Alesis MMT-8 User Manual

ALESIS

MMT-8 (MT)

Service Manual

P/N: 8-31-0018-A

The information in this document contains privileged and confidential information.
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you are not authorized, please contact Alesis and destroy all copies of this
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THIS DOCUMENT CONTAINS SENSITIVE

PROPRIETARY INFORMATION.

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COPIES OF THIS DOCUMENT

ATTENTION!

WITH ALESIS, LLC.

DO NOT MAKE ILLEGAL

Confidential Alesis Service Manual 8-31-0018-A

Preface

This document is intended to assist the service technician in the operation,
maintenance and repair of the Alesis device. Together with the User Reference
Manual, this document provides a complete description of the functionality and
serviceability of the Device. Any comments or suggestions you may have
pertaining to the document are welcome and encouraged.

READ THIS!

In addition to any purchase price that Alesis may charge as consideration for Alesis selling or
otherwise transferring this service manual (“Manual”) to you, if you are not a service and repair
facility (“Service Center”) authorized by Alesis in writing to be an authorized Service Center,
Alesis sells or transfers the Manual to you on the following terms and conditions:

Only Service Centers authorized by Alesis in writing are authorized to perform service and repairs
covered by an Alesis warranty (if any), and transfer of the Manual to you does not authorize you
to be an authorized Service Center. Therefore, if you perform, or if the Manual is used to

perform, any service or repairs on any Alesis product or part thereof, any and all
warranties of Alesis as to that product and any service contract with Alesis for that
product shall be voided and shall no longer apply for such product, even if your services
or repairs were done in accordance with the Manual.

All service or repairs done by you or with reference to the Manual shall be solely your
responsibility, and Alesis shall have no liability for any such repairs or service work. All such

service or repairs are performed at the sole risk of the person performing the service or
repairs. You agree that all such work will be performed in a competent, professional and safe

manner at all times and to indemnify and fully hold Alesis and its successors and assigns
harmless in the event of any failure to so perform.

Your purchase of the Manual shall be for your own ultimate use and shall not be for purposes of
resale or other transfer.

As the owner of the copyright to the Manual, Alesis does not give you the right to copy the
Manual, and you agree not to copy the Manual without the written authorization of Alesis. Alesis
has no obligation to provide to you any correction of, or supplement to, the Manual, or any new or
superseding version thereof.

Alesis shall have the right to refuse to sell or otherwise transfer repair parts or materials to you in
its sole discretion. You shall not use, sell or otherwise transfer spare or replacement parts
supplied by Alesis to you (i) to repair or be used in products manufactured for or by third parties
or (ii) to any third parties for any purpose.

You shall not make any warranties or guarantees with respect to the products of Alesis or the use
thereof on behalf of Alesis or in your own name.

The foregoing describes the entire understanding related to sale or transfer of the Manual to you,
and no other terms shall apply unless in a writing signed by an authorized representative of
Alesis.

All Trademarks are property of their respective companies.

Confidential Alesis Service Manual 8-31-0018-A

Warnings

TO REDUCE THE RISK OF ELECTRIC SHOCK OR FIRE, DO NOT EXPOSE
THIS PRODUCT TO WATER OR MOISTURE.

The arrowhead symbol on a lightning flash inside a triangle is
intended to alert the user to the presence of un-insulated
"dangerous voltage" within the enclosed product which may be of
sufficient magnitude to constitute a risk of electric shock to persons.

The exclamation point inside a triangle is intended to alert the user
to the presence of important operating, maintenance and servicing
instructions in the literature which accompanies the product.

REPAIR BY ANY PERSON OR ENTITY OTHER THAN AN AUTHORIZED
ALESIS SERVICE CENTER WILL VOID THE ALESIS WARRANTY.

PROVISION OF THIS MANUAL DOES NOT AUTHORIZE THE RECIPIENT TO
COMPETE WITH ANY ALESIS DISTRIBUTOR OR AUTHORIZED REPAIR
SERVICE CENTER IN THE PROVISION OF REPAIR SERVICES OR TO BE
OR MAKE REPAIRS AS AN AUTHORIZED SERVICE CENTER.

ALL REPAIRS DONE BY ANY ENTITY OTHER THAN AN AUTHORIZED
ALESIS SERVICE CENTER SHALL BE SOLELY THE RESPONSIBILITY OF
THAT ENTITY, AND ALESIS SHALL HAVE NO LIABILITY TO THAT ENTITY
OR TO ANY OTHER PARTY FOR ANY REPAIRS BY THAT ENTITY.

Regarding the Power Supply Fuse

CAUTION: The product under service may employ the use of a
replaceable fuse. Danger of fire or electrocution if fuse is
incorrectly replaced. Replace with only the same type or
equivalent type recommended by the equipment manufacturer.

Regarding the Internal Battery

CAUTION: The product under service may employ the use of a
internal battery. Danger of explosion if battery is incorrectly
replaced. Replace only with the same or equivalent type
recommended by the manufacturer. Dispose of used batteries
according to the manufacturer's instruction.

Confidential Alesis Service Manual 8-31-0018-A

Safety Instructions

Carefully read the applicable items of the operating instructions and these safety
suggestions before using this product. Use extra care to follow the warnings
written on the product itself and in the operating instructions. Keep the operating
instructions and safety suggestions for reference in the future.

1. Power Source. The product should only be connected to a power supply which is described
either in the operating instructions or in markings on the product.

2. Power Cord Protection
step on the cords and such that nothing will be placed on or against them.

3. Periods of Non-use
AC power supply cord should be unplugged from the AC outlet.

4. Foreign Objects and Liquids
openings of the product.

5. Water or Moisture

6. Heat

7. Ventilation

8. Mounting

9. Cleaning

10. Service

11. Damage to the Product

. Do not place the product near heat sources such as stoves, heat registers, radiators or

other heat producing equipment.

. When installing the product, make sure that the product has adequate
ventilation. Improperly ventilating the product may cause overheating, which may damage the
product.

. The product should only be used with a rack which the manufacturer
recommends. The combination of the product and rack should be moved carefully. Quick
movements, excessive force or uneven surfaces may overturn the combination which may
damage the product and rack combination.

. The product should only be cleaned as the manufacturer recommends.

. The user should only attempt the limited service or upkeep specifically described in
the operating instructions for the user. For any other service required, the product should be
taken to an authorized service center as described in the operating instructions.

situations including without limitation when:
a. Liquid has spilled or objects have fallen into the product,
b. The product is exposed to water or excessive moisture,
c. The AC power supply plug or cord is damaged,
d. The product shows an inappropriate change in performance or does not operate

normally, or

e. The enclosure of the product has been damaged.

. AC power supply cords should be placed such that no one is likely to

. If the product is not used for any significant period of time, the product's

. Take care not to allow liquids to spill or objects to fall into any

. The product should not be used near any water or in moisture.

. Qualified service personnel should service the unit in certain

Confidential Alesis Service Manual 8-31-0018-A

General Troubleshooting

While this manual assumes that the reader has a fundamental understanding of electronics and basic
troubleshooting techniques, a review of some of the techniques used by our staff may help.

1. Visual Inspection - A short visual inspection of the unit under test will often yield results without the need
of complex signal analysis (burnt, or loose components are a dead giveaway).

2. Self Test - Alesis products that utilize microprocessor control contain built in test software which
exercises many of the units' primary circuit functions. Self test should always be done following any
repair to ensure basic functionality.

3. Environmental Testing - Applying heat and cold (heat gun/freeze spray) will often reveal thermally
intermittent components (Clock crystals, I.C.s, and capacitors are particularly prone to this type of
failure).

4. Burn in Testing - Leaving a unit running overnight often reveals intermittent failures such as capacitors
that begin to leak excess current after a significant amount of time.

5. Cable Checks - Wiggling cables can reveal intermittent failures such as loose cables or poorly soldered
headers. Remember to check power supply cables as well.

6. Flexing the PC Board - Poor solder joints and broken traces can often be found by pressing the PC Board
in various places.

7. Tapping Componants - Somtimes tapping on a component (particularly crystals) will cause it to fail.

8. Power Down/up - Turning the unit off and back on rapidly several times may reveal odd reset and/or
power supply failures.

9. Reset Threshold - A Variac (variable transformer) can be used to check reset threshold levels. This can be
particularly useful in helping customers with low line problems.

10. Compressors - Using a compressor/limiter is often helpful when attempting to solve low level noise
problems, as well as assisting with DAC adjustments.

11. Sweep Tests - Sweep generators are very useful in checking the frequency response envelopes of anti­aliasing filters.

12. Piggybacking - Piggybacking I.C.s is particularly useful when troubleshooting large sections of logic.
This is especially true when working with older units.

Alesis MMT-8 Service Manual 1.00 v

TABLE OF CONTENTS

PREFACE .........................................................................................................ii

READ THIS!......................................................................................................ii

WARNINGS.......................................................................................................iii

SAFETY SUGGESTIONS..................................................................................iv

General Troubleshooting...................................................................................v

1.00 General Description...................................................................................1

2.00 Power Supply ............................................................................................1

2.10 Battery Backup................................................................................1

3.00 The 8031 Micro Controller.........................................................................1

3.10 Reset ..............................................................................................1

3.20 Memory Mapped I/O.......................................................................2

4.00 Tape I/O.....................................................................................................2

5.00 MIDI I/O.....................................................................................................3

6.00 Keypad Decoding ......................................................................................3

7.00 Metronome Output.....................................................................................4

8.00 Updates and Corrections...........................................................................4

9.00 Troubleshooting.........................................................................................4

10.00 Software History......................................................................................5

11.00 MIDI Implementation ...............................................................................8

12.00 Service Parts List.....................................................................................14

13.00 Service Manual History............................................................................16

INDEX ...............................................................................................................17

Alesis MMT-8 Service Manual 1.00 vi

1.00 General Description

The MMT-8 MultiTrack Recorders power lies mainly in the sophistication of it's software. The
most powerful troubleshooting tools available to the technician are the a good working knowledge of
the MMT-8's operation and the software history in section X.X. Most problems with the MMT-8 arise
from either user error, or older software. The hardware is very simple and should normally prove to
be problem to troubleshoot. Please note here that there are sveral revisions of main PCB and 2
revisions of keypad boards. While latest versions of the main PC Board include most of the
hardware updates, older board revisions will require some additions to bring them up to the current
factory specifications. These updates are discussed fully in section X.XX.

2.00 Power Supply

2.10 Battery Backup

Battery backup is actually more complicated than it might first appear, as it depends on a
good system reset (see section X.X for details) in order to function properly. The actual backup
circuit consists of a battery (3V - 3.6V Lithium), a 10K resistor (R76) for checking standby current
(see below), a "steering" diode (D5), a filter capacitor (C13), and a transistor/resistor/diode
combination (Q11, R79, D6) that acts as a steering diode. This combination may be missing on
older board revisions, and must be installed (see section X.X) to prevent data corruption due to a
significant difference between Vcc, and the amplitude of the data buss.
SRAM standby current should always be checked. While the unit is off, check the voltage
across R76. If the voltage is higher than 80mV (specification, although a 1 to 20mV range is more
normal) then a problem exists. Usually it indicates a bad (or simply wrong) SRAM, or a short,
somewhere along the MEM PWR line. Note, that for a short time, Sony 58256-PM (high power)
SRAMs were being installed at the factory, causing batteries to drain in about 1 year. They should
be replaced with low power versions (58256-LP) when found, in order to eliminate excess battery
drain. We are currently using Hitachi 62256ALPs as replacements.

CAUTION:Danger of explosion if battery is incorrectly replaced. Replace only with the same type or

equivalent type recommended by the equipment manufacturer.

Battery Manufacturer: Tadiran

Type: TL-5101

Rating 3.6V

3.00 The 8031 Micro Controller

The 8031 MPU is the heart of the MMT-8's cont rol section. It handles everything from keypad
input and MIDI I/O, to sequencing. Note that the 8031 data buss serves a dual purpose. This buss
multiplexes between low order addresses (1st 8 bits), and data. Latch U11 is used to hold the low
order address half, during 8031 read and write cycles. The EPROM (U12) is used to hold 8031
program information. The SRAMs (U9, U10) hold system variables, as well as user sequence data.
Z1 provides the 12MHz 8031 clock. MIDI I/O is handled through the 8031's built in RXD (Read
Serial Data), and TXD (Transmit Serial Data) ports. Tape I/O is handled through the built in 8031 I/O
ports. LCD output is handled through memory mapped I/O (see section X.X). Keypad decoding
uses both forms of I/O (see section X.X).

3.10 Reset

The 8031 reset circuit is perhaps the single most important circuit in the MMT-8. When this
circuit is functioning incorrectly, problems ranging from loss of battery backup, to a complete lock-up
of the machine, can occur. A thorough knowledge of the operation of this circuit will greatly facilitate
troubleshooting this unit.

Alesis MMT-8 Service Manual 1.00 1

This circuit uses the differential between raw +10V, and regulated +5V, to generate the
required signals for system RESET. This is necessary due to fact that the system MUST be in a
reset state while powering down, otherwise, random noise on the 8031 data, and address, busses
could corrupt SRAM data, and destroy any hope that the battery backup will work. R11, R12, and
the 5.1V zener diode (D1), work together as a voltage divider to the base of Q1, and is designed so
that transistor Q1 will turn on when the raw +10V supply is roughly 7V. This is to ensure that
RESET does not occur until after the +5V regulator is fully functioning (i.e. +5V rail is solid). If
RESET occurs too early, noise on the +5V rail can cause data corruption. Before the Q1 turn on
threshold, Q2 remains turned on (the base of the transistor being pulled up by R13). This in turn
holds the voltage across C8 at .3 volts. This is below the threshold (set by R17 and R18) necessary
to turn on the comparator U14A, leaving the reset line high (pulled up by R14). Once the raw supply
has reached a sufficient level to turn on Q1 (roughly 7V), Q1 will pull the base of Q2 low, turning it
off. This allows C8 to begin charging through R15. Once C8 has charged to roughly 3.3V, the
comparator will switch states pulling the input of the inverter (U14A) high (thus switching the
invertors output low). This in turn pulls the threshold voltage of the comparator down to 1.6V,
ensuring that noise does not cause any false resets. This completes the reset cycle during power
up.
During power down, the opposite occurs, ensuring that the 8031 is held in a reset state
during power down as well. This is necessary in order to prevent random data from being written
into the SRAM during shutdown. Be aware that this can cause unusual unit lockups to occur if the
circumstances are just right. For example, if an MMT-8 was shut off while in record mode, it's
possible the 8031 was put into reset in the middle of writing a two byte pointer into memory. If only
one of those bytes is written before reset, then it may point to an incorrect location in memory
(battery backup holds the incorrect data). When the unit is powered back up, the incorrect pointer
may send the software into "never never land" where the only way to recover is to reinitialize the
unit.

3.20 Memory Mapped I/O

In order to easily control the vast number of hardware functions that the 8031 needs to
access, a system of memory mapped I/O is used. The basic idea is to make hardware functions
appear to the 8031 as unused memory locations. That way all that the software has to do is write to
an unused memory location in order to send that information to a specific device such as the LCD,
or keypad LEDs.
You Are Here

74HC138 (U13) performs the majority of the work in this circuit. Two things are
required before U13 becomes active. 1> A15 must be low (i.e. the 8031 is accessing the lower 32K
of address space). 2> The 8031 WRite line must be active (the 8031 is performing a memory write).
A15 is used to directly control which function (memory or I/O) is active.
Once U13 is enabled, addresses A8-A10 are decoded by it, and the latch corresponding to
the value of the decoded address is strobed. At this point, data on the 8031 data buss is "written"
into the latch.

4.00 Tape I/O

Tape output is very simple, while tape input is somewhat more complicated. This is due to
fact tape backup and tape sync have different requirements. It's important to remember that not all
tape decks are created equal. Probably the largest factor involved is the decks input and output
capacitances. These can greatly affect the signals sent to and from the deck, and may cause some
decks to be incompatible with the tape I/O needs of the MMT-8. However, these cases should be
rare, as the components chosen for the MMT-8 are based on the industry "standards" that most
manufacturers adhere to.

Alesis MMT-8 Service Manual 1.00 2

The tape output hardware is simply the 8031 output port P3.2 (pin 12), a pullup resistor
(R40), and a voltage divider (R39 and R39) for achieving a line level output. The output during tape
save or type sync out applications, will appear as a .5V pulse train, but only if the tape out is NOT
connected to a deck (the decks A.C. coupling will distort the output).

While we have heard many complaints regarding tape back up, we have actually found very
few actual tape failures. Most of the complaints arise from user error, so below is a list of successful
backup and tape sync strategies.

1. When attempting to save to a stereo cassette deck, use only the 1 channel (using both channels
may result in odd phase cancellations during playback).

2. Avoid using any noise reduction systems (i.e. Dolby, or DBX) as these can distort the timing of
the pulse train that contains the data.

3. Avoid using adapters for two reasons. 1> Some adapters contain built in attenuators that can
result in extremely reduced levels, both to and from the tape. 2> Oxidation and "wear and tear"
can cause adapters to become intermittent.

4. Always make several copies of each "save". It's especially smart to make copies on at least 2
different tapes as well. This reduces the chances that tape dropouts will cause loss of data.

5. Always use normal bias tapes, as high bias tapes actually end up recording noise, which could
make it past the wave shaping circuitry and cause false triggers.

6. Always verify tapes after saving them. This helps reduce the chances of bad saves. Note
however that the MMT-8 does not compare the tape to the contents of memory. It simply verifies
that the information on the tape is valid MMT-8 data.

7. Experimentation with record and playback levels usually lead to better results.

Trouble shooting tape problems should begin with listening to the data tape audibly. This can
help the technician determine if the problem occurs during tape save or load. If unusual dropouts
are heard then the problem is either just a bad tape, bad cable, or the tape save circuit. Normal
sounding tapes usually indicate a tape load problem. Only practice will help you determine what is
"normal".

5.00 MIDI I/O

The MIDI hardware is a standard implementation. MIDI out begins at the 8031's TXD port
(pin 11) and travels via R6 to the darlington pair Q1/Q2. Note that the 8031's internal pullup is not
very strong, and older units (revision A) may require the addition of an external pullup resistor for
the MIDI out to function correctly (see section 7.7).
MIDI in consists mostly of the opto isolator (U4), protection diode D6, pullup R7, and
threshold resistor R5. Note that the threshold resistor may need to be changed in order to eliminate
false MIDI triggers (see section 7.6).

6.00 Keypad Decoding

Keypad I/O is handled through a simple polling process Each row of the keypad matrix is
pulled low one at a time (via U14 which is memory mapped). If any button along the row is pressed,
the corresponding column input (U22) will appear high. If no buttons are pressed, all column inputs
will appear as a low. D9-D15 and R42-R47 provide protection for the outputs of U14. Use diagram 3
to localize individual button failures.

7.00 Metronome Output

8.00 Updates and Corrections

Alesis MMT-8 Service Manual 1.00 3

9.00 Troubleshooting

Alesis MMT-8 Service Manual 1.00 4

10.00 Software History

DATE VERSION COMMENTS

11/1/87 1.02 First production release

12/1/87 1.03 1) Fixes tape sync output so that when a part or song loops, a clock output pulse isn't

skipped.

2) Outputs MIDI controller 64 (sustain pedal) at value 0 (off) once for each MIDI
channel whenever a part or song is stopped so as to stop synths from sustaining.

3) Changed MIDI test routine so that an extra byte is sent out before testing MIDI to
accommodate 8051s that have indeterminate data in the UART on power up.
THIS VERSION WAS NEVER RELEASED.

12/8/87 1.04 1) Fixes STEP EDIT bug that caused erroneous data to be displayed if an event other

than the first or last event on a beat is moved to another beat.

2) Also in STEP EDIT, editing the sub-beats now do not allow decrementing below
beat 001/00.

12/16/87 1.05 1) Fixes cassette output bug that would occasionally cause a part to output data much

longer than it should, which would make the cassette interface data unusable.

12/30/87 1.06 1) Fixes cassette input bug that would cause data to be corrupted if only part 99 is

loaded in from tape.

1/4/88 1.07 1) Fixes cassette input bug that would cause part 99 to be erased if a single part or

song was loaded in, or a cassette was verified.

5/26/88 1.08 1) When in record on a part in loop, the display will no longer remain displaying

"RECORDING" after looping. The display will still not change when punching in or
out (to reduce delays).

2) Fixes bug that would cause an incorrect display if aborting "LOAD ONE PART"

before tape data has begun when previously in song mode, and aborting "LOAD ONE
SONG" before tape data has begun when previously in part mode.

3) Fixes bug that caused the display in part edit mode to show the incorrect beat

number for beats 456 through 511. This bug was also present in insert note (COPY
button) while in edit part mode.

4) Fixes bug that caused the display to lock up flashing between "CHANGE

LENGTH" & "MEMORY FULL" if an attempt was made to change the length of a
part when memory was full.

5) Fixes bug that would cause the end point of a track or part to be erased if part of a

track or part (i.e., only notes, controllers, MIDI channel 1, etc.) was erased. This
would not cause a problem while playing a part, but would result in the part following
this one in a song not to play.

6) Fixes bug that would cause any notes with durations of 2/64 or any multiple thereof

to be increased by 2/64. This would occur when changing length, quantizing, or
copying any part or track.

7) Increased delay loops in display routines so that fewer LCD displays would be

rejected in production.

Alesis MMT-8 Service Manual 1.00 5

3/8/89 1.09 1) If a song was stopped and continued within the first part of the song, the MIDI

output of the sequence would not always be in sync with the click, MIDI clock, and
display. This is now fixed.

2) If a track of a song was shifted by 2 or more 384th notes, and one or more of the

parts of the song was 1 beat in length, the first occurrence of a 1 beat part would be
played twice, causing that track to be delayed by 1 beat. This is now fixed.

3) Fixes bug in which if two events such as controller, program change, or aftertouch,

occurred on the same beat, and any edit operation was performed (such as ERASE,
QUANTIZE, LENGTH, etc.), then stepping backwards through this event in step edit
mode would cause non-existing events to show up in the display, which could cause
the machine to lock up.

4) Fixes bug which system exclusive data would be played back incorrectly if the

track with the data was set to any MIDI channel other than UNCHANGED.

5) Fixes bug in which events could be inserted into an empty track in step edit mode

repeatedly, until the events being inserted occurred before beat 1.

6) Fixes bug that would cause a song to continue from the wrong part if a step was

selected in edit mode and then STOP/CONTINUE was pressed.

7) When changing the name of parts or songs, the characters will no longer loop from

the last character (∅) to the first character (space) and vice versa.

8) Added feature that allows locating directly to any specific beat of a part. This is

accessed by holding either the fast forward or the rewind button, and entering a beat
number with the keypad. If in stop, pressing STOP/CONTINUE will continue the part
from the selected beat. If in play, the part will continue from the selected beat when
fast forward or rewind is released. In SONG mode, this feature can be used to locate
directly to any beat within the current step of the song.

9) Fixes bug that caused a track to stop playing if the track was shifted forward in

time (+1 to +48 384th notes), and the song was stopped during the last beat of a step,
and the track had already played the first beat of the next step. If continue was pressed
from this point, the shifted track would no longer play. This is now fixed.

7/22/89 1.10 1) If in song mode with the first step of a song being a one beat part, and rewind is

held until the display reads step 00 beat 000, and then stop/continue was pressed while
holding rewind, The first step would be played twice, and offset tracks may be out of
sync. Stop/continue is now ignored while holding the rewind button.

2) The start/stop footswitch jack is now scanned at power on to determine the polarity

of the switch that is plugged in (normally open or normally closed). For this to
function properly, the footswitch should be plugged in before turning the power on,
and it should not be pressed when turning the power on. If no footswitch is plugged in
at power on, the MMT-8 will assume a normally open footswitch.

3) If the start time of an unquantized note added to its duration results in the exact

beat that the note would be quantized to, performing a quantize note start would result
in a duration of 00/000 (e.g., note start of 001/47 duration 000/01 when quantized
would become 001/48 with a duration of 000/00), which is invalid, and could result in
a fatal crash if other notes existing on the same beat are edited. This is now fixed.

4) If a note event and a sysex event exist on the same beat, rewinding past the events

in step edit mode would cause the display to skip the sysex event, and only show the
note. If more than one note existed as well, the note preceding the sysex event would
also be skipped. This is now fixed.

5) In step edit mode, erasing a sysex event could cause a track to have erroneous data,

which could lead to a crash. This is now fixed.

Alesis MMT-8 Service Manual 1.00 6

6) In step edit mode, changing the start time of a sysex event forward would cause a

lock up and often complete memory dump. This is now fixed.

10/31/90 1.11 1) If an empty part is selected, Edit mode should not be able to be entered. However,

if an empty part is played, it is possible to enter Edit mode, stop playing, and then
insert events which will corrupt data. Now, Edit mode cannot be selected when
playing an empty part.

2) If an empty part is recorded for 683 beats (either by recording through the entire

part, or rewinding with loop on to a beat before 683 and punching in) without having
set the length first, the length of the part will not be set properly, causing eroneous
data in the Edit mode as well as other problems. This is now fixed.

3) If a part's length is changed from the top, any notes whose duration was a multiple

of 256 clocks (2beats/64sub-beats, 5/32, 8/00, etc.) will have its duration altered such
that the duration becomes 256 clocks (2/64) greater than it was previously. This is
now fixed.

Alesis MMT-8 Service Manual 1.00 7

11.00 MIDI Implementation

The following information is provided as a guide for programmers wishing to modify the data
received via MIDI from the MMT-8 for the purpose of interchanging parts from separate block dumps,
modification of part names, MIDI channel assignments, etc. Great care must be taken to insure that all
modified addresses are valid, since one incorrect value (the length of a part, for example) could result in all
data being lost in the MMT-8. These errors may not show up immediately, since the incorrect values may not
be accessed by the MMT-8 until a particular part or song is selected. Therefore, it is recommended that any
data manipulation programs be thoroughly tested after loading into the MMT-8 by selecting and recording on
many parts before assuming that the data is valid.

A system exclusive MIDI data dump from the MMT-8 is initiated by holding the TAPE button
down, pressing (and releasing) the PAGE DOWN button once, and then pressing the RECORD button. The
data sent out MIDI is in the following format:

HEX COMMENTS

F0H SYSTEM EXCLUSIVE STATUS BYTE
00H
00H
0EH ALESIS I.D. NUMBER
00H MMT-8 I.D. NUMBER

Following the above 5 bytes will be a block of data representing the contents of the MMT-8's memory. In
order to optimize the data transfer, 8 MIDI bytes are used to transmit each block of 7 MMT-8 data bytes. If
the 7 data bytes are looked at as one 56-bit word, the format for transmission is eight 7-bit words beginning
with the most significant bit of the first byte, as follows:

SEVEN MMT-8 BYTES:

0: A7 A6 A5 A4 A3 A2 A1 A0
1: B7 B6 B5 B4 B3 B2 B1 B0
2: C7 C6 C5 C4 C3 C2 C1 C0
3: D7 D6 D5 D4 D3 D2 D1 D0
4: E7 E6 E5 E4 E3 E2 E1 E0
5: F7 F6 F5 F4 F3 F2 F1 F0
6: G7 G6 G5 G4 G3 G2 G1 G0

TRANSMITTED AS:

0: 0 A7 A6 A5 A4 A3 A2 A1
1: 0 A0 B7 B6 B5 B4 B3 B2
2: 0 B1 B0 C7 C6 C5 C4 C3
3: 0 C2 C1 C0 D7 D6 D5 D4
4: 0 D3 D2 D1 D0 E7 E6 E5
5: 0 E4 E3 E2 E1 E0 F7 F6
6: 0 F5 F4 F3 F2 F1 F0 G7
7: 0 G6 G5 G4 G3 G2 G1 G0

In order to use the data properly, it must be decoded properly into MMT-8 byte format. The following list
gives the data locations within the "unpacked" (decoded) block of data, starting with the first byte of the
block being 000. NOTE: All absolute addresses must have an offset of 400H added to them (e.g., an
absolute pointer to a part that starts at 35AH should have the pointer value 75AH).

Alesis MMT-8 Service Manual 1.00 8