The next major task was a further development of the Beocord 8000, called Beocord 9000. The many new features required a significant extension of the Intel 8049 program from the Beocord 8000. Unfortunately, the 4K ROM available in the 8049 and 8355 combination were almost all used up, and since an 8049 only has a 12-bit address counter it can address at most 4K.
The solution was an additional 8355 ROM and I/O circuit, which provided both additional input/output pins as well as 2K additional ROM for program memory. An output pin on the 8049 was connected to chip select on one 8355 and inverted to chip select on the other. Thus only one 8355 and only 4K was active at any given time. A disadvantage of this arrangement is that a jump or call instruction from a function in one 8355 to a function in the other always had to be made via the 8049, which then selected the destination 8355 before the onward jump was made. A similar procedure had to be followed for a return from a subroutine in one 8355 to the call location in the other. It was of course necessary to minimise the number of such calls.
The Beocord 8002 had meanwhile been launched with Dolby HX Pro as almost the only difference from the Beocord 8000. The program was the same in both versions. Dolby HX Pro was patented by B&O with Jørgen Selmer Jensen as inventor. He was also the developer responsible for the electronics in the Beocord 9000.
The most significant change in the Beocord 9000 compared to the Beocord 8002 was Computer Controlled Calibration (CCC), which could measure a given tape’s recording characteristics and optimise recordings on the tape. There were three main types of cassette tapes, called iron, chrome, and metal. The recording characteristics of these three are quite different from each other and also vary between tapes of the same type from different manufacturers.
The Beocord 9000 detects the tape type from holes in the bottom of the cassette and has a REC CAL (Record Calibration) function that records some pulses with different settings and measures the result of the recordings to find the optimal settings. REC CAL will also detect if the tape type is encoded correctly in the cassette and will select the correct type regardless of the cassette encoding. The calibration codes are recorded approximately one minute from the start of the tape to bypass the lead-in tape and avoid bad spots that may occur at the start of the tape.
The parameters measured and adjusted are:
1. bias in the right channel to ensure linear response in the range from 333 Hz to 7 KHz. Bias can be changed in 0.5dB steps.
2. bias in the left channel, as for the right channel.
3. sensitivity at 17 KHz, so it records at the same level as 333 Hz to 7 Khz.
4. sensitivity at 333 Hz at -20 dB on peak pulse meter display.
5. distortion set to about 2% at 333 Hz and 0 dB input level.
After calibration, the unit is ready for recording. It is also possible to store the measured parameters for each of the three tape types, which will then be used each time a tape of that type is inserted where calibration is not performed. If you normally use tapes of the same make, this will save time each time you insert a tape or when you want to record on a tape that has previously been partially recorded. The values are stored in a 16×16 bit CMOS RAM, which is kept alive by a lithium battery when the unit is not connected to the mains. The values can also be read out on the display, allowing the user to see if a particular tape has parameters that are outside the normal range.
The recording and playback heads of the Beocord 9000 are in a single integrated unit, and due to crosstalk between the two interconnected heads, it is not possible to record and play back simultaneously. For the calibration measurements, a tone is first recorded for a given time, the recording head is then switched off and playback started for reading the recorded tone. The next parameter value is selected if necessary, and the process is repeated until the corresponding parameter is set correctly. The distance between recording head and playback head gives a transport time of about 90ms at recording and playback speed. A signal is recorded for about 100ms, and when recording is stopped the program waits about 15ms before the playback head reads the recorded signal and checks whether the next step should be selected or whether it has found the optimal setting. The whole calibration can be completed in about 10 seconds.
A much more comprehensive description of the process is found in the Beocord 9000 white paper, Understanding Beocords II Beocord 9000.
A more comprehensive description of the development process and program structure can be found in an article I wrote for the journal Elektronik, December 1982. The article in Danish has been scanned from the magazine, and converted by OCR from the scanned copy and then translated.
The original specifications for type number 4810, which became Beocord 9000, written by Bent Hyldgaard who was project manager on both Beocord 8000 and Beocord 9000, are also attached. The operation of the final unit was changed during the development process, so it does not quite match the specifications. The document has some of my handwritten notes.
Beocord 9000’s recommended retail price in February 1982 was 9,595 kroner.
Bang & Olufsen’s brochure Oplevelser for 1983/1984 has a very glowing description of the Beocord 9000 (translated from the Danish original).
Beocord 9000. The Stradivarius of tape recorders.
It’s with musical instruments as with tape recorders. There’s always one that sounds better than the others.
This is true of Antonius Stradivarius’s violin. And that goes for Bang & Olufsen’s unique, easy-to-operate Beocord 9000 tape recorder.
Beocord 9000 adapts to the music as it is recorded, so that the reproduction is an exact copy of the original. At the same time, Beocord 9000 adapts to the technical capabilities of each tape. So for the first time, recordings can be made in complete harmony with both music and tape.
Get the best out of your tapes. In 10 seconds.
At the touch of a button, the Beocord 9000’s computer-controlled calibration system measures all the tape’s technical capabilities and automatically optimises the recording. Calibration also includes tape type and length.
All within 10 seconds.
It’s easy, hassle-free operation that ensures recordings of the highest standard.
HX Professional and Dolby C. For the music lover.
Beocord 9000 has a built-in HX Professional recording system. A patented Bang & Olufsen invention. It’s a revolutionary system that automatically ensures even the highest, finest tones are captured on tape. Recording becomes “higher ceiling” (HX = Headroom Expansion). Regardless of tape type. And the cheaper the tape (e.g. Ferro), the greater the benefit.
Once the music is recorded on the Beocord 9000, you can enjoy the exquisite result on any tape recorder.
On top of that, Beocord 9000 is equipped with the new Dolby C noise reduction system, which lowers tape noise to well below audible levels.
Advanced technology that’s easy to live with.
Beocord 9000 is designed for systematic recording.
The computer memory can store the calibrated data as long as you use the same type and brand of tape.
Tape consumption is measured in minutes and seconds, and with a single touch you can see how much tape is left. And 5 minutes before the tape runs out, Beocord 9000 tells you that it’s almost over.
The search system is also based on minutes and seconds. Enter the desired time and Beocord 9000 will automatically find the right place on the tape. Silently and within seconds.
The optimum.
Beocord 9000 stands alone among the world’s tape recorders. But works perfectly with any of our Hi-Fi music systems. And it will raise any music system above the crowd. No matter the brand or size.
Next chapter: Various later products
The article Microcomputers in consumer products from the December 1982 edition of Elektronik magazine after OCR conversion to Danish text and then translated to English with the assistance of the translator at DeepL.com.
There were numerous reviews of Beocord 9000 in magazines. Most of these reviews were very positive. The following PDF files, scanned from poor quality photocopies, are from English-language magazines.
Microprocessors in B&O consumer products 