Consumer-grade home keyboard released in 1985 by Casio. Notable features include cheap synth tones, cheap rhythms, and ultra lo-fi sampling abilities. Below is all kinds of information about this lovely trashy toy that I've grown to love since I received it as a Christmas present as a child.

Fun things to do with your SK-1:
As most people have done as kids, sample your fart, burp, the tv, or noise you want to hear humorously pitched up or down. Hours of fun, and especially good for road trips.

For musicians, especially electronic musicians, its a great way to get lo-fi stuff into your recordings. You won't get any minute-long samples, as the maximum sample length is very short, however it is a great source for percussion and weird effects.

If you sample your fingers flicking the air (make sure its loud enough), the SK-1 will truncate the sample down to just the flick sound. The sample is so short that looping it will produce a woody sounding synth tone that is really pretty nifty.

Circuit Bend it!

Interface:
32 miniature keys
Built-in speaker
Built-in microphone
Audio inputs: 1/4" & 1/8"
Audio output: 1/8"
Power via 5 AA batteries or DC 7.5V

Synthesis:
Sound is produced a number of ways within the SK-1. PCM sampled tones, "harmonic synthesis" tones (a very simple additive synthesizer that is explained below), and sampled tones.

PCM tones:
piano, brass ensemble, trumpet, human voice, synth drums.

Harmonic synthesis tones:
flute, pipe organ, jazz organ

Sampled tones:
input via built-in microphone or audio inputs. 8-bit PCM, 9.38khz, maximum length of 1.4 seconds. Holds 1 sample at a time.

Portamento & vibrato are supported.

There are 13 amplitude envelopes to apply to your sampled sound. Most have names like "damped tone," "organ with attack," or something similarly non-specific. You can get close to echo & reverb, but most will slightly vary aspects of a standard ADSR.

Harmonic synthesis voice:
The last button under "pipe organ" will bring up the harmonic synthesis voice onto the keys. Pushing the "synthesizing" button will switch the SK-1 into harmonic synthesis mode. Your current sound (starts with fundamental) will sustain until the process is complete (synthesizing button is pushed again). You cannot trigger any notes within this mode. Slightly varied sine waves are mapped to 9 keys (16-foot, 8-foot, 5 1/2-foot, 4-foot, 2 2/3-foot, 2-foot, 1 3/5-foot, 1 1/3-foot, 1-foot). Each push of a key within the range will increase the particular sine within the voice. The range of sounds is fairly limited, most ending up sounding like a cheap bell or organ.

Rhythm: 6 drum sounds (bass drum, snare, open hat, closed hat, two toms) used monophonically with tempo control. Fill-in button will insert a fill associated with the current rhythm. Disco (16'), Rock (8'), Pops (5 1/3'), March (4'), Samba (2 2/3'), Bossa Nova (2'), Rhumba (1 3/5'), 4 Beat (1 1/3'), Swing (1'), Slow Rock, Waltz.

Things to know:
The SK-1 has 4 note polyphony.

The memory is volatile, so all sample, sequence, and edited harmonic synth voice data is lost when powered off.

After approximately 7 minutes, the keyboard will shut off automatically.

Accompaniment is available, like most home keyboards, to turn your genius keystrokes into genius keystrokes with terrible matching chords.

Current (as of 10/4/02) used price is $5-50. There are usually a few up on eBay.

Has been used by notable artists such as Fatboy Slim, Beck, Blur, and Portishead.

Modification:
The range of sounds that are possible to produce with the SK-1 is fairly limited, but can be expanded by opening up the case and playing with its pieces. It is a particularly popular keyboard to do this with, as it can be battery-operated and has easily accessible circuits. Popular modifications include a MIDI retrofit and circuit bending.

Related Casio gear:
SK-2
SK-5
SK-8 & SK-8A
SK-10
SK-60
SK-100
SK-200
SK-2100
PT-280
Realistic Concertmate 500
Realistic Concertmate 650
Realistic Concertmate 800

Sources:
Info
http://www.vintagesynth.org/casio/sk1.shtml

Info
http://www.insound.com/zinestand/thumb/feature.cfm?aid=2457

Circuit bending the SK-1
http://www.windworld.com/emi/articles/ghaznw.htm

Info & Manual
http://www.tonymason.com/casio/sk1.cfm

Dr. Joseph Paradiso's SK-1
http://www.synthmuseum.com/casio/cassk101.html

Midi retrofit
http://www.maxmidi.com/diy/sk1/article.html

The SK-1 Manual