Kimus 1a

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Participants CodeAsm, Erwin-c64, Webmind
Skills pots, electronics, voip
Status Active
Niche Electronics
Purpose Infrastructure

Turn an old coin(quarters only) operated payphone into a doorbell/art-project for the building.

Aquired an old 'Kimus 1a' aka 'PTT Sodeco TE 450'. This is an rotary-pulse-dial phone, the particular model seems to be one of the later ones and could be set to allow free calls.

The payphone will be connected to an old Fritzbox 7170 which functions as an ATA to connect to the VOIP-server. With this it can make and receive calls.

The VOIP-server will then redirect calls to spaces/renters in the building, it will only allow internal calls, or atleast no calls that cost money. 112 will be disabled to prevent prank-calls and due to reliability problems.


The machine did not come with a key, but it was opened by lockpicking.

Coin Mechanism

This part will not be used in operation and is here only for documentation purposes.

  • Validation is done mechanically by size and weight, by this mechanism: Kimus1 0010.jpg
  • The coin return button will return coins from this mechanism to the user
  • When validated it will move towards the coin tracking system: Kimus1 109.jpg
  • The PCB can be seen on: Kimus1 0102.JPG and Kimus1 0103.JPG

Cointracker PCB

The two IC's are an MC14007UB and a MC14584BCL, seemingly dated on 1983.


Mainboard PCB

The main board has a 27 single sided edge connetor, where the first 12 half is on the top and the remaining 15(!) on the bottom. Pin 13 is a key hole (on the mating connector is a pin missing

The following IC's are on the board

  • MC14503BCL: Hex Non-Inverting 3-State Buffer (datasheet)
  • MC14017BCL: Decade counter (datasheet)
  • MC14013B: dual type D flip−flop (datasheet)
  • MC1413L: High Voltage, High Current Darlington/Seven-Line Power Driver (datasheet)
  • MC14042BCL: Quad Transparent Latch (datasheet)
  • MC14049UB: Hex buffer/inverter (datasheet)
  • MC14093BCL: Quad 2-Input NAND chmitt Trigger (datasheet)
  • HCMP1824D: Hughes Type HCMP 1824 wafers (32 x 8 Static RAMS)?posible (datasheet)
  • cd4047BCJ: Low power monostable / astable multivibrator (datasheet)
  • CDP1802CD: RCA 1802 Microprocessor (wikipedia, datasheet) more datasheets
  • CDP1833CD: Mask Programmable ROM? (datasheet)


Dumping the ROM

Mainboard layout

There is no layout made yet for this board but an example for the 1802 MCU was located in the DC1833 Rom datasheet. Example system layout Inside the RCA MCU datasheet itself there is also an example available

rom dumping:


The mainboard has four plugs with plastic keys that resemble numbers. On this board there are use a "0"(zero), "1", "2" and "5". actualy they have 4 metal strips that can connect to a mating pin that with the other 3 plugs forms a 4bit like setting. There is a sticker that somewhat describes what these should mean. Its asummed that the lower left one describes: "Toesalg" in 5 cents increments The lower right: "min. inworp" means minimal change. The original setting was 0, 1 (zero toeslag, 1 coin to start), it was changed to say something like "zero starting fee, 1 coind for extra minutes" thus by experiment it resulted in free calling. Note, the phone does not recieve minutes signals, so the "toeslag" cant be applied or something (sorry my english: codeasm)

These "keys" have special shapes to form a indication of their value. It has been suggested that we could decode the meaning. We should take some detailed pictures of their shape.


The interconnections between the different boards.

Bell & Dial system




Known issues

  • The ring-power from the fritzbox is rather low, due to this the bell isn't too audible.
  • The lock needs to be replaced as we don't have a key for the device.

See Also