53
3 Interface Devices and Mass-Storage Drives
HP Ethernet 10/100 BaseT Network Board
Remote Power-On (RPO)
There is a cable from the Remote Start connector, on the network board, to
the External Start connector, on the system board. This is used by the
Remote Power-On feature (RPO) that is described on page 71. This cable
must be routed through the hole in the chassis. Not doing so, and allowing
the cable to be routed with the flexible disk drive and IDE cables, will raise
the risk of radio frequency interference (RFI) cross-talk.
The board is supplied with power, even whilst the rest of the computer is
turned off, via a line called VStandby on the External Start Connector. This
connector also carries the control lines which the network board uses to
turn on the main power supply, and to send or receive other control and
status information.
When shutdown into its RPO state, the 10 BaseT side of the board draws 30
mA, well within the 50 mA capability of the special RPO power supply. (The
100 BaseT side of the board would draw more than 50 mA if connected, and
hence does not support RPO).
Look-Ahead Packet
Processing (LAPP)
Standard drivers wait until a complete frame has been received before
processing it, and passing it to the application buffer. They then wait for the
controller buffer to be empty before starting to receive the next frame.
If there are many small frames, and a large amount of Windows application
switching, the network utilization rate can fall below 50%. The PC-Net
controller utilization of the system bus is about 4%. The remaining 96% can
be used by suitable LAPP drivers to start inter-frame data transfers to the
application stack buffer. By reducing the latency between frame reception,
the network utilization and throughput is increased.
Drivers
The board can be configured completely by software (no switches or
jumpers need changing). Drivers for the network board are supplied with
the computer. At the time of release, these bear the version number P.01.05.
