Asynchronous Communications Adapter Block Diagram - IBM 5150 Hardware Reference Manual

• False Start Bit Detection.
• Complete Status Reporting Capabilities.
• Line Break Generation and Detection.
• Internal Diagnostic Capabilities.
Loopback Controls for Communications Link Fault
Isolation.
Break, Parity, Overrun, Framing Error Simulation.
• Full Prioritized Interrupt System Controls.
All communications protocol is a function of the system microcode
and must be loaded before the adapter is operational. All pacing ofthe
interface and control signal status must be handled by the system
software.
Asynchronous Communications Block Diagram
ADDRESS BUSS CHIP SELECT
ADDRESS
DECODE
DATA BUS
INTERRUPT
8250
ASYNCH RONOUS
COMMUNICATIONS
OSCILLATOR
ELEMENT
--"
1.8432 Mhz
EIA
EIA
RECEIVERS
DRIVERS
A
CURRENT LOOP
Y
~
A
L
J
L.
25 PIN
"D"SHELLCONNECTOR
Figure 22. ASYNCHRONOUS COMMUNICATIONS ADAPTER
BLOCK DIAGRAM
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