Transfer Count

A 1-WORD field containing the record transfer count. The sign bit of this WORD is set to request one of the following actions:
• Wait for the requested number of keystrokes to become available. The physical device driver blocks the requestor until all requested Character Data Records are available and are transferred to the caller.

• Do not wait for the requested number of keystrokes to become available. In this case, all characters currently available are transferred up to the requested transfer count.