GPIB chips
While it is possible to drive GPIB pins directly from a microcontroller's GPIO ports, the electrical and protocol characteristics are challenging enough that most vendors implement GPIB through one of a set of available single-chip solutions.
A GPIB device can be a talker (sends information to the bus), listener (receives information from the bus), or controller, which manage the bus and connected devices. GPIB chips embedded in host-side GPIB interfaces (GPIB-USB, PCI-GPIB and so on) are generally all three: talker, listener, controller (TLC).
A full GPIB chipset traditionally consists of a GPIB interface chip (such as NEC µPD7210, TI 9914A, or NI TNT4882), an 8-pin control pin transceiver chip (TI SN75161B or SN75162B), and an 8-pin data transceiver chip (TI SN75160B or some form of 74245).
Interface chips
NEC µPD7210
Texas Instruments 9914A
National Instruments NAT9914A
National Instruments NAT4882
National Instruments TNT4882
The TNT4882 is a Talker/Listener ASIC which is software-compatible with the NAT4882.
National Instruments TNT5002
Talker/Listener ASIC
National Instruments TNT5004
Talker/Listener/Controller ASIC