Retronetworking

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h1. BildTel 001

The Telekom-branded *BildTel 001* was likely the first commercially available ISDN video phone in Germany.

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(Only digital marketing picture I could find online, courtesy of Picture Allianze / Matthias Hiekel)

h2. Architecture

The system consists of the following parts:

* A TV screen with built-in [[BTX__Prestel__Videotex__Minitel|BTX]] decoder (inherited from [[LOEWE_Multitel_TV10]])

* A keyboard + phone-receiver combo (inherited from [[LOEWE_Multitel_TV10]])

* A _desktop-computer-like_ box called the Codec (containing the actual ISDN video telephony part, implemented by AEG/OLYMPIA)

* A video camera

The BTX Terminal [[LOEWE_Multitel_TV10]] was used as the "user interface" for the device, adding the _codec_ box to turn it into a video phone.

h3. Codec unit

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The Codec unit ("Bildeinheit") consists of a variety of different circuit boards:

* 1x power supply

* 4x "mainboards" stacked on top of each other (two sandwiches of two PCBA)

** boards have a number of DIN 41612 slots for plug-in cards

* 9x CODEC ADSP boards plugged into slots of the top two mainboards

* 1x OUTDIG sandwich, consisting of two PCBA plugged into slots of the top mainboard

** this is the TV output board, generating and digital-analog-converting analog TV signal

* 1x FIXME sandwich, consisting of two PCBA plugged into slots of a mainboard

** this is the camera input board, receiving and digitizing the analog TV camera signal

h4. AEG-OLYMPIA CODEC ADSP

This board exists 9 times in total. There are no visible differences between the boards; also the label on the GAL is identical.

PCB Marking: @1601914L11T@

Connector Marking: None

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|ADI ADSP-2101|Digital Signal Processor|

|VX-8111 10.0000 MHz|Crystal Oscillator|

|GAL20V8A (4012-001/2)|GAL|

|2x IDT 7201SA25J|FIFO|

|2x IDT 7202SA25J|FIFO|

|3xCY7C199-45VC|RAM|

* GAL image: attachment:bildtel001-aeg_olympia_codec_adsp_4012-001_2_GAL20V8A.jed

h4. AEG-OLYMPIA OUTDIG

PCB Marking: @2401913L1T@

Connector Marking: @35.103-3030.2 SN. 3051@

top PCBA:

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|Brooktree Bt101|Triple 8-bit VIDEODAC|

|Xilinx XC2018-100|FPGA 100 CLBs, 1000 Gates|

|S-Data SXO-300C 27.00000 MHz|Crystal Oscillator|

|3x IDT 7201SA25J|FIFO|

bottom PCBA: FIXME

h3. TV Camera

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h3. TV / BTX Unit

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h4. BTX decoder 

* EPROM image: attachment:bildtel001_tv10_btxdecoder_16772_074_349_27C010.bin

h3. Keyboard/receiver unit

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Actual Cherry keyboard PCBA after full disassembly, ultrasonic cleaning of all keycaps and lots of isopropanol on the PCB, removing what might be decades old coke residue:

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* EPROM image: attachment:bildtel001_keyboard_74E84.251U22g_1.0.0_010389_M2764A.bin

h2. Connections

h3. Codec unit

* connects to ISDN basic-rate S0 interface using 8P8C/RJ45 plug

* has two proprietary connectors for attaching video cameras

* has two SCART connectors (one for audio/video output to the TV)

* has a TAE jack for attaching an analog phone for the audio port (connected to the combined keyboard/receiver unit by default)

* has another TAE jack (purpose unknown)

* has a V.24 interface on a SUB-D 9 connector which connects to the built-in BTX decoder of the TV unit

h3. TV Camera

* connects to the Codec unit using a proprietary high-density connector that appears to carry both video and power

h3. TV unit

* has an RF input for TV broadcast signals (PAL)

* has a SCART input for baseband audio/video from peripherals (like the Codec unit)

* has a DIN speaker output for attaching an external speaker

* has a built-in BTX decoder with

** an unused DIN port intended to connect to the [[DBT-03]] BTX-Modem (not used in the ISDN video application)

** an unused centronics port

** an auxiliary V.24 port on a DIN connector interfacing the SUB-D 9 of the Codec unit

h3. Keyboard/receiver unit

* has a cable with TAE connector attached (connects to codec unit)

h2. Further Reading

* "Thread on the fediverse covering the BildTel 001":https://chaos.social/@LaF0rge/111317641831468838