Glossary- Y
A Data Communication Historical Series
By Bob Pollard

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YELLOW ALARM:

In T1, an alarm sent by the remote site to the local site when the second bit position is zero in every channel in a T1 frame. The yellow alarm is sent to the local site after a red alarm occurs at the remote site.

YMODEM:

A protocol that transfers larger data blocks than the XMODEM protocol. A communications protocol very similar to XMODEM designed to perform simple error checking between micro-computers. YMODEM is a half-duplex protocol, used on full-duplex circuits transmitting a 1 kilobyte (1,024) characters per block. After information is sent, the sender waits for a reply before transmitting the next message.

YMODEM-G:

References streaming protocols designed to optimize file transfer