[GreenKeys] USB-teletype adapters (update)

[teletypeparts at comcast.net]

The 33 has the following on its Send side: 

1 start bit, always a space. 
7 data bits. 
8th bit is the parity bit. This is determined by the keyboard strapping or style of keyboard. ALT kybds were 8th (or parity) bit. A mark or a space all the time. Determined by slide on contacts on kybd. The 8th bit on these was almost always a mark. 
ESC kybds could be 8th bit either mark or space all the time but were generally strapped for Even parity. All characters were either 2, 4,6, or 8 mark bits. 
2 stop bits. 

The keyboard, tape reader and answerback are all wired in parallel to the distributor. The tape reader just reads what the tape has punched in it. The only device that can generate the parity bit is the keyboard. 

Look at the pic of the 33 printer distributor. 

On the Receive side, the printer only needs 1 start bit (a space) 7 data bits, and 1 stop bit (if its in good condition) otherwise 2 stop bits are needed. The 8th bit will punch in the tape, but is not needed by the printer to print correctly. 

Hope this helps. 

Wayne 
KB1FDW 

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