DP83266VF National Semiconductor, DP83266VF Datasheet - Page 9

• Manufacturer Part Number: DP83266VF
• Description: IC MEDIA ACSS CTRL INTF 160PQFP
• Manufacturer: National Semiconductor

Specifications of DP83266VF

• Applications: *
• Voltage - Supply: 4.75 V ~ 5.25 V
• Package / Case: 160-BFQFP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Other names: *DP83266VF

3 0 Architectural Description
Confirmation Messages (CNFs) are created by the MACSI
device to record the result of a Request operation
Pool Space Descriptors (PSPs) describe the location and
size of a region of memory space available for writing Input
Data Units
Request (transmit) and Indicate (receive) data structures
are summarized in Figure 3-3
3 3 2 Descriptor Queues and Lists
The MACSI device uses 10 Queues and two Lists which are
circular There are six Queues for Indicate operations and
four Queues and two Lists for Request operations Each of
the three Indicate Channels has a Data Queue containing
Pool Space Descriptors (PSPs) and a Status Queue con-
taining Input Data Unit Descriptors (IDUDs) Each Request
Channel has a Data Queue containing Request Descriptors
(REQs) a Status Queue containing Confirmation Messages
(CNFs) and a List containing Output Data Unit Descriptors
(ODUDs)
During Indicate and Request operations Descriptor Queues
and Lists are read and written by the MACSI device using
registers in the Pointer and Limit RAM Register files The
Pointer RAM Queue and List Pointer Registers point to a
location from which a Descriptor will be read (PSPs and
REQs) or written (IDUDs and CNFs) All of the Queues and
Lists are strictly unidirectional The MACSI consumes ob-
jects in those queues which are produced by the Host The
Host consumes objects in those queues which are pro-
duced by the MACSI
(Continued)
9
For each Queue Pointer Register there is a corresponding
Queue Limit Register in the Limit RAM Register file which
holds the Queue’s limit as an offset value in units of 1 De-
scriptor (8 bytes) The address in the Queue Pointer is incre-
mented before a Descriptor is read and after a Descriptor is
written then compared with the value in the corresponding
Queue Limit Register When a Queue Pointer Register be-
comes equal to the Queue Limit Register an attention is
generated informing the host that the Queue is empty
When a pointer value is incremented past the end of the
page it wraps to the beginning of the page
3 3 3 Storage Allocation
The maximum unit of contiguous storage allocation in exter-
nal memory is a Page All MACSI device addresses consist
of a 16-bit page number and a 12-bit offset
The MACSI device uses a page size of 1 kByte or 4 kBytes
for storage of Descriptor Queues and Lists (as selected by
the user) and a page size of 4 kBytes for storage of Data
Units A single page may contain multiple Data Units and
multiple-part Data Units may span multiple disjoint or con-
tiguous pages
3 4 SERVICE ENGINE
The Service Engine which manages the operation of the
MACSI contains seven basic blocks Indicate Machine Re-
quest Machine Status Space State Machine Pointer RAM
Limit RAM and Bus Interface Unit An internal block dia-
gram of the Service Engine is shown in Figure 3-4
3 4 1 Indicate Machine
The Indicate Block accepts Service Data Units (frames)
from the Ring Engine (MAC) in a byte stream format
(MA Indicate)