Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

SCI Model 64 Sequencer

Sequential Circuits' MIDI sequencer for the Commodore 64 looks like a bargain at only £185. David Ellis checks out the reality.

Sequential Circuits' Model 64 is one of the first MIDI-compatible sequencers to link directly to a home computer, in this case the popular Commodore 64. David Ellis recently took a sample home for review and here reports his findings, beginning with a hardware rundown.

The Model 64 Sequencer cartridge that the RRP of £185 (or, alternatively, $199) buys you certainly stands out from the crowd, and there's really a mixture of good and bad points in that. The Model 64 is specifically designed for the Commodore 64 micro (hereafter abbreviated to C64) or its all-in-one travelling companion, the SX64. Whereas the C64 costs under £200 in most High Street purveyors of micro fun, the SX64 is much more tastefully packaged, and comes complete with a built-in 5" colour monitor, 5.25" disk drive, and (trendily) detachable keyboard. It'll even sit quite happily on top of a Prophet T8, assuming you can afford one after you've parted with £800 for the computer. The other difference between the two Commodore stablemates concerns the position of the cartridge socket - the way and means of turning the micro into a more or less dedicated games machine, or, in this case, a multitrack, real-time sequencer.

On the plain C64, the cartridge socket is to be found at the rear of the machine. The SX64, on the other hand, puts it on the top, partly protected by some hinged flaps. Now, both of these sites create problems for the Model 64. In the case of the C64, the LEDs on the top of the cartridge tend to be less than conspicuously obvious if a monitor is placed in the position shown in SCI's adverts. In fact, anyone seeking to prove the company's advertised point that the Model 64 Sequencer is designed for use 'with or without a monitor' may have a tough time deciding who's flashing at what (or vice versa). On the other hand, the SX64, sites the cartridge in the firing line for any inadvertent knock to sever its relationship with its host.

Anyhow, design sidetracks apart, the cartridge includes sockets for MIDI in and out, clock in, and a start/stop foot-switch. The aforementioned LEDs (ten in all) give a cunning readout of status (record, playback, and overdub), the nature of the sequencer's current preoccupation (sequence or song), the corresponding number (1-9), and whether or not there's an ongoing interactive situation with a cassette recorder. Finally, there's a series of four DIL switches that allow selection of the number of clock pulses-per-quarter-note from a drum machine.


The major advantage of having software in ROM is that the system's ready to do your bidding practically as soon as you switch on. In fact, if the software that's contained within the 16K ROM in the cartridge had to be loaded up from cassette every time you powered-up, you'd be kept waiting for minutes rather than a second or two. So be grateful for SCI's small mercies.

Everything is menu-driven and generally well protected from user error. The only occasions I managed to crash the system were when attempting to load a sequence without giving it a file name, which necessitated switching-off and starting all over again, or when using the Model 64 with a Roland JX3P, but more on that anon. Unfortunately, that doesn't mean to say that the system performed 100% as you'd expect the rest of the time. In fact, a curious problem surfaced when using the sequencer with just a T8 on its own. As soon as I started to record a sequence, the software immediately switched over to playback, so that you ended up playing along with something like a two-note trill. Hardly a 4064-note sequencer!

On top of that, stopping the playback with the footswitch or by pressing 'Return' left a drone continuing, though this could be stopped by changing the program number on the synth. This drone arises from the fact that the T8 doesn't accept the 'all notes off' protocol that the sequencer sends when playback has finished - a nuisance, but eminently bearable.

A telephone call to SCI's UK representative revealed that he'd always used the sequencer with a Drumtraks rather than with just a keyboard on its own. Taking the 'clock out' signal of the Drumtraks into the 'clock in' of the Model 64 soon revealed that all was much healthier once SCI's other recently-introduced instrument was in charge. True to the copy, all the recorded notes were in their rightful place, complete with effective dynamics from the T8's velocity sensing.

However, something's obviously very amiss if the review sequencer won't operate properly without an external clock input. According to Steve Garth, SCI's service manager in Amsterdam, this is the first time they've heard of this problem, and he assured me that it should function perfectly without a drum machine in tow.

Overdubbing, Editing & Songs

Up to nine sequences can be recorded, but the total event count can't be more than 4064, so that a single 2000-note sequence will obviously leave less room for subsequent sequences. A nice touch is the fact that the monitor updates the display with 'notes remaining' as you're playing, so there's really no excuse for going over the limit unless you are over the limit, if you see what I mean. Anyhow, having put down the first track of a sequence (which is always track 1), the remaining five tracks can be filled up similarly by selecting the Overdub function from the main menu. Note however that all these tracks can be polyphonic.

Even though the software makes provision for selecting Omni, Poly, or Mono mode (by keying 'MO' from the main menu), at present there's no means of assigning particular tracks to specific MIDI channels. So, unless you've got a synth that operates in Mono mode, and therefore feeds incoming channels to specific voices, you're obliged to overdub within the single timbre confines of Omni mode, even if you're using an SCI SixTrak. This will soon change, however...

The Editing function gives you the opportunity to modify the tracks recorded within a sequence. Options include auto-correction (from quarter-notes to triplet 32nds), track erasing, program change erasing, sequence copying/appending, transposition, and playback. In general, the auto correction feature proved invaluable for tidying up sequences or dragging them (by the scruff of the neck) into sync with the Drumtraks. Just occasionally, however, the auto-correction resulted in some untoward (not to mention unwanted) effects in the area of T8 velocity sensing. Sequences that had been recorded and played back with all their dynamics intact had a habit of developing the odd loud hiccup or two after going through the auto-correction system. It sounded to me as if notes on the verge of being auto-corrected out of the sequence were making themselves felt by the addition of auto-corrected velocity bytes, and up to the maximum value of 127 at that! Rather unnerving, to put it mildly...

Finally, there's the Song page which enables sequences to be chained together with or without repetitions and transpositions, simply by keying 'Return' from the main menu and entering a suitable series of numbers. I didn't encounter any real problems here, but I do think SCI would do well to make more use of the display as a 'song' is playing back, ie. having a cursor move from one numbered sequence to another as it's playing back, thereby enabling you to keep track of your whereabouts in the song.


The main problem of ROM-based software is what you do when it comes round to updating the software. The 27128 EPROM is an expensive chip (£25 at the last count), and that makes updating the software by replacement of the ROM an expensive proposition. What SCI have gone for instead is to make provision within the software for update extensions from disk to cassette - forms of data storage which are obviously a lot cheaper than ROMs. Software coming in a month or so's time will add on lots of goodies, including the loading and saving of Drumtraks patterns plus full control of the SixTrak from the Commodore 64. In effect, this will do what the SixTrak does at present in the way of multi-timbral sequencing and stacking, but with all the benefits of the C64's extra memory, processing, and optional disk storage. In addition, there'll be the means of retaining polyphony when the SixTrak is in split mode, plus the flexible assignment of tracks to particular MIDI channels, something that's not possible with the present software.


Given that the sequencer cartridge I was using was purloined from a harrassed SCI executive at Frankfurt who muttered something about it being the only one in Europe, it's hardly surprising that there were a few teething troubles (and no manual!). Being the inquisitive soul I am, I tried connecting the sequencer up to a Roland JX3P to check that Roland and SCI were still seeing eye-to-eye over protocols and the like. The result of this experiment didn't exactly engender confidence, however, because even though the display indicated that notes were being recorded, playback never delivered more than the first note or chord of the sequence. More than that, at one point the screen suddenly indicated 'notes remaining: 7804' and the system promptly crashed.

To be fair, Roland recently spent some time with SCI in Amsterdam, trying out the JX3P and Juno 106 with various SCI products to check that there were no hiatuses. And, by all accounts, everything was pretty much hunky-dory. On that basis, it's somewhat baffling why my JX3P should have a communications blind spot with the SCI sequencer: the one possibility is that my Roland was using Rev 1 software rather than the current Rev 2, a situation that'd certainly confuse the average incoming MIDI stream. So, the moral is plain: check that the software in your JX3P is up-to-date.

How about value for money? Well, given that the Model 64's RRP includes both hardware and software, it really is pretty good. Looking at it another way, some companies are selling MIDI hardware and software for considerably more than £185, and others for considerably less. Viewed against the less immediate competition of the hard-wired MIDI sequencer (the Roland MSQ700, for instance), the Model 64 Sequencer is obviously a cheaper and more intelligent way forward, and, given the promises of the expansion software, it should also be an excellent investment for anyone wanting to get the most out of MIDI at a reasonable cost.

The Model 64 Sequencer carries an RRP of £185 including VAT, and further details can be had from SCI Europe, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

Junk Culture

Next article in this issue

Editing on the Model 64

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


Electronics & Music Maker - Jun 1984

Gear in this article:

Sequencer > Sequential Circuits > Model 64

Gear Tags:

MIDI Sequencer

Review by David Ellis

Previous article in this issue:

> Junk Culture

Next article in this issue:

> Editing on the Model 64

Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for June 2022
Issues donated this month: 0

New issues that have been donated or scanned for us this month.

Funds donated this month: £49.00

All donations and support are gratefully appreciated - thank you.

Magazines Needed - Can You Help?

Do you have any of these magazine issues?

> See all issues we need

If so, and you can donate, lend or scan them to help complete our archive, please get in touch via the Contribute page - thanks!

Please Contribute to mu:zines by supplying magazines, scanning or donating funds. Thanks!

Monetary donations go towards site running costs, and the occasional coffee for me if there's anything left over!

Small Print

Terms of usePrivacy