IEEE 488.2 Controller Chip
NAT9914
Pin compatible with TI TMS9914A
Software compatible with
NEC 碌PD7210 or TI TMS9914A
controller chips
Low power consumption
Meets all IEEE 488.2 requirements
Bus line monitoring
Preferred implementation of
requesting service
Will not send messages when there
are no Listeners
Performs all IEEE 488.1
interface functions
Programmable data transfer rate
(T1 delays of 350 ns, 500 ns,
1.1 碌s, and 2 碌s)
Automatic EOS and/or NL message
detection
Direct memory access (DMA)
Automatically processes IEEE 488
commands and reads
unde鏗乶ed commands
TTL-compatible CMOS device
Programmable clock rate
20 MHz maximum
Reduces driver overhead
Does not lose a data byte
if ATN is asserted while
transmitting data
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Description
The NAT9914 IEEE 488.2 controller chip can perform all the
interface functions de鏗乶ed by the IEEE Standard 488.1-1987, and
also meets the additional requirements and recommendations
of the IEEE Standard 488.2-1987. Connected between the
processor and the IEEE 488 bus, the NAT9914 provides high-
level management of the IEEE 488 bus, signi鏗乧antly increases
the throughput of driver software, and simplifies both the
hardware and software design. The NAT9914 performs
complete IEEE 488 Talker, Listener, and Controller functions. In
addition to its numerous improvements, the NAT9914 is also
completely pin compatible with the TI TMS 9914A and
software compatible with the NEC 碌PD7210 and TI TMS9914A
controller chips.
General
The NAT9914 manages the IEEE 488 bus. You program the
IEEE 488 bus by writing control words into the appropriate
registers. CPU-readable status registers supply operational
feedback. The NAT9914 mode determines the function of
these registers. On power up or reset, the NAT9914 registers
resemble those of the TMS9914A set, with additional registers that
supply extra functionality and IEEE 488.2 compatibility. In this
mode, the NAT9914 is completely pin compatible with
the TI TMS9914A. If you enable the 7210 mode, the registers
resemble those of the NEC 碌PD7210 set, with additional registers
that supply extra functionality and IEEE 488.2 compatibility. This
mode is not pin compatible with the NEC碌PD7210. Figure 4
shows the key components of the NAT9914.
IEEE 488.2 Overview
The IEEE 488.2 standard removes the ambiguities of IEEE 488.1
by standardizing the way instruments and controllers operate. It
defines data formats, status reporting, error handling, and
common configuration commands to which all IEEE 488.2
instruments must respond in a precise manner. It also de鏗乶es a
set of controller requirements. With IEEE 488.2, you gain the
bene鏗乼s of reduced development time and cost because systems
are more compatible and reliable. The NAT9914 brings the full
power of IEEE 488.2 to the design engineer along with
numerous other design and performance benefits, while
retaining the 40-pin and 44-pin hardware con鏗乬urations of the
TI TMS 9914A.
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