Set Mode; Expansion Feature Card; Addressing; Control Strobe - IBM 5100 Maintenance Information Manual

(
(
(
(
Set Mode
I n set mode, either the modem cable or the terminal cable
can be used to connect the I/O device to the 5100.
When the modem cable is used, the sequence and function
of the lines are the same as they are in modem mode.
(See Modem Mode.) However, the 5100 turns on '+SIO
request to send' (clear to send at the I/O device) without
checking the request to send line ('+SIO clear to send' at
the expansion feature card) from the I/O device. The
'+SIO request to send' line remains on during transmit and
receive operations.
When the terminal cable is used, the sequence and function
of the lines are the same as they are in terminal mode.
(See Terminal Mode.) However, the 5100 turns on '+SIO
request to send' (request to send at the I/O device) and does
not check the clear to send line ('+SIO clear to send' line
at the expansion feature card) before sending data to the
I/O device. The '+SIO request to send' line remains on
during transmit and receive operations.
Note: The signal ground line provides a common ground
for all circuits. The protective ground line is connected
to the frame of the 5100.
EXPANSION FEATURE CARD
The expansion feature card is the interface between the
base I/O card and the data set or serial I/O device. The
card:
• Stores control information and transmit data that is
sent by the communications or serial I/O microprogram
• Stores status information and received data that is read
by the communications or serial I/O microprogram
• Provides interrupts to the communications or serial
I/O microprogram at a selectable rate for receive data
sampling and transmit timing
• Contains drivers and receivers to convert the data set
and serial I/O device EIA voltage levels to 5100 voltage
levels
• Checks the device address and bus out for correct parity
when the expansion feature card is addressed
• Monitors the 'rcvd data' line during communications
receive operations for a long space condition, and sig·
nals the processor via an interrupt when a long space
occurs
• Switches between the communications and serial I/O
connector
Refer to the expansion feature card logic diagram in the
IBM 5100 Maintenance Information Manual while reading
the following description of the expansion feature card
operation.
Addressing
The expansion feature card is addressed by the '+device adr
X3' and '+device adr Y3' (OAF) or '+device adr YO' and
'+device adr X2' (DAB) lines from the base I/O card on the
device address bus.
OAF (device address F), '·control strobe', and '·bus out 0'
reset the card logic.
DAB (device address B) addresses the adapter during func·
tions other than reset.
Control Strobe
The '·control strobe' line is made active by the communi·
cations I/O microprogram or the serial I/O input/output'
microprogram to gate control information to the card.
This control information is sent to the card on bus out and
controls the card when the lines are active as follows:
'·bus out 0'
The timer interrupt latch is allowed to be set so the
card can generate a program level 1 interrupt.
'·bus out 2'
The data rate clock starts when a start bit is received.
If '·bus out 2' is inactive, the clock is allowed to run
conti nuously.
'·bus out 3'
The timer interrupt latch is reset.
Theory Of Operation 2-15