Organ Service Corporation

TOS and Divider IC's

 

Your source for hard-to-find Top Octave Synthesizer (TOS) ICs and obsolete and hard-to-find Divider ICs.

All IC's are shown with pin-outs and Retros are shown with board layout as well as pin-out diagrams.

TOS/Divider INDEX

Top Octave Synthesizer (TOS) IC's

Order
Description																							
Type
Figure
KS-82
13-Note Top Octave Synthesizer
MO82B
 Figure 4
KS-83
13-Note Top Octave Synthesizer
MO83B
 Figure 5
KS-86
12-Note Top Octave Synthesizer
MO86B
 Figure 6
KS-87
12-Note Top Octave Synthesizer
MO87B
 Figure 7
KS-196
12-Note Top Octave Synthesizer
AY-3-214
 Figure 8
KS-MDD
Dual TOS/MDD Retro for Hammond MDD Generator Boards			
S2555/S2556
 Figure 3
KS-C1
Dual TOS Retro for Conn Organs
S2555/S2556
 Figure 2 
KS-G1
Dual TOS Retro for Gulbransen Organs
S2555/S2556
 Figure 2
KS-L1
Dual TOS Retro for Lowrey Organs
S2555/S2556
 Figure 2 
KS-T1
Dual TOS Retro for Thomas Organs
S2555/S2556
 Figure 2 
KS-813-1
7-Note Top Octave Synthesizer
S2555
 Figure 1
KS-813-2
6-Note Top Octave Synthesizer
S2556
 Figure 1a

 

Frequency Dividers IC's

Order
Description
Type
Figure
KS-4040
Single Spider Divider IC
MFC4040
 Figure 9 
KS-6020
Dual Independent Spider Divider IC
MFC6020
 Figure 10 
KS-6050
Dual Cascaded Spider Divider IC
MFC6050
 Figure 11 
KS-180
7-Stage Divider Retro IC
SAJ180
 Figure 12 
KS-455
6-Stage Divider Retro IC
PD455
 Figure 13 
KS-1007
7-Stage Divider IC
AY-1-1007
 Figure 14 
KS-3216
6-Stage Divider Retro IC
LM3216
 Figure 15 
KS-5823
6-Stage Divider Retro IC
MM5823
 Figure 16 
 

All About the Eternal Top-Octave-Synthesizer-TOS IC's

By Jim Duane

TOS chips (Top Octave Synthesizer) have been one of the mainstays of the organ industry throughout the organ heydays of the 1970's. The majority of the organs in existence today were produced during the rapid growth decade of the '70's. The TOS chips produce the top twelve musical notes which are then divided by a series of divide-by-two chips or keyer LSI's to provide the multiple octaves required to generate all the notes on a given organ model. The TOS chips replaced the twelve individual oscillator/divider circuits previously utilized by the organ industry in the 1950's and 1960's.

TOS Divisor System

The TOS chips require only one oscillator frequency, usually 1 MHz to 2 MHz. this high frequency signal supplies the clock frequency which is then divided by the TOS chips into the twelve equally tempered top octave musical notes of the scale. The twelve divisor ratios are multiples of the twelfth root of two which is 1.05946. This means that the equal interval between successive notes of the musical scale are separated by the ratio of 1.05946 to 1. For example, 2 MHz divided by 478 results in a frequency of 4186 Hz which is a C5 note, usually designated as C5 or the first note of octave five, the highest octave on a standard 5 octave, 61 note keyboard. The next note C#5, then would be 4186 Hz x 1.05946 which equals 4434.9 Hz (C#5). This is equal to the 2 MHz clock being divided by 451. This progression continues up to B5 which is a divisor ratio of 253. To produce C6, the highest note of 61 on a 5 octave keyboard, a thirteenth divisor ration of 239 is required. Most of the TOS chips actually have a 13 divisor ratios. If a TOS with only 12 divisor ratios is utilized, the chip produces C#5 through C6. C5 is derived by sending the C6 note (8362 Hz) into a divide-by-two chain within the IC. This divides the 8362 Hz in half which is note C5 (4186 Hz). All lower octaves use a succession of divide-by-two "divider" chips to produce all the necessary octave notes for a given instrument. The most common "divider" chips that were used by organs and synthesizers are shown in Figures 9 through 16, (see the TOS Index above).

Dual 6-Note and 7-Note TOS IC's

The first TOS IC's to be utilized in organs in the early 1970's were actually two IC's The first IC produced 7 of 13 top octave notes and the second IC produced the remaining 6 top octave notes. These dual chips, the S2555 and S2556, used by manufacturers such as Gulbransen, Hammond, Lowrey, and Thomas are shown in Figure 1. These chips ran hot and required three supply voltages, a positive voltage and two negative bias voltages as well as ground. The output signals were at a level between the positive voltage supply voltage and ground. Both chips used the same 2 MHz clock input, which was divided by the appropriate ratios to produce the top 13 notes. 

The Conn Organ Company also used dual TOS chips in selected models, but they chose a slight variation of the TOS S2555 and S2556 chips. These chips appear to be in the same format, but the divisor ratios are different. The MM5555 TOS, employing a 2 MHz input clock, actually would produce notes B5 through B6. Therefore, the S2555/S2556 and the MM5555/MM5556 IC pairs can not be intermixed. However, the MM5555/MM5556 TOS pair may be used to replace a S2555/S2556 TOS pair if the input clock frequency is increased by the ration of 1.05946, that is, from 2 MHz to 2.126 MHz. For example in an organ with a 2 MHz clock utilizing a S2555/S2556 TOS pair, if the S2555 failed and was replaced with a MM5555, the organ's top octave would have two F# notes and no C notes. If the S2556 failed and was replaced with a MM5556, the organ's top octave would have two C notes and no F# notes; both situations would be totally unacceptable.

Dual TOS Retros

The actual S2555 and MM5556 chips are no longer available; however, Keyboard Systems designed and Organ Service Corporation now produces retro IC's that directly replace the original TOS chips. Organ Service Corporation manufactures a retro S2555 TOS using 7 outputs of a 12-Note TOS with a divide-by-two chip mounted on a small board using two rows of header pins that plug directly into the TOS's 14-pin socket or PCB mounting holes. See Figure 1. Organ Service Corporation has a similar retro for the MM5556, which means that both these 6-Note and 7-Note TOS IC's will be available in quantity for years to come. These retros have an advantage over the original IC's in that they require only a single positive supply voltage. The retros draw lower current and eliminate the need for negative bias supply voltages. Organ Service Corporation also produce a retro board that replaces both of the older 7-note and the 6-note TOS IC's. Figure 2 displays the retro board which can be used in several organs including Conn, Gulbransen, Lowrey and Thomas. Hammond uses a specialized version as shown in Figure 3. The Hammond retro board replaces several components making the Hammond MDD Generator boards more reliable.

13-Note TOS IC's

In the mid 1970's the dual 6-Note and 7-Note TOS IC's were replaced with a single 16-pin TOS IC, which is a 13-Note TOS. These IC's were utilized in thousands of organs produced by Baldwin, Conn, Gulbransen, Hammond, Kimball, and Lowrey. These TOS IC'S were the MK50240, S50240, and MO83B types. See Figures 4 and 5. Both MO82 and the MO83 are the same except the MO82 has a 30% output duty cycle and the MO83 has a 50% output duty cycle. These single TOS IC's draw considerably less current, ran cool and needed only a single positive voltage supply. The 13-Note TOS IC's are in short supply from most organ manufacturers; however, Organ Service Corporation has a large supplies of these TOS IC's.

12-Note TOS IC's

While the U.S. manufacturers were using the 13-Note TOS, the European manufacturers, i.e. Gem, Eminent, Farfisa, and Wersi utilized similar 16-pin TOS's, the MK50242, S50242, MO86B or MO87B. These chips differed in that they produced 12 outputs instead of 13. They incorporated the 12 notes of the musical scale, but do not produce two C notes like the 13-note TOS IC's. The MO86 type, see Figure 6, and the MO87 type, both have the same 12-note pin-out; however, the MO87 type, see Figure 7, requires a negative bias supply on pin 9. With a 2 MHz clock input, these 12-Note TOS's produce C#5 through C6. In order to produce C5, a separate divide-by-two IC must be utilized to provide note C5. Both of these TOS IC's are very scarce in the U.S. However, Organ Service Corporation has a limited supply of these chips.

Specialized Types

A specialized format TOS, the AY-3-0214 type, has the same 12-Note pin-out as the MO86/MO87 types, but the AY-3-0214 is unique in that the divisor ratios are twice that of the commonly used 12-Note TOS chips. See Figure 8. The AY-3-0214 TOS, as far as it is known, is only utilized in several models of Wurlitzer organs, i.e., the 625, 630, and 950 series. The original AY-3-0214 TOS is no longer available, however; a retro has been developed which is available from Organ Service Corporation and Morelock's Organ Parts.

Other Uses

In addition to producing the top octaves in organs and synthesizers, these TOS chips are also used by model railroaders for train whistles and by hobbyists to build various types of alarms, sirens and multiple tone decoders. If all the 12 or 13 outputs of a TOS chip are added together, the combination of all twelve notes produce a very good white noise generator. Lowrey utilizes this approach to synthesize snare and brush voices in its G series organs. By adding tailoring resistors, the tonality of the noise output can be controlled. This produces more realistic sounding brush or snare voicing than that which is derived from using a random noise generator such as the MM5837 IC.

Summary

The 6-, 7-, 12-, and 13-Note TOS IC's comprise the main note generation systems in several hundred thousand organs which were produced during the 1970's. If these IC's fail in an organ or synthesizer, the entire note generating system is dead. These TOS IC's are a vital component of the organ and synthesizer industry and will be in demand for at least the next twenty years.


TOS Types and Manufacturers' Part Number Listing

 13 NOTE TOS

Generic MO83, 50240, 50241 See Figure 5
Arp
1405701
Baldwin
514-100547
Baldwin
514-060260
Conn
72469-001
Fender
301411-901
GEM
10316, 10318
Gulbransen
80400
Hammond
075-00210
Hammond
075-000220
Hammond
J319-001003A
Hammond
J319-001014
Hammond
J319-001015
Kimball
552-003-000
Kimball
552-027-000
Lowrey
991-027326-000
Rodgers
1415-010
Wersi
630.102
 

12-NOTE TOS

Generic MO86, 50242 See Figure 6
GEM
10250, 10253
GEM
10305, 10317
Farfisa
W1105, W1111
Kimball
411CIN0480
Kimball
411CIN2860
Thomas
13-5069-6
Thomas
13-5076-6
Wersi
630.104
Wurlitzer
142164, 142168
Wurlitzer
144158, 144164
 

12-NOTE TOS

Generic MO87 See Figure 7
Conn
72603-001
Eminent
436.0087
Wersi
630.103
 

12-NOTE TOS

Generic AY-3-0214 See Figure 8
Wurlitzer
147196
 

7-NOTE TOS

Generic MM5832, S2555 See Figure 1
Gulbransen
801817
Hammond
075-047242
Hammond
J319-001005
Hammond
J319-001017
Lowrey
991-018813-001
Thomas
13-5055-6
 

7-NOTE TOS

Generic MM5555, MC1183L
Conn
72147-001
Conn
72147-101
 

6-NOTE TOS

Generic MM5833, S2556 See Figure 1a
Gulbransen
801816
Hammond
075-047243
Hammond
J319-001006
Lowrey
991-018813-002
Thomas
13-5056-6
 

6-NOTE TOS

Generic MM5556, MC1184L
Conn
72147-002
Conn
72147-102

 

Note: Prices listed below are Retail Prices. Discounts are available to qualified Service Centers.



Figure 4

Description: 13-Note Top Octave Synthesizer IC
30% Duty Cycle Output



Order: KS-82
Cost: $39.95

Figure 4
Back to Index






Figure 5

Description: 13-Note Top Octave Synthesizer IC
50% Duty Cycle Output



Order: KS-83
Cost: $39.95

Figure 5
Back to Index






Figure 6

Description: 12-Note Top Octave Synthesizer IC



Order: KS-86
Cost: $39.95

Figure 6
Back to Index




Description: 12-Note Top Octave Synthesizer IC


  • Generic
  • MO87B
  • MC86B1
  • ECG-2043





Order: KS-87
Cost: $39.95

Figure 7
Back to Index




Figure 8

Description: 12-Note Top Octave Synthesizer Retro
Same pin out as the MO86B except the output is one octave higher. Used by Wurlitzer.

Order: KS-196
Cost: $69.95

Figure 8
Back to Index




Figure 3

Description: Replacement Dual TOS/MDD Retro For Hammond MDD Generator Boards. Replaces All IC's, plus several other components on the 124-265, 124-266, 124-318 and MG-2 MDD Generator Boards. NOTE: The KS-MDD will only work in models using the MDD boards listed. It will not work with any other models, including the Hammond models built in Japan.

Order: KS-MDD
Cost: $85.90

Figure 3
Back to Index


Figure 2

Description: Replacement Dual TOS Divider Retro For Organs Using Dual TOS IC's. This retro replaces both the 7-note and 6-note TOS IC's.

Note: This retro will not work as a replacement for the TOS in the Japanese built Hammond Organs

Figure 2
Back to Index



Description: 7- Figure 1Note Top Octave Synthesizer IC Retro

Note: This retro will not work as a replacement for the TOS in the Japanese built Hammond Organs

Generic
S2555
MC1183L
MM5832
(Not Compatible
with M5555)

Order: KS-813-1
Cost: $55.90

Figure 1

Back to Index





Description: 6-Note Top Octave Synthesizer IC Retro

Note: This retro will not work as a replacement for the TOS in the Japanese built Hammond Organs

Generic
S2556
MC1184L
MM5833
(Not Compatible
with M5556)


Order: KS-813-2
Cost: $55.90

Figure 1a
Back to Index





Figure 9

Description: Single Spider RTL Divider IC

Order: KS-4040
Cost: $3.00

Figure 9
Back to Index



Figure 10

Description: Dual Spider RTL Divider IC Dual
With Independent Dividers

Order: KS-6020
Cost: $9.00

Figure 10
Back to Index


Figure 11

Description: Dual Spider RTL Divider IC Dual
With Cascaded Dividers

Order: KS-6050
Cost: $19.90

Figure 11
Back to Index




Figure 12

Description: 7-Stage Divider Retro

Generic
SAJ-180
AY-1-5050
SA1005
TMS3612




Order: KS-180
Cost: $25.90

Figure 12
Back to Index




Figure 13

Description: 6-Stage Divider Retro

Generic
PD-455
PD-474
PD-492
MC1180L
MM5554
MM5824


Order: KS-455
Cost: $25.90

Figure 13
Back to Index




Figure 14

Description: 7-Stage Divider IC



Order: KS-1007
Cost: $19.90

Figure 14
Back to Index





Figure 15

Description: 6-Stage Divider Retro



Order: KS-3216
Cost: $24.95

Figure 15
Back to Index





Figure 16

Description: 6-Stage Divider Retro





Order: KS-5823
Cost: $25.90

Figure 16


Organ Service Corporation
190 East Washington Street
Marengo, IN 47140
Phone: 800-457-4408 - Fax: 812-365-2208
Email:
custsvc@organservice.com

Home Page

Copyright  2001 Organ Service Corporation.  All Rights Reserved.

 

Last updated: