Kansas City Standard

Kansas City Standard ( KCS), or byte standard is a digital data format for audio cassettes, which can be written and read with a simple tape recorder.

Genesis

The American magazine Byte supported in November 1975 a symposium in Kansas City, Missouri ( USA), on which a standard for storing digital data should be developed at low cost audio cassettes. At the time, cost floppy drives more than DM 3000, -.

The 18 participants of the meeting agreed on a system whose design was referring to a proposal by Don Lancaster, which was described in the first issue of Byte Magazine. After the meeting the standard of Lee Felsenstein ( Processor Technology ) and Harold Mauch ( Percom Data Company) was written.

In February 1976, the Byte Magazine reported the Symposium and in March published two circuits of the cassette interface by Don Lancaster and Harold Mauch. The data rate of 300 baud was slow but reliable ( loading an 8 kilobyte BASIC interpreter took five minutes). Most tape recorder at that time could already operate at higher data rates.

Description of the standard

A cassette interface works on the same principle as a device connected to a serial port modem. The digital 0s and 1s from the serial port are converted into sound. It comes here the principle of Frequency on the application. A '0 ' is complete waves of a 1200 Hz sine wave and a '1 by four ' represented by eight complete waves at 2400 Hz. This results in a data transfer rate of 300 baud.

Before the data transfer on the tape must be stored for at least 30 seconds, the carrier frequency (2400 Hz); this is to support a synchronization of the cassette interfaces with the tape recorder.

Each packet of data begins ( LSB first, so significant bits ) followed by a start bit ('0 '), then the up to eight data bits. Is completed, the data packet with two stop bits ('1 '). Each data packet has thus 11 bits; the data rate is 27 bytes per second.

The data packets are transmitted in blocks, the block length must be at least 5 seconds. The structure and the size of the blocks is not defined.

1200 baud variant

The company Acorn Computers Ltd implemented a 1200 baud variant in their BBC Micro and Acorn Electron which the coding of '0 'to a full wave of the sine wave at 1200 Hz and the '1' reduced to two waves of the sinusoid at 2400 Hz. This extension looks just a start bit is '0 ', eight data bits and one stop bit '1' before; it results in a data rate of 120 bytes per second ( 1200 / ( 1 8 1)).

The extension requires a block length of 256 bytes including sequential numbering; between the blocks must be a time gap at 2400 Hz tone (carrier ). This allows for a read error rewinding to a block in front of the mis-read was.

Computer assisted by the Kansas City standards

Early micro - computer (some of them with S-100 bus):

  • Compukit UK101
  • Lucas Nascom 1, 2 (which is also a 1200 bit / s version supported )
  • MITS Altair 8800
  • MOS / CBM KIM -1
  • Motorola MEK 6800 D1 board
  • Ohio Scientific C1P/Superboard II
  • Processor Tech SOL -20 Terminal Computer
  • Processor Tech CUTER S-100 backplane bus
  • SWTPC 's 6800 - based computer
  • Eltec 6802 computer Eurocom 1

Home / Personal Computer:

  • ABC 80
  • Acorn Computers Ltd Acorn Atom ( 300 baud )
  • BBC Micro ( 300 and 1200 baud variants)
  • Acorn Electron (only 1200 baud )
  • Heathkit H8 (300 and 1200 baud )
  • Heathkit H89 (sold also as Zenith Z89 ) (300 and 1200 baud )
  • Alphatronic PC
  • Alphatronic PC16

Programmable Calculators:

  • Casio FX- 602P
  • FX- 702P
  • PB700 ( with Casio FA -11 interface)
Kansas City (Missouri) Interpreter (computing) Network packet Bit numbering Micro Instrumentation and Telemetry Systems KIM-1 Motorola 6800 Zenith Z-89 Commodore Datasette
463444
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