Text preview for : DOS-73_Technical_Reference.pdf part of AT&T DOS-73 Technical Reference AT&T 3b1 hardware DOS-73_Technical_Reference.pdf
Back to : DOS-73_Technical_Referenc | Home
PREFACE
INTENDED AUDIENCE
The DOS-73 Technical Reference is written for technicians doing component-level
trou bleshooting of the DOS-73 Coprocessor board.
ORGANIZATION OF THIS MANUAL
System Features and Functions
Briefly describes the physical features and functional capabilities of the
DOS-73 Coprocessor board.
DOS-73: Theory Of Operation
Describes the DOS-73 hardware and the functions performed by it.
Diagnostics
Describes DOS-73 Coprocessor diagnostic procedures.
1.
CONTENTS
1: System Features and Functions
General Description................................................................................................................................. 1-2
DOS-7 3 Archi tecture................................................................................................................................ 1-2
DOS-73 Block Diagram........................................................................................................................... 1-3
2: DOS-73: Theory Of Operation
cPu.................................................................................................................................................................. 2-2
Memory Organization.............................................................................................................................. 2-3
COM2: Emula tion...................................................................................................................................... 2-4
Timer Emulation........................................................................................................................................ 2-5
Interrupt System......................................................................................................................................... 2-5
I/O Intercept System................................................................................................................................ 2-6
Video Intercept System........................................................................................................................... 2-7
Math Coprocessor Emulation............................................................................................................... 2-7
UNIX Interface.......................................................................................................................................... 2-8
Software Driver Specifications.......................................................................................................... 2-10
DOS-73 Hard ware....................................................................................................................... 2-10
User Level Interface................................................................................................................. 2-13
3: Diagnostics
Testing The COM2: Port......................................................................................................................... 3-2
Number Of Test Passes........................................................................................................................... 3-2
Test Descriptions....................................................................................................................................... 3-3
In Case Of Trouble................................................................................................................................... 3-6
11.
1: SYSTEM FEATURES AND FUNCTIONS
General Description................................................................................................................................. 1-2
DOS-73 Architecture................................................................................................................................ 1-2
DOS-73 Block Diagram........................................................................................................................... 1-3
1-1
SYSTEM FEATURES AND FUNCTIONS
GENERAL DESCRIPTION
The DOS-73 coprocessor is a peripheral product designed to bring MS-DOS capabilities to
the AT&T UNIX PC. The DOS-73 hardware is essentially a PC "on a board," with several
enhancements. The hardware enhancements include: Hercules monochrome graphics emula-
tion (first page only), PC COM2: port emulation, Microsoft Mouse emulation using the
mouse, and increased performance due to a full 16 bit bus and increased clock speed. This
document describes the DOS-73 hardware and outlines the DOS-73/7300/UNIX interface
standards as ALLOY has defined them.
DOS-73 Architecture
The DOS-73 hardware was designed to parallel the PC architecture. The hardware also in-
cludes enhancements which allow it to be integrated into a multi-processor environment,
and improvements. The system includes the following:
8086 CPU
512K Bytes Dynamic RAM
Memory Timing & Control Circuitry
INS8250 Asynchronous Communications Element
Interface Circuitry to the 7300 bus
18259 Programmable Interrupt Controller
18253 Programmable Timer
V ideo Data Handling Circuitry
I/O Intercept Circuitry
8087 Numeric Coprocessor Hooks
A block diagram of the board is found on the following page.
1-2
System Features and Functions
DOS-73 BLOCK DIAGRAM
I COM2: 1
~ ~~;!3"r Refresh
I~~~IM I II r
I ~
CM