The Casio PG 310 was a stratocaster shaped guitar synth. The PG-310 was not just a synth controller but had a built in synthesizer with 64 preset sounds which could be edited on a RA-500 ROM card which fitted into a slot on the PG-310. The PG-310 guitars were manufactured for Casio by Fuji Gen Gakki, who also made the Roland and Ibanez MIDI guitars. The following features and specifications are from the Casio 1987 catalog:

Specifications:

Body: strat shaped alder body
Neck: maple
Fingerboard: rosewood with 22 frets
Pickups: Single coil (PS-581A) X 2, humbucker (PH-641A) X 1
Tremolo: synchronized tremolo unit
Guitar controls: volume, tone and 5 position selector switch.
Preset tone/MIDI controls: Preset tone volume, card key, octave up key, octave down key. chromatic key, program keys (1-8), micro switches (1-10).
MIDI out message: Program change (0-63, 0-126 when using ROM card), basic channel (1-16), mode 3 (poly), mode 4 (poly), velocity and pitch bend.
Electronic tuner: Tuning indicators (sharp or flat), standard pitch (440,441,442,443 Hz)
Inputs/outputs: guitar out, preset tone out, MIDI out, DC 9V
Power: 6 AA batteries or AC adapter. Consumption 2W.
Dimensions: 1000 x 322 x 71 mm
Weight: 3.9 kg
Standard accessories: batteries, guitar cord x 2, tremolo arm, wrench x 2.
Optional accessories: soft case (SC-75G), hard case (HC-51G), RAM card (RA-500), AC adaptor (AD-5).

Features:

Front Key Panel & LED Voice Display
A bright red LED display mounted on the guitar face gives you "at a glance" confirmation of the selected voice number. Built-in program keys give you finger-tip selection of any of the 64 built-in sounds.

Octave Control Keys
Built-in octave control keys let you lower or raise the octave of preset synth sounds. They can also be used to raise or lower the pitch of MIDI sounds when using the PG4310 as a MIDI controller.

Electronic Tuner
A built-in electronic tuner provides accurate tuning readings for individual strings. Just play an open string, indicators located right on the control panel show whether the string is fiat or sharp. And A4 standard-pitch tuning can be set between 440 and 443•Hz. in 1-Hz increments.

Chromatic Function
The PG-310 features a chromatic performance function which allows incredibly realistic emulations of chromatic instruments such as keyboards or vibes. With the chromatic function OFF, the PG-310 responds to bends and slides just like a normal guitar, but switch the it ON and the pitch of preset synth sounds bends up or down chromatically.

RAM and ROM Cards for Unlimited Sound Potential
The PG-310 gives you 64 preset synth sounds—but that‘s just the beginning. Optional ROM cards slide into the slot on the back of the guitar giving you an additional 128 sounds to choose from. Or insert an optional RAM card to utilize original sounds created on Casio's innovative VZ digital synthesizer.

Synchronized Tremolo Unit.
From the slightest singing vibrato to the most outrageous growls and screeches, the PG-310 gives you precision control over string bends thanks to a built-in synchronized tremolo unit.

Multiple Outputs
The PG-310 can be connected directly to an amp for solo performance, or use II as a MIDI master controller by connecting it to other MIDI sound sources or devices. Built-in program keys make it easy to make program changes, so there's no need to be tied down to external MIDI sound sources.