EXTENDED CAPABILITIES PARALLEL PORT
ECP provides a number of advantages, some of
reverse: Peripheral to Host communication
Pword: A port word; equal in size to the width of
the ISA interface. For this
which are listed below. The individual features are
explained in greater detail in the remainder of this
section.
implementation, PWord is always 8 bits.
1
0
A high level.
A low level.
•
•
•
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
These terms may be considered synonymous:
•
•
•
•
•
•
•
•
•
PeriphClk, nAck
HostAck, nAutoFd
PeriphAck, Busy
nPeriphRequest, nFault
nReverseRequest, nInit
nAckReverse, PError
Xflag, Select
ECPMode, nSelectln
HostClk, nStrobe
•
•
•
•
•
Vocabulary
The following terms are used in this document:
Reference Document:
Capabilities Port Protocol and ISA Interface
Standard, Rev 1.14, July 14, 1993. This
document is available from Microsoft.
IEEE 1284 Extended
assert: When a signal asserts it transitions to a
"true" state, when a signal deasserts it
transitions to a "false" state.
forward: Host to Peripheral communication.
96
SMSC [ SMSC CORPORATION ]
