| The DRX Interface is a general
purpose digital plug-in board for IBM PC/XT or compatible computers
with I/O connectors pin compatible with DEC's DRV 11 type interfaces.
The board provides 16 bit data I/O, two control lines (CSR 0 and CSR
1), two status bits (Request A and Request B), two interrupt and
interrupt enable controls. The purpose of the DRX-Interface is to
replace older PDP-11 series computers with more advanced IBM PC's or
compatibles without any additional hardware. The DRX board may be used
for fast data transfer between PDP-11 and IBM PC computers. Since the
IBM PC/XT has only an eight bit data bus, to transfer a 16 bit word in
or out, it takes two instructions to complete the 16 bit data transfer.
Two additional status bits monitor proper I/O connections (reversed
connector or missing connection).