TI380C30A Datasheet, PDF (12/81 Pages) Texas Instruments – INTEGRATED TOKEN-RING COMMPROCESSOR AND PHYSICAL-LAYER INTERFACE

TI380C30A
INTEGRATED TOKEN-RING COMMPROCESSOR
AND PHYSICAL-LAYER INTERFACE
SPWS034 – MARCH 1998
Terminal Functions (Continued)
TERMINAL
NAME
NO.
I/O/E†
DESCRIPTION
SCS
System-chip select. SCS activates the system interface of the TI380C30A for a DIO read or write.
66
I
H = Not selected (see Note 1)
L = Selected
SDBEN
System data-bus enable. SDBEN signals to the external data buffers to begin driving data. SDBEN is
activated during both DIO and DMA.
95
O
H = Keep external data buffers in the high-impedance state
L = Cause external data buffers to begin driving data
SDDIR
System data direction. SDDIR provides to the external data buffers a signal indicating the direction in
which the data is moving. During DIO writes and DMA reads, SDDIR is low (data direction is into the
TI380C30A). During DIO reads and DMA writes, SDDIR is high (data direction is out from the
TI380C30A). When the system interface is not involved in a DIO or DMA operation, SDDIR is high by
75
O
default.
SDDIR
H
L
Data
Direction
Output
Input
DIO
Read
Write
DMA
Write
Read
SHLDA/SBGR 74
Intel
mode
I
SHLDA is used for system-hold acknowledge. SHLDA indicates that the system DMA-hold
request has been acknowledged. SHLDA is internally synchronized to SBCLK (see
Note 1).
H = Hold request acknowledged
L = Hold request not acknowledged
Motorola
mode
SBGR is used for system bus grant. SBGR is an active-low bus grant, as defined in the
standard 68xxx interface, and is internally synchronized to SBCLK (see Note 1).
H = System bus not granted
L = System bus granted
SHRQ/SBRQ ⁹³
SHRQ is used for system-hold request. SHRQ is used to request control of the system bus
Intel
in preparation for a DMA transfer. SHRQ is internally synchronized to SBCLK.
mode
H = System bus requested
L = System bus not requested
O
SBRQ is used for system-bus request. SBRQ is used to request control of the system bus
Motorola ^{in preparation for a DMA transfer. SBRQ is internally synchronized to SBCLK.}
mode
H = System bus not requested
L = System bus requested
SIACK
System-interrupt acknowledge. SIACK is for the host processor to acknowledge the interrupt request
from the TI380C30A.
61
I
H = System interrupt not acknowledged (see Note 1)
L = System interrupt acknowledged: The TI380C30A places its interrupt vector onto the system bus.
System-Intel/Motorola mode select. The value on SI/M specifies the system-interface mode.
SI/M
72
I
H = Intel-compatible-interface mode selected. Intel-interface mode can be 8 bit or 16 bit (see S8/SHALT
description and Note 1).
L = Motorola-compatible-interface mode selected. Motorola-interface mode is always 16 bits.
SINTR/SIRQ 73
SINTR is used for system-interrupt request. TI380C30A activates SINTR to signal an
Intel
interrupt request to the host processor.
mode
H = Interrupt requested by TI380C30A
L = No interrupt request
O
SIRQ is used for system-interrupt request. TI380C30A activates SIRQ to signal an interrupt
Motorola ^{request to the host processor.}
mode
H = No interrupt request
L = Interrupt requested by TI380C30A
† _{I = input, O = output, E = provides external-component connection to the internal circuitry for tuning}
NOTE 1. Terminal has an internal pullup device to maintain a high-voltage level when left unconnected (no etch).
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