Download iSBC 80/05 SINGLE BOARD COMPUTER HARDWARE

Preparation for Use
SBC 80/0S
Table 2-6. Multibus Signal Functions
SIGNAL
FUNCTIONAL DESCRIPTION
ADRO/-ADRF /
Address. These 16 address lines transmit the address of the memory location
or I/O port to be accessed. ADRF / is the most-significant bit.
BCLK/
Bus Clock. Used to synchronize bus control circuit on all master boards.
BCLK/ from the SBC 80/05 has a period of 101.72 nanoseconds
(9.8304 MHz frequency) with a 35-65 percent duty cycle.
BPRN/
Bus Priority In. Indicates to a particular master board that no higher priority
master board is requesting use of the bus. BPRN/ is synchronized with
BCLK/.
BPRO/
Bus Priority Out. In serial (daisy chain) priority resolution schemes, BPRO/
must be connected to the BPRN/ input of the master board with the
next lower bus priority.
BREQ/
Bus Request. Used with a parallel bus priority resolution scheme to indicate
that a particular master board requires use of the bus for one or more
data transfers. BREQ/ is synchronized with BCLK/.
BUSY/
Busy. Indicates that the bus is in use and prevents all other master boards
from gaining control of the bus. BUSY/is synchronized with BCLK/.
CCLK/
Constant Clock. Provides a clock signal of constant frequency (9.8304 MHz)
for use by system boards. CCLK/ from the SBC 80/05 coincides with
BCLK/ and has a period of 101.72 nanoseconds with a 35-65 percent
duty cycle.
DATO/-DAT7/
Data. These eight bidirectional data lines transmit and receive information
to and from the addressed memory location or I/O port. DAT7/ is the
most-significant bit.
INIT/
Initialization. Resets the entire system to a known internal state.
INTO/-INT7 /
Interrupt. These eight lines are used for system interrupt requests.
10RC/
1/0 Read Command. Indicates that the address of an I/O port is on the
system address lines and that the output of that port is to be read
(placed) onto the system data lines.
10WC/
I/O Write Command. Indicates that the address of an I/O port is on the
system address lines and that the contents on the system data lines
are to be accepted by the addressed port.
MRDC/
Memory Read Command. Indicates that the address of a memory location
is on the system address lines and that the contents of that location
are to be read (placed) onto the system data lines.
MWTC/
Memory Write Command. Indicates that the address of a memory location
is on the system address lines and that the contents on the system
data lines are to be written onto that location.
XACK/
Transfer A cknowledge. Indicates that the addressed memory location or I/O
port has completed the specified read or write operation. That is, data.
has been placed onto or accepted from the system data lines.
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