IBM Personal System/2 65 SX User Manual

The
Card-Selected
Feedback
register
is
a
read-only
register
at
address
hex
0091.
It
allows
programs
to
monitor
-CD
SFDBK
and
determine
if
the
video
subsystem,
system-board
I/O,
or
an
adapter
is
addressed
and
functioning.
Bit Function
7-1 Reserved
0
Card-Selected
Feedback
Figure
2-2.
Card-Selected
Feedback
Register
(Hex
0091)
Bilis 7-1 Reserved.
BitO
This
bit
is
set
to
1
whenever
-CD
SFDBK
was
active
ona
previous
cycle
or
whenever
the
system-board
I/O
functions
(diskette
drive,
serial,
or
parallel
interfaces)
are
accessed
by
an
I/O
cycle.
Reading
this
register
resets
the
bit
to
0.
System-Board
Setup
The
integrated
I/O
functions
on
the
system
board
use
POS
information
during
setup.
POS
treats
the
diskette-drive
controller,
serial
port,
and
parallel
port
as
a
single
device.
The
video
subsystem
also
is
an
integrated
part
of
the
system
board,
but
POS
treats
it
as
a
separate
device.
The
System-Board
Enable/Setup
register
is
used
to
place
the
system
board
or
the
video
subsystem
in
the
setup
mode.
2-6
Model
65
POS
—
October
1990

IBM Personal System/2 65 SX Specifications

General

Manufacturer	IBM
Model	Personal System/2 65 SX
Category	Desktop
CPU	Intel 80386SX
CPU Speed	16 MHz
Floppy Drive	3.5" 1.44 MB
Graphics	VGA
Operating System	PC DOS
Ports	Serial, Parallel, Keyboard, Mouse
Expansion Slots	Micro Channel Architecture (MCA) slots
Storage	40 MB hard drive (optional)

Summary

Special Notices

Section 1. System Overview

System-Board Features

Lists system-board devices and features for the Model 65 SX.

System-Board I/O Address Map

Shows the address map for system-board I/O functions.

Specifications

Details performance and physical specifications of the system.

Power Supply

Explains the power supply requirements and output voltages.

Section 2. Programmable Option Select

System-Board POS Address Map

Organizes the I/O address space used by system-board POS.

System-Board Setup

Explains POS information used by the system board for setup.

System-Board Enable/Setup Register (Hex 0094)

Controls system-board I/O functions and video subsystem setup.

System-Board POS Registers

Details POS registers for memory and configuration.

Adapter Setup

Selects the channel connector for configuration.

Section 3. System Board

Microprocessor and Math Coprocessor

Describes the 80386SX microprocessor and 80387SX math coprocessor.

Micro Channel Implementation

Details the Micro Channel architecture implementation.

Central Arbiter

Manages bus access and prioritization for intelligent subsystems.

Diskette-Drive Controller

Information on the Type 1 diskette-drive controller.

Memory

Overview of ROM, RAM, and RT/CMOS RAM types.

RT/CMOS RAM

Details the real-time clock and CMOS RAM chip.

Real-Time-Clock Bytes

Defines bit definitions and addresses for real-time clock bytes.

Status Registers

Details Status Registers A, B, C, and D.

CMOS RAM Configuration

Shows bit definitions for CMOS RAM configuration bytes.

System-Control Ports

Covers System-Control Port B (Hex 0061) and Port A (Hex 0092).

Power-On Password

Details reserved bytes for the power-on password.

Hardware Compatibility

Lists compatible interfaces and components.