current bar, and the tracks currently being played/displayed. And since many of the editing operations are carried out on a single track, it's nice to have the option of being able to focus in on that track, visually as well as aurally.

Gripe time. If you reselect an already recorded portion of a track, it's recorded over automatically without any kind of warning. I can't help feeling some sort of Track Protect function would have been a good idea, but there you go. Some way of recording on any track, rather than the present system of allocating adjacent tracks upwards from a basic track, would also have been handy.

But the system's biggest failing lies in the looping department. You can set a loop point anywhere within the music for playback purposes, but the loop can only return to the start of the piece. This is plainly silly, when a little extra effort could have conjured up a definable start point for the loop (or wrap, as XRI call it) as well.

"A thoughtful inclusion - not so thoughtfully implemented - is the facility to decide precisely what MIDI information you want the system to receive."

Enough of what Micon hasn't got. What do its editing facilities offer? Well, notes and rests can be inserted or deleted from any part, and any single note or rest can be altered by keying 'a' and inputting the new pitch from the MIDI keyboard. Either of the two available gate settings may be assigned to any note individually, as may velocity-sensitivity. Whole bars may be erased in one go, while the 'KILL' facility is as dramatic as its name suggests: it completely erases the entire sequence. Individual tracks may also be transposed up or down in semitones, the only limitation being that the resulting pitches must be within the displayable range (this facility works on a minimum of one bar).

In total, up to 80 patch-change assignments can be distributed across the eight tracks, and once inserted, they can be altered or deleted easily, should you be of fickle disposition. What's more any bar or number of bars can be copied from one place to another, and you can also specify which individual tracks a repeat will operate over. Very useful.

Finally, when you have a piece just the way you want it, the Micon package allows you to save complete step-time sequences or individual tracks to a choice of cassette or Sinclair microdrive. Incidentally, XRI provide keen microdrive users with the means to make a backup copy of the program onto a drive, and to catalogue the contents of a drive from within the program.

MIDI Manipulations

Determined to allow for every eventuality, XRI have made provision for a track-specific MIDI Mode message to be sent during Playback in the step-time system - though make sure you know your MIDI codes (in decimal), as this is how you have to select each message.

On step-time power-up, an Omni/Poly On MIDI message is sent out on Channel 1 - this message is also sent every time you key 'x' followed by . As 'x' is used to exit from Record and Playback modes, it would appear that Mode settings (which also act as All Notes Off commands) are used to ensure that sequences are terminated cleanly. This worked fine with a DX7 and a Casio CZ5000, but keying and 'x' in the Real Time sequencer (to cut short playback of a sequence) caused an Oberheim Matrix 12 to take umbrage, shutting off all its voices and blinking its display windows. No, I can't explain it, either.

As an added operational bonus, you can tailor XRI's program to your own requirements by changing the data governing Mode selection and then saving your own version of the program. This means that if, for instance, you're the proud owner of one of Sequential's multi-timbral wondersynths or a synth with split-keyboard capability and separate MIDI channel assignment (a Jupiter 6, say), you can tailor the Micon system in accordance with your particular MIDI setup. Definitely worthwhile, that.

Real Time

Away from the Micon's showpiece program and on to more mundane fields of play. XRI's real-time sequencer program gives you a one-track polyphonic recorder that allows you to hold a maximum of 10 sequences in memory at any one time; the good news is that memory allocation is dynamically controlled. And as well as the usual note on/off commands, the program can store patch change, pitch-bend and mod wheel information.

"You can tailor XRI's program to your own requirements by changing data and then saving your own version of the program."

The real-time system's menu page presents a far from stunning range of Record, Play, Load Sequence and Save Sequence options, along with a 'Change info' option which enables selection and adjustment of various control options governing sync and timing. The page also displays sequence numbers currently used, together with the amount of buffer space used (expressed as a percentage), with the buffer space figure being updated at the end of each sequence input.

Particularly neat is the way the system lets you derive a metronome pulse from your synth at any pitch within the MIDI range. Not ideal, maybe, but infinitely preferable to the Spectrum's tinny beep. Alternatively, you can choose between either MIDI or non-MIDI sync options. In the case of MIDI sync, Micon controls the MIDI drum machine in Record mode, but can be controlled by the drum machine on playback (beware, you'll have to do a bit of lead-swapping to achieve this).

If you doubt your performing dexterity, you can preset an auto-correction facility to crotchet, crotchet triplet, quaver, quaver triplet, or semiquaver levels, though as none of these is compulsory, mistakes are still a realistic possibility if you want them.

A thoughtful inclusion - not quite so thoughtfully implemented - is the facility to decide precisely what MIDI information you want the program to receive. So if, for instance, you decide you want Micon to recognise MIDI System Exclusive data, it's possible to use a sequence for storing patch dump data, which can be stored on tape and subsequently reloaded into your synth simply by playing the sequence in question. I tried dumping and reloading all the internal voice data of a DX7 and encountered no problems, though you've got to time your button-pushing with some precision to get things the way you want them. One 32-voice dump used up around 15% of sequencer memory, which isn't bad.

However, the implementation hiccup lies in the fact that you have to key in one of three MIDI status byte values (listed in the manual) in response to the system's ignore prompt; the program will then ignore all status bytes with a value higher than this figure. This is something of a programmer's approach to things, caused by over-exposure to (a) the workings of the program and (b) the data manipulated by that program. The poor old musician, meanwhile, has to do without a higher level prompt that could have related to a more generalised understanding of MIDI. Still, that aside, the system gets full marks for clarity and ease of use, so you can't really complain.

What's really inflexible is the way you can only delete the last sequence you recorded. If you're about to embark on your tenth sequence and you want to make some more room in memory by deleting the first, you're going to have a problem or eight.

It would also have been nice to have an Append function along the lines of that introduced by Sequential on their Multi-Trak synth (see review, E&MM May), whereby one or more sequences can be incorporated onto the end of another sequence.


The step-time sequencer is one of the most carefully thought out and easy-to-use systems currently available, no doubt about it. And the fact that XRI have managed to cram it all onto a Spectrum only makes it a more praiseworthy achievement.

Its appeal lies partly in its clear, effective use of graphics and partly in an overall design format that prevents the software from ever imposing itself on the musician using it. The editing facilities are thorough and sensibly implemented, to the extent that even if you've never used a piece of MIDI sequencing software before, you find yourself building up complex pieces very quickly.

In some ways, XRI have accomplished a lot of difficult programming tasks without attending to some of the simpler ones, with the result that the real-time side of the system lacks a number of facilities that would be a piece of cake to incorporate. That's also true of the step-time system (though to a much lesser degree), but then again, the great thing about software is its inherent open-endedness. XRI have already done an admirable job on the Micon, and they deserve every encouragement to continue the good work.

Further Information: XRI Systems, (Contact Details).

Also featuring gear in this article

Micon's No-Con
(ES Apr 85)

Browse category: MIDI Interface > XRI Systems

Featuring related gear

Previous Article in this issue

Microsound Digital Music System

Next article in this issue

The Fairlight Explained

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Jun 1985

Scanned by: Stewart Lawler

Computer Musician

Gear in this article:

MIDI Interface > XRI Systems > Micon

Gear Tags:

Sinclair Spectrum Platform

Review by Simon Trask

Previous article in this issue:

> Microsound Digital Music Sys...

Next article in this issue:

> The Fairlight Explained

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