RS-232 converter to go in the Logic Lab
<UL>
<LI><b>loop-rs232o</b> is an older version of the  current loop to RS-232 converter (CTS 
flow control only).</LI>
<LI><b>loop-rs232</b> is a slightly newer version of the current loop to RS-232 converter, 
with CTS or DTR flow control.</LI>
<LI><b>sel-driver.sch</b> is a schematic of the selector magnet driver card in the TTY.</LI>