HP 30240A Installation And Service Manual page 37

LANIC MPU and Firmware
Local intelligent control is provided by a microprocessor (MPU) and firmware
on the LANIC card. An 8-bit microprocessor. type Z-80B. handles all the
LANIC-to-host communication and performs many link-level operations
independently of the host. The MPU also is responsible for performing an
on-board self test to detect and locate hardware faults. The firmware for the
MPU resides in both ROM and RAM. The ROM firmware has the self test.
MPU interrupt control. and bootstrap programs. The link-level operational
firmware is downloaded into LANIC RAM from system memory.
Local Communications Controller
The Local Communications Controller (LCC) is a high-performance LSI device
that performs most of the data link and physical link functions for the local
network architecture. The LCC performs high-speed serial operations. packet
address checking. network contention control. packet formatting, and CRC
(Cyclic Redundancy Check) generation/checking. The LCC is controlled by the
MPU through local memory.
Direct Memory Access
The LANIC can transfer data directly to and from system memory. Once the
host has given the LANIC the location of data buffers in system memory, data is
transferred without host intervention. This allows maximum system performance
by uploading the task of packet transmission and reception from the host.
allowing the host to spend more of its time on other processing.
Principles of Operation
3-3