TNT4882
Single-Chip IEEE 488.2 Talker/Listener ASIC
National Instruments
Phone: (512) 794-0100 Fax: (512) 683-9300 info@natinst.com www.natinst.com
2
ISA
Interface
Logic
IEEE 488 Monitor
Interrupt Control
Configuration
and
Status Registers
Timer
Read/
Write
Control
Byte
Counter
IEEE 488
Transceivers
IEEE 488
Interface
Functions
HS488
Interface
Functions
FIFOs
I
GPIB
Turbo488 Circuitry
Read/
Write
Control
ISA
Interface
Logic
FIFOs
NAT4882
Interface
Circuitry
Byte
Counter
IEEE 488 Monitor
Read/
Write
Control
Timer
GPIB
Data
Registers
IEEE 488
Interface
Functions
Interrupt Control
Interrupt Control
NAT4882 Circuitry
Transfer
State
Machine
Configuration
and
Status Registers
Configuration
and
Status Registers
IEEE 488
Transceivers
L
Figure 1. TNT4882 One-Chip Mode
Figure 2. TNT4882 Two-Chip Mode
The register map of the NAT4882 portion of the TNT4882
changes to emulate either the 7210 or the 9914, but the
Turbo488 registers are identical in both chip emulation modes.
You cannot use one-chip mode with the 9914 emulation mode.
Because the Turbo488 was designed to interface to the 7210
and not the 9914, the software can rearrange the register map
of the 9914 mode NAT4882 registers so that the 9914 mode
Command/Data Out Register and Data In Register and the
Auxiliary Command Register appear at the same addresses as the
corresponding 7210 mode registers. The Turbo488 can then
perform DMA transfers with the NAT4882 in 9914 mode.
The TNT4882 has two different pin configurations – Generic
(see Figure 3) and ISA (see Figure 4). The TNT4882 determines
which configuration to use by the location of the power (VDD)
and ground pins. The Generic pin configuration provides a
simple interface to any CPU. Using the ISA pin configuration, you
can connect the TNT4882 directly to an ISA (IBM PC AT) bus
without any external glue logic or data transceivers. You can also
use the ISA pin configuration TNT4882 with an 8-bit (PC/XT) bus.
You may want to use the ISA version for interfaces other than an
ISA bus to take advantage of the built-in 5-bit address decoder
You can use two-chip mode, one-chip mode, 7210 mode, and
9914 mode identically with either pin configuration.
TNT4882 Block Diagrams