Introduction - AT&T 3B2 Off-Line Diagnostic Manual

Intro~uction
This chapter contains the diagnostic phases and tests for the 3B2 computer Intelligent Serial
Controller (ISC) card. Diagnostics test the following components on the ISC card:
• INTEL 80186 Central Processing Unit (CPU)
• Peripheral Control and Status Register (PCSR)
• Random Access Memory (RAM)
• Read Only Memory (ROM)
• Universal Synchronous/Asynchronous Receiver/Transmitter (USART).
An important external component of the ISC card is the 3B2 computer Input/Output (I/O) bus.
The ISC card uses the 3B2 computer I/O bus to communicate with the UNIX operating system.
If your 3B2 computer is equipped with an ISC card, the Equipped Device Table (EDT) should list it.
You can use the diagnostic monitor command show (DGMON> s) to display the EDT. If the ISC card
is not listed in the EDT and a VOID or NULL is listed, the following hardware devices on the ISC card
may be faulty:
• INTEL 80186 CPU
• ISC ROM
• ISC ID/Vector register
• ISC Address/Data bus
• ISC interface to the 3B2 computer I/O bus.
Eighteen diagnostic phases run tests on all major ISC card components. Phase 1 is a normal
diagnostic phase. Phases 2 through 13 are demand diagnostic phases, and Phases 14 through 18 are
interactive diagnostic phases.
Phases 14 through 18 require special cabling. Phase 14 is not used for diagnostics on the ISC card.
Phase 14 is a debug monitor used by software developers; it also requires a clock source. The cabling
information for Phases 14 through 18 is given in their sections of this chapter.
Use the Table of Contents to locate the desired description for each ISC card phase and its
associated tests. The phase and test descriptions are organized in numerical order.
INTELLIGENT SERIAL CONTROLLER DIAGNOSTICS 6-1