Memory Buffer of GPIB Interfaces

Updated Jan 18, 2023

Reported In


  • PCI-8232
  • PXI-8232

Issue Details

Is the onboard memory of a GPIB device volatile? How do I clear it? How much and what kind of memory are on your GPIB solutions?


GPIB Device
Assembly number(s)RAMFlashEEPROMGAL Programmable LogicGPIB Chip
AT-GPIB/TNT (PnP)183663x-01--256x8-TNT4882C
GPIB-120A181555x-01No RAM, only flip flops---None
GPIB-130181460-01512x8 bit FIFO-36 Kbytes-Logic Array
GPIB-140A186104x-011Kbyte SRAM + 512x9 bit FIFO---Implemented in FPGA
GPIB-232CV-A181935K-01DRAM - 256Kx4---NAT4882
GPIB-485CT-A777146-01256x4 Kbytes-32x8 Kbytes-NAT4882
GPIB-ENET/100186852x-012 x 64 Mbytes SDRAM2 Mbytes-16V8TNT4882C
GPIB-ENET/1000196541x-012 x 512 Mbit
256 Mbit--TNT5004
GPIB-RS232779732-01512 Mbytes32 Mbytes--TNT5004
GPIB-USB-B188417x-0132 Kbytes-16 bytes-TNT5004
GPIB-USB-HS187965x-0148 Kbytes-32 Kbytes-TNT5004
GPIB-VME187751x-01--8 Kbytes16V8TNT4882C
NI Express Card-GPIB192072x-0132Kx8 SRAM-32Kx8-TNT5004
PCI-GPIB183617x-01--8 Kbytes-TNT4882C
PCI-GPIB+183617x-024608 bytes-8 Kbytes-TNT4882C
PCI-GPIB188513x-01--256 bytes-TNT5004
PCIe-GPIB190243x-01368 bytes8 Kbytes128 bytes-TNT5004
PCI-8232189761x-01--128 bytes-TNT5004
PXI-8232189761x-01--2 x 1Kbyte-TNT5004
PCMCIA-GPIB+182780x-012K x 18 FIFO---TNT4882C
PMC-GPIB184021x-01--128 bytes-TNT5004
The assembly number should be printed on the card itself labelled either "ASSY" or "PART NO".

In general, there are three types of memories used on National Instruments GPIB products:
  1. Chip—All GPIB hardware solutions include ASICs (chips) that perform the GPIB communication. Common ASICs on National Instruments boards include the TNT4882C, TNT5004, NAT7210, and NAT9914. All these chips have buffers to store bytes received or sent over GPIB as well as registers for communication to the computer's bus. These buffers are internal to the chips themselves. All of these memories are cleared when power is turned off. 
  2. RAM—External RAM is used in some devices. For example, the GPIB-140A, GPIB-ENET/100, and GPIB-USB-HS all use external RAM to store user data while the interface is running. This memory is usually a separate chip on the circuit card assembly. This memory is cleared when the power is turned off. 
  3. Non-volatile memory—Non-volatile memory is present in either flash, EEPROM, or GAL Programmable Logic. This is used for firmware, configuration, ethernet MAC addresses, and serial numbers. This memory is not lost when it loses power. However, GPIB user data cannot be written to this memory during standard operation.
The National Instruments GPIB solutions listed above lose all user data when power is removed. The only exception is that network based units (such as GPIB-ENET/100 and GPIB-ENET/1000) will retain their IP address even after they are powered off. See the related link for details on the GPIB-ENET.