Z80382 Datasheet, PDF (43/77 Pages) Zilog, Inc. – HIGH-PERFORMANCE DATA COMMUNICATIONS PROCESSORS

Zilog
Key Detect
ISA - PnP
Read/Write Logic
Address Port
Write Data Port
Read Data Port
Z80382/Z8L382
High-Performance Data Communications Processors
Internal Address/Data/Control Bus
Isolation,
Identification
and
Configuration
Controller
PnP Registers
Control
Configuration
I/O Address
Decoder
Interrupt
Request
Router
DMA
Req/Ack
Router
1
Mimic
I/O Mailbox
Z382
Interrupt
Request
Z80382
DMA
Req/Ack
Host ISA Address/Data/Control Bus
Figure 26. Plug and Play Interface
ISA Ports
The PnP interface implements three 8-bit ports on the ISA
bus. The ÓAddressÓ port is a write-only port at the fixed ad-
dress 0279H. The ÒWrite DataÓ port is a write-only port at
the fixed address 0A79H. The ÒRead DataÓ port is a read-
only port at a programmable address among 0203H,
0207H, 020BH, ..., 03FFH.
The Host may write to the Address port for three reasons:
1. As part of sending an ÒInitiation keyÓ to all the PnP
cards in the system.
2. To select a register on one or all PnP cards as the
destination of a subsequent write to the Write Data
port.
3. To select a register on one card, or the ÒIsolationÓ
facility on multiple cards, as the source of data in a
subsequent read from the Read Data port.
Basic Operation
The space that the Host can access by writing to the Ad-
dress port, and then writing to the Write Data port or read-
ing from the Read Data port, is in large part also accessible
to the 380C processor. Its 256 locations are sparsely pop-
ulated with hardware registers.
After reset, and on command from host software, including
in normal operation, the PnP interface is said to be in ÒWait
for KeyÓ state. In this state, none of the PnP locations are
accessible to the Host on the ISA bus. Before accessing
any of these locations, the Host must first do a specified
sequence of 34 write operations, called an Initiation key, to
the Address port before it can access any of the registers
of the PnP interface. The Initiation key is detected by the
PnP interface hardware.
DS97Z382000
PRELIMINARY
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