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8-6
ISDN and 16-bit Audio
DBRI Overview
Time Slots
Each of the DBRl's three serial interfaces (CHI, NT and TE) can have time
slots defined for them. A time-slot descriptor (TSD) must be assigned to
one end of the data pipe in order for data to enter or leave that end of the
data pipe via a serial interface
Each basic rate interface (BRI) is viewed as a 19-bit long bit string
consisting of the B1 and B2 channels (8 bits each), followed by an S or Q
channel bit, and then 2 bits of D channel data. A time slot on a basic rate
interface can be between 1 bit and 16 bits long. B1 and B2 can be
concatenated and viewed as a single 16-bit time slot. For the BRI B
channels, different time-slot descriptors can be used to overlap transmit and
receive time slots. Multiple time slots from the same interface can connect
to the same data pipe in the same direction (noncontiguous mode). The time
slots do not have to be contiguous.
A time slot on the CHI can be up to 255 bits long.
There are a number of restrictions on the use of time slots:
•
Time slots from different interfaces cannot be connected to the same
data pipe in the same direction.
•
For the CHI, the time-slot descriptors must not define overlapping time
slots.
•
CHI time slots that are greater than 32 bits long must connect to long
data pipes.
•
No CHI time slot can start within 0.975
µ
s after the start of the
previous time slot.
The DBRI does not enforce these restrictions, but peculiar actions result
from their violation.
Linked Lists
The time-slot descriptors are assembled into circular linked lists, one in
each direction for the CHI and the two BRI interfaces. These linked lists
must be maintained when using the Define Time Slot (DTS) command.
When using any serial interface, the first time slot defined is assigned to the
anchor pipe. That is: the TE receive time-slot list starts with the D channel
in pipe 0; the TE transmit time-slot list starts with the D channel in pipe 1;
the NT receive time-slot list starts with the D channel in pipe 3; and the NT
transmit time-slot list starts with the D channel in pipe 2.
Both CHI time-slot linked lists (transmit and receive) start in pipe 16 (CHI
anchor pipe). When initiating pipe 16, the CHI anchor mode must be used
in the time-slot descriptor (TSD) field of the DTS command.
S3GX_TRMBook Page 6 Friday, September 19, 1997 11:39 am
Содержание SPARCbook 3 series
Страница 1: ...Series Technical Reference Manual 980327 02 3 S3GX_TRMBook Page i Friday September 19 1997 11 39 am...
Страница 8: ...viii S3GX_TRMBook Page viii Friday September 19 1997 11 39 am...
Страница 28: ...1 16 Architecture Overview Microcontroller Subsystem S3GX_TRMBook Page 16 Friday September 19 1997 11 39 am...
Страница 44: ...2 16 The SPARC CPU SBus Controller S3GX_TRMBook Page 16 Friday September 19 1997 11 39 am...
Страница 76: ...5 8 SCSI Controller DMA Support S3GX_TRMBook Page 8 Friday September 19 1997 11 39 am...
Страница 82: ...6 6 Ethernet Interface DMA Support for Network Operations S3GX_TRMBook Page 6 Friday September 19 1997 11 39 am...
Страница 96: ...7 14 PCMCIA Interface Microcontroller Registers S3GX_TRMBook Page 14 Friday September 19 1997 11 39 am...
Страница 146: ...9 28 MODEM Class 2 Fax Command Set S3GX_TRMBook Page 28 Friday September 19 1997 11 39 am...
Страница 180: ...11 30 Display Interface RAMDAC S3GX_TRMBook Page 30 Friday September 19 1997 11 39 am...
Страница 210: ...B 10 Connector Information Removable Hard Drive SCSI Connector S3GX_TRMBook Page 10 Friday September 19 1997 11 39 am...
Страница 216: ...Index vi S3GX_TRMBook Page vi Friday September 19 1997 11 39 am...