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Inside & Out

Alesis MMT-8
The Alesis MMT-8
  • Dimensions: 31cm x 25.5cm x 57mm (approx.)
  • Weight: 1.3 kg (approx.)

The top plastic flap on the MMT-8 opens to show an abridged version of the manual. Click here for an HTML version of these Instructions.

MMT-8, Instructions flap open
MMT-8 with Instructions flap open

MMT-8, rear view
Rear view, showing input/output sockets

From left to right, the sockets are:

  • CLICK OUT - 1/4" (6.35mm) mono phone jack.
  • START / STOP - see Manual/Footswitch. The socket is a 1/4" (6.35mm) mono phone jack.
  • TAPE OUT/IN - see Manual/Tape. The socket is a 1/8" (3.5mm) mono phone jack.
  • MIDI THRU/OUT/IN - 5-pin 180 'A' DIN socket.
  • POWER, 9V AC - on later versions (such as the one pictured), the socket is a male 2.5mm barrel. On earlier versions, the socket is a female 3.5mm mini.
followed by the ON/OFF button on the far right.

MMT-8, internal view
Internal view

J9, 10 and 11 (bottom left, middle and right, respectively) connect to the button board (J9 and J11) and display (J10), via ribbon cable.

The processor

The processor (the longest chip on the circuit board, middle right) is an Intel / Signetics 80C31, an 8-bit microcontroller with 128 bytes of onboard RAM, and an operating speed of 11 MHz.

Exact markings on the chip are: SC80C31BCCN40, 2299F02, 9001KE


The ROM chip is to the left of the processor, with a white sticker on it. It is a 32kb (8-bit), UV erasable/programmable ROM (EPROM).

Exact markings on the chip are: MMT-8 V1.10, A8AF (M), ALESIS, @ 7-22-89. Note that the release date for version 1.10 was 7-22-89. More about the differences between ROM versions here.


The two RAM chips are directly to the left of the ROM. Each chip is 256 kilobit (= 32 kilobyte).

Exact markings on the chip: SONY, CXK58257P-12L, JAPAN0129E. CXK refers to SONY, 58257 to the size of the memory, and P-12L to other parameters, such as access time.


The lithium battery (3.6 volts) is the purple cylinder on the bottom left of the circuit board.

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