Pword: A port word; equal in size to the width
of the ISA interface. For this
implementation, PWord is always 8
bits.
EXTENDED CAPABILITIES PARALLEL PORT
ECP provides a number of advantages, some of
which are listed below. The individual features
are explained in greater detail in the remainder
of this section.
1
0
A high level.
A low level.
These terms may be considered synonymous:
·
·
·
High performance half-duplex forward and
reverse channel
Interlocked handshake, for fast reliable
transfer
Optional single byte RLE compression for
improved throughput (64:1)
Channel addressing for low-cost peripherals
Maintains link and data layer separation
Permits the use of active output drivers
Permits the use of adaptive signal timing
Peer-to-peer capability
·
·
·
·
·
·
·
·
·
·
PeriphClk, nAck
HostAck, nAutoFd
PeriphAck, Busy
nPeriphRequest, nFault
nReverseRequest, nInit
nAckReverse, PError
Xflag, Select
ECPMode, nSelectln
HostClk, nStrobe
·
·
·
·
·
Vocabulary
Reference Document:
The following terms are used in this document:
IEEE 1284 Extended Capabilities Port Protocol
and ISA Interface Standard, Rev 1.14, July 14,
assert: When a signal asserts it transitions to a
"true" state, when a signal deasserts it
transitions to a "false" state.
1993.
Microsoft.
This document is available from
forward: Host to Peripheral communication.
reverse: Peripheral to Host communication
The bit map of the Extended Parallel Port
registers is listed in the table on the following
page.
95
SMSC [ SMSC CORPORATION ]
