25.03.2015 Views

IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

• False Start Bit Detection.<br />

• Complete Status Reporting Capabilities.<br />

• Line Break Generation and Detection.<br />

• Internal Diagnostic Capabilities.<br />

Loopback Controls for Communications Link Fault <br />

Isolation. <br />

Break, Parity, Overrun, Framing Error Simulation. <br />

• Full Prioritized Interrupt System Controls.<br />

All communications protocol is a function of the system microcode<br />

and must be loaded before the adapter is operational. All pacing ofthe<br />

interface and control signal status must be handled by the system<br />

software.<br />

Asynchronous Communications Block Diagram<br />

ADDRESS BUSS<br />

ADDRESS <br />

DECODE <br />

CHIP SELECT<br />

DATA BUS<br />

INTERRUPT<br />

OSCILLATOR<br />

1.8432 Mhz <br />

--" <br />

8250<br />

ASYNCH RONOUS<br />

COMMUNICATIONS<br />

ELEMENT<br />

EIA<br />

RECEIVERS<br />

EIA<br />

DRIVERS<br />

A<br />

CURRENT LOOP<br />

Y ~<br />

J<br />

A<br />

L<br />

L.<br />

25 PIN<br />

"D"SHELLCONNECTOR<br />

Figure 22. ASYNCHRONOUS COMMUNICATIONS ADAPTER <br />

BLOCK DIAGRAM <br />

2-124

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!