Chris Jenkins assesses whether there'll be a rush to buy Siel's CMK49 designed to control SID.

Over the past few months there's been a flood of musical software and hardware for the Commodore 64, the world's most popular home computer. Considering the large numbers sold, the availability of peripherals and the power of the machine, it's not surprising that it's become the "industry standard" for home computer musicians.

The 64's Sound Interface Device chip (SID) is a powerful three-voice synthesiser in its own right, and so the 64 can in effect function as a musical instrument without the need for any add-ons—if you can program it. Most users, though, prefer to use commercial synthesis and composition packages like Ultisynth or MusiCalc.

However, the 64 doesn't really qualify as a musical instrument because, as with any other home computer, it's impossible to play in real time on the QWERTY keyboard. Several manufacturers have attempted to rectify this problem, notably Autographies with the Microsound 64, LVL with the Echo 1 and Commodore with the clip-on Music Master.

The problem with all these systems is that they aren't open-ended. SIEL now seem to have cracked the problem with the introduction of the CMK 49, which offers MIDI capability as well as control over the SID chip. Costing £125, the CMK is a four-octave full size device which comes complete with software on cassette or disk and with a manual. It's a very smart, slimline unit in grey plastic, looking something like the SIEL line of synthesisers and home keyboards.

Easy action

The key action is very positive, and the unit strongly constructed. From the rear, which is otherwise unencumbered by sockets, comes a sixteen way ribbon cable terminating in a cartridge port connector which plugs into the back of the 64. The connector has a follow-on socket which allows a MIDI interface — specifically the SIEL unit — to be connected, making it possible to play any MIDI equipped synth with the CMK keyboard.

The tape-based software takes several minutes to load the master program and preset sounds. What you end up with is a fairly limited but easy-to-use system for defining sounds on the 64, although it's important to note that's there's no "compositional" element to the software at all — unlike many other packages, the CMK's software doesn't let you store and replay tunes. Presumably this facility will be offered in later software.

The main menu has six options; Edit Play, Polyphonic New Sound, Monophonic New Sound, MIDI Master Keyboard, Disk/Tape Operation, End of Job.

The first, Edit Play, allows you to scroll through the catalogue of preset sounds, some of which are very useable. The SID chip's three voices will never sound like a genuine polysynth, but you can get some pleasant Casio-like chords, and more complex synth noises by switching one or more of the oscillators to act as modulation sources.

Polyphonic sounds like Harpsichord, Piano and Strings are reasonable, but there are some unexpectedly good monophonic sounds such as Harmonica and Musette. In monophonic mode the CMK has high-note priority, so you can achieve good trill effects à la Rick Wakeman.

The special sound effects settings like UFO and Explosion are a little disappointing, and there are only a few of them. Since the 64 can produce some astoundingly complex effects using ring modulation, filtering and sync, it's a pity these weren't exploited more even though they're not strictly musical.

As with most synth presets, you'll probably find that you can create better sounds yourself. This is very straightforward — you can either modify an existing preset or start from scratch, selecting mono or poly mode from the main menu.

Having created and named your sounds you can save them to tape or disk using the SAVE option, and reload any selection again using LOAD. In this way you can build up an unlimited library of sounds.

The edit page comes up when you select any preset, or sound programming mode. The parameters of the SID chip are laid out logically, though not all of them are exploited. The 64's function keys are used to select the control section and the specific parameter to be altered, and the + and - keys alter the parameters or toggle them on and off.

Attack, Decay, Sustain and Release are set from 1 to 15, but this can't be done separately for each of the three voices. Waveshapes (triangle, sawtooth, square and noise) can be selected for each voice. The most powerful aspect of the SID chip is the filter, which has low pass, band pass and high pass modes, cut-off and resonance settings. The CMK software lets you use most of these facilities, but does not let you mix filter modes as do some software packages.

The final options include sync/ring mod/mute facilities which are useful for special effects and modulation.

After setting the sound as desired you hit a function key to switch to keyboard mode, and play away.

The 64's sound abilities aren't demonstrated to their best through the speaker of a TV, so it's wise to use the Audio output DIN socket to wire it into your hi-fi or recording system.

The MIDI master keyboard option, in conjunction with the MIDI interface which costs around £99, allows you to play a MIDI synth or keyboardless expander from the CMK, or to control two MIDI synths with a keyboard split. The keyboard split controls couldn't be easier; just select split mode, define the MIDI assignment channels for the two synths, and press the CMK keys at the point where you wish to initiate the split.

The final option, End Job, resets the computer. It's worth noting that the two automatic demo tunes, excepts from Bach and Beethoven, are pretty weedy and are largely useful only to test if the system is working.

The most striking aspect of the CMK system is that it's designed to be expandable. Future plans include an external voice generator which will supplement the SID chip's voices and act as a processor. There's also the possibility inherent in the system for much more complex MIDI control, sound sampling, keyboard-driven multi-sequencing composition, and so on. The hardware itself is well put together and reasonably priced, although there are reservations about the package as a whole. The manual is adequate but no more, since it goes into no detail at all about the SID chip and makes no suggestions as to how to program different sounds. It could be argued that this can be learned from studying the preset parameters, but copying parrot-fashion isn't the same as learning. Experienced computer owners will have little difficulty understanding what's going on, but new users may be confused by the intricacies of the SID chip.

The major criticism of the package is that the software has no compositional element at all. All the other software packages, and some of the hardware units available, allow the user to define rhythms, sequencers and whole tunes, store and modify them, and perform some degree of "multi-tracking". The only way to do this with the CMK 49 would be by playing by hand onto tape.

In conclusion, the same restrictions apply to the CMK package as apply to all other computer music systems. The hardware is good, but the limitations on the system are imposed by the scope of the software. Fortunately the CMK system is off to a good start, and with the addition of further hardware and software it could become one of the most attractive options for the musical 64 owner.