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In 1975 gab es eine letzte Anzeige für einen CD-4 Bausatz

Ein CD-4 Bausatz von einem kleinen Computer- Bausatz-Hersteller aus 1975

Hier bei uns in Deutschland war das Computer Fieber aus- gebrochen und mein Kommilitone Rudi hatte solch einen gekauft. Es war ein Motorola 6809 basierter Bausatz aus Amerika (vom deutschen Wohnzimmer-Importeur aus Frankfurt) von einer kleinen Bausatz-Klitsche mit Namen "SWTPC" "Southwest Technical Products". Und  das Teil kostete über DM 2000.-. Ich weiß noch, daß die Zusatz-Platine mit dem statischen RAM (8 KB - kilobyte - Haupt- speicher) mt einer riesen Anzahl von kleinen gesockelten Chips über 800.- DM gekostet hatte.

Ich hänge hier erst mal die Computer-Anzeige von Dezember 1975 ein:


SWTPC 6800 - The Computer System You Hove Been Waiting For

A BENCHMARK SYSTEM - Using the MOTOROLA M6800 benchmark microprocessor family.

"Southwest Technical Products" is proud to introduce the M6800 computer system. This system is based upon the Motorola MC6800 microprocessor unit (MPU) and it's matching family of support devices.

Ein toller Computer aus 1975

The 6800 system was chosen for our computer because this set of parts is currently in our opinion the "Benchmark Family" for microprocessor systems.
It makes it possible for us to provide you with a computer system having outstanding versitility and ease of use.

In addition to the outstanding hardware system, the Motorola 6800 has without question the most complete set of documentation yet made available for a microprocessor system. The 714 page Applications Manual for example contains material on programming techniques, system organization, input/output techniques, and more.

Also available is the "Programmers Manual" which details the various types of software available for the system and provides instructions for the programming and use of the unique interface system that is part ol the 6800 design.

The M6800 system minimizes the number of required components and support parts, provides extremely simple interfacing to external devices and has outstanding documentation.

Der Inhalt des Bausatzes :

Our kit combines the MC6800 processor with the MIKBUG® read-only memory (ROM). This ROM contains the program necessary to automatically place not only a loader, but also a mini-operating system into the computers memory. This makes the computer very convenient to use because it is ready for you to enter data from the terminal keyboard the minute power is turned "ON".

Our kit also provides a serial control interface to connect a terminal to the system. This is not an extra cost option as in some inexpensive computers. The system is controlled from any ASCII coded terminal that you may wish to use. Our CT-1024 video terminal is a good choice. The control interface will also work with any 20 Ma Teletype using ASCII code, such as the ASR-33, or KSR-33.

The main memory in our basic kit consists of 2,048 words (BYTES) of static memory. This eliminates the need for refresh interrupts and allows the system to operate at full speed at all times.

Our basic kit is supplied with processor system, which includes the MIKBUG ROM, a 128 word static scratch pad RAM, and clock oscillator bit rate divider; main memory board with 2,048 words, a serial control interface, power supply, cabinet with cover and complete assembly and operation instructions which include test programs and the Motorola Programmers Manual if you have a Motorola 6800 chip set, we will sell you boards, or any major part of this system as a separate item.

If you would like a full description and our pricelist, circle the reader service number or send the coupon today. Prices for a complete basic kit begin at only US$ 450.00.

  • Anmerkung : Nach ein paar langen Monaten hatte ich auch solch einen 6809 Computer mit 16 Kilobyte RAM, einem grünen Bildschirm und zwei Floppylaufwerken mit 180 kByte Floppies und machte meine ersten Gehversuche in Basic. Rudi programmierte bereits in Assembler, doch das war für mich 3 Nummern zu hoch.


und ein paar Seiten weiter diese "merkwürdige" Anzeige .....

Für uns Hifi-Fans war zum Ende 1975 Anfang 1976 (analoges) Quadro mit allen drei Varianten bereits tot, weil es keine (oder besser nur ganz ganz wenige teure) wirklich überzeugenden Aufnahmen gab. Und SQ-Quadro Platten auf dem Stereo-Plattenspieler, auch auf den besten Thorens TD 125 MKII, hörte sich nicht gut an. Die QS/SQ Decoder taugten offensichtlich gar nichts und an CD-4 mit der Shibata Nadel trauten wir uns wegen der exorbitanten Preise nicht ran. Auch behandelten die Kritiken in den Audio Magazinen fast nur die Demo-Schallplatten der Hardware-Anbieter.


SWTPC CD-4 DEMODULATOR Kit (October 1975)


    Southwest Technical Products is proud to offter the most advanced CD-4 demodulator available. Our new CD-4 has characteristics superior to anything previously available thanks to the QSl-5022 integrated circuit used in the unit.

  • This IC and the balance of the circuit was designed by Ouadracast Systems Inc. under the direction of Mr. Lou Dorren.

  • The Demodulatur-Kit QSI-5022 contains all the sub-system functions needed to demodulate a CD-4 disc, from the phono cartridge input amplifiers to the output drive for the four power amplifiers. It may be used with either an RIAA equalized magnetic cartridge (Abtaster), or a semiconductor cartridge with flat equalisation.
    Now anyone can afford to add discrete true 4 channel sound to their system. You no longer need be satisfied with matrix techniques that produce acoustrical enhancement, but not true 4-channel sound. The Southwest Technical Products CD-4 demodulator when added to your system will produce four channel sound from a CD-4 encoded disc that will equal, or surpass anything you can buy - no matter what the price.
    The SWTPC demodulator connects between the cartridge and the volume-tone control portion of your system. If you did not want tone controls, actually all that would be needed in addition to our CD-4 demodulator would be volume controls for the from and rear amplifiers. The demodulator is self powered from any 115 Volt 60 Cycle line. When normal stereo discs are played on your system a muting system automatically turns off the rear channels. A manual override 2 or 4 channel selector switch is provided on the rear panel.
    As shown in the photograph, the vast majority of the parts mount on the epoxy-fibregtass circuit board. Part numbers and package outlines printed on the top of the board make proper assembly quite simple. Anyone with a minimum of electronic experience should be able to assemble this project without any problems. A copy of the article describing the CD-4 demodulator and assembly instructions are supplied in the kit.

  • CD-4 Demodulator Kit QSI-5022 ......... $60.00 ppd



For those who do not already own a CD-4 cartridge, we are offering the "Technics" EPC451C semiconductor strain-gauge cartridge at a special low price when purchased with our new CD-4 demodulator kit. This cartridge features a Shibata-type stylus and excellent response out to 50 kHz. This eliminates any chance of "carrier drop-out", or "carrier crosstalk" which result in abnormal noise or distorted sound The EPC-451C produces a high output (about 30 times that of an average magnetic cartridge! and does not pick up hum from magnetic, or electrostatic fields. Easily replaced stylus.

EPC-451C CD-4 Cartridge ........ $ 25.00 ppd

Achtung : (Those "semiconductor pickup" cartridges were made by Technics By Panasonic. It is neither MM nor MC nor ceramic/piezoelectric, it is special. And you need a special Panasonic /Technics preamp !).


Lou Dorren has recorded a special test record for "Southwest Technical Products Corp." that will allow you to properly adjust your CD-4 demodulator for the best possible sound. This special test and demonstration record is yours for only $ 5.00 when purchased with the CD-4 demodulator kit.

CD-4 Test Record .......... $ 5.00 ppd


Send the coupon below and add $ 0.50 and we will send you by return mail a copy of the article describing our new CD-4 kit along with our catalog of other Kit projects.

Sucht man nach Louis Dorron, so findet man dies :


Louis Dorren and CD-4 in the 1970s - (1948 – Oct. 2014)

In 1973, Dorren was working with Jac Holzman, president of Elektra Records, in relation to the CD-4 system and its relationship to the records. In an interview Holzman said that Lou had built him a demodulator, and Holzman, who had previewed others said that, Lou's was the best he'd heard.

In the mid 1970s, CD-4 demodulator kit was offered by "Southwest Technical Products". It was designed by Dorren. Also offered was an optional Technics EPC-451C cartridge and a test record he had recorded for Southwest Technical Products. Readers of the Popular Electronics magazine in which the items were advertised could send away for them.

In 1974, Dorren was at a party with his fiancé Nancy Bostic. Other guests included Claude Hall from Billboard Magazine, Casey Casem, and Tom Rounds. Dorren had a chance to demo his IC chip CD-4 Discrete Quadracast Systems demodulator. At that time there were only two of them in existence. And only a few people had heard them in action.


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