
It's made by (SURPRISE) National Instruments:
6504 Bridge Point Parkway
Austin, TX 78730-5039
(800) 433-3488
anonymouse ftp at: ftp.natinst.com

Their 1991 catalog lists the NB-8G as follows:

fetch and deposit DMA controller (8 channels)
IEEE-488 interface with data rates up to 850 kB/sec, with DMA and
programmed I/O
   transfers
8 16-bit counter timer channels
RTSI bus (that's the connector on the top of the board - it links it with
   other National Instrument boards
List price of $1295