DFI 486-OCV Plus User Manual

486-OCV Plus
System Board
User’s Manual

- D21840429 -

v Copyright 1994, by DFI Inc.

All rights reserved.
No part of this document may be copied or reproduced

in any form or by any means without the prior written
consent of DFI, Inc.

DFI, Inc. makes no warranties with respect to this
documentation and disclaims any implied warranties of
merchantability, quality, or fitness for any particular
purpose. The information in this document is subject to
change without notice. DFI, Inc. reserves the right to
make revisions to this publication and to make changes
to any and/or all parts of its content, at any time,
without obligation to notify any person or entity of such
changes. Further, DFI, Inc. assumes no responsibility
for any errors that may appear in this document.

DFI is a registered trademark, and 486-OCV Plus is a
trademark of Diamond Flower, Inc. All other product
names mentioned are trademarks or registered trade­marks of their respective companies.

v Table of Contents v

Introduction .................................................................................

Features and Specifications .................................................

Installation Overview .................................................................

Preparing the Area ................................................................

Handling the System Board ..................................................

Tips in Handling the System Board ...............................

Hardware Installation .............................................................

Memory Installation .........................................................

Installing the Modules ..............................................

Board Configuration ........................................................

Jumper Settings .......................................................

Jumper Settings for VL-Bus Add-On Board .....

Jumper Settings of Internal/External/CMOS
Clean, Display Type and Diagnostic/

Password Clear ..................................................

Cache Configuration ................................................

Jumper Settings for Cache Memory .................

CPU Installation and Upgrade .......................................

CPU Configuration ..................................................

Jumper Settings for CPUs .................................

Installing Upgrade CPUs ........................................

Installing the System Board ..................................................

Initial Setup Program .................................................................

AMI BIOS Setup Utilities .......................................................

Standard CMOS Setup ..................................................

Advanced CMOS Setup .................................................

Auto Configuration with BIOS Defaults .........................

Auto Configuration with Power-on Defaults ..................

1-1

1-2

2-1

2-1
2-2
2-2
2-2
2-2
2-6
2-7
2-8
2-8

2-11
2-14
2-16
2-18
2-18
2-19
2-22
2-26

3-1

3-2
3-3
3-5
3-7
3-7

Change Password .........................................................

Auto Detect Hard Disk ..................................................

Hard Disk Utility .............................................................

Write to CMOS and Exit ................................................

Do not write to CMOS and Exit ....................................

3-8

3-9
3-10
3-11
3-11

Troubleshooting Checklist ......................................................

Appendix A: Types of Modules ..............................................

Appendix B: System Error Report .........................................

Appendix C: Memory & I/O Maps ...........................................

Appendix D: 16-Bit ISA I/O Pin Assignments .......................

Appendix E: VL-Bus I/O Pin Assignments ...........................

Appendix F: System Overview ...............................................

Appendix G: Connector Pin Assignments ............................

Appendix H: AMI BIOS Hard Disk Table ...............................

4-1

A-1
B-1
C-1
D-1

E-1

F-1
G-1
H-1

v Introduction

The 486-OCV Plus system board is designed so that it
may be equipped with Intel's 80486DX, 80486DX2,
80486SX, and 80486 OverDriveTM Processors which can
run from speeds of 25MHz to 66MHz. It may also use
a PentiumTM OverDrive Processor running at 50MHz or
66MHz. This Pentium-based system board is twice as
fast as the 80486DX-33 and accommodates almost all of
the existing programs designed for 386 or 486-based
systems. The system board also supports a Cyrix or
AMD 486DX CPU running at 40MHz.

The 486-OCV Plus is a jumperless-upgrade board
allowing you to easily upgrade your CPU from a 486SX
to 486DX or DX2 for example, without altering any
jumpers. However, if you change your CPU speed from
25MHz to 33MHz, 40MHz or 50MHz, or change a
Cyrix CPU to an Intel or AMD CPU, you may have to
alter a few jumpers.

The 486-OCV Plus is equipped with a Zero Insertion
Force socket to make upgrading your CPU easy. It also
supports an optional Flash EPROM. Flash EPROM is a
memory chip for the storage of BIOS which can be
erased in bulk or modified using a software utility.

486-OCV Plus

The 486-OCV Plus system board is also equipped with
two VESA compliant local bus slots. The VL-Bus of
the 486-OCV Plus system board operates at the same
frequency (up to 40MHz) and phase as the CPU, sup­porting all DMA and system I/O bus mastering cycles.

Introduction u 1-1

PentiumTM OverDrive Ready System Board

The 486-OCV Plus uses 256Kx36, 512Kx36, 1Mx36,
2Mx36, 4Mx36 and 8Mx36 HSIM modules with speeds
of at least 80ns. The memory can be configured to
twenty-one different sizes from 1MB to 64MB. The
system is equipped with two 32-bit VESA VL-Bus and
eight 16-bit ISA expansion slots.

Features and Specifications

• Intel 80486DX running at 33/40/50MHz,
80486DX2 running at 50/66MHz, 80486
OverDriveTM Processor, PentiumTM OverDrive
Processor running at 50/66MHz, or 80486SX
running at 25/33MHz

Cyrix or AMD 486DX running at 40MHz

• Uses AMI BIOS: 27512-20 (1)

• Uses OPTi 82C499 chip set

• Cache organization: direct map, write back and bank

interleave

• Supports 64K, 128K and 256K cache sizes

• Memory configurable from 1MB to 64MB

• Uses 256Kx36, 1Mx36 and 4Mx36 HSIMM

Uses 512Kx36, 2Mx36 and 8Mx36 (for Banks 0 and
2 only)

• Supports memory with parity check

• 8MHz bus clock

• Software programmable cache and DRAM wait states

• Supports system BIOS and Video BIOS Shadow

RAM function

• Supports sixteen edge triggered interrupts

• Hidden refresh or slow refresh supported

• Optional Flash memory BIOS supported

• Supports PentiumTM OverDrive Processor Zero

Insertion Force socket

• Supports one PS/2 mouse port

• An optional diagnostic LCD port

1-2 u Introduction

486-OCV Plus

• Supports VESA VL-Bus devices (2 VESA Master/
Slave)
ISA DMA Master access to local device
Local Master access to an ISA device
Fully compatible with VESA VL-Bus rev. 1.0

• Two 32-bit VL-Bus and eight 16-bit ISA slots

• Maximum card length
Full-length cards in all VL-Bus slots and in three
ISA slots

9.75" cards in three ISA slots

• Four layer PCB

• Baby AT size

• Operating temperature: 0oC - 40oC

• One year limited warranty

Warning:

If your 486-OCV Plus system board is using a 486DX
50 CPU, we recommend that you do not install any
VL-Bus devices. The VL-Bus connectors, compliant
with VESA VL-Bus standard rev. 1.0, limit the speed of
a VL-Bus device operating across the connector
(e.g. an add-on board) to 40MHz.

The table below, based on the VESA VL-Bus
specification, shows the recommended number of
installed VL-Bus devices at various CPU speeds. This
table is only a recommendation, not a requirement. Any
VL-Bus add-on board must correspond with the CPU
speed, whether it is buffered or unbuffered.

CPU Speed Unbuffered Buffered

<= 33MHz 2 slots/2 devices 3 slots/3 devices
40MHz 1 slot/2 devices not recommended
>= 50MHz 0 slot/2 devices not recommended

Introduction u 1-3

PentiumTM OverDrive Ready System Board

v Installation Overview

This chapter summarizes the steps in installing the
486-OCV Plus system board into your system unit. It
also includes a description of the area in which you must
work and directions for memory installation. Before
installing the system board, obtain the memory you plan
to install.

Preparing the Area

Before unpacking the system board, make sure the
location you have selected is relatively free of dust and
static. Excessive exposure to dust, static electricity,
direct sunlight, excessive humidity, extreme cold and
water can damage the operational capabilities of your
system board. Avoid soft surfaces such as beds and
carpeted floors which can hinder air circulation. These
areas also attract static electricity which can damage
some circuits on your system board.

Be sure that the power source has a properly grounded,
three-pronged socket. It is essential that the power
connection be properly grounded for correct functioning
of your system board. For further protection, we rec­ommend that you use a surge protection socket. This
will protect the system board from damage that may
result from a power surge on the line.

Move items that generate magnetic fields away from
your system board, since magnetic fields can also dam­age your system board. Once you have selected the
ideal location, unpack the 486-OCV Plus system board
carefully.

2-1 u Installation Overview

Handling the System Board

It is quite easy to inadvertently damage your system
board even before installing it to your system unit.
Static electrical discharge can damage computer compo­nents without causing any signs of physical damage. You
must take extra care in handling the system board to
ensure that no static build-up is present.

Tips in Handling the System Board

1) To prevent electrostatic build-up, leave the board in

its anti-static bag until you are ready to install it.

2) Wear an antistatic wriststrap.

3) Do all preparation work on a static-free surface with

components facing up.

4) Hold the system board by its edges only. Be careful

not to touch any of the components, contacts or
connections, especially gold contacts on the board.

486-OCV Plus

5) Avoid touching the pins or contacts on all modules

and connectors. Hold modules and connectors by
their ends.

Hardware Installation

Memory Installation

The 486-OCV Plus system board can support 1MB to
64MB of memory using HSIMMs. HSIMM is an
acronym for High Density Single In-line Memory Mod­ule.

Installation Overview u 2-2

PentiumTM OverDrive Ready System Board

An HSIMM consists of several RAM chips soldered
onto a small circuit board. An HSIMM connects to the
system board via a 72-pin card-edge connector.

The HSIMM sockets are divided into four banks on the
system board. The 486-OCV Plus system board uses
256Kx36, 512Kx36, 1Mx36, 2Mx36, 4Mx36 and 8Mx36
HSIM modules.

Note:

The 8Mx36 HSIM module must be the standard size
module. Mechanical problem may occur if a longer
size of module is installed.

You will need 1 to 4 pieces of HSIM modules, depend­ing on the amount of memory you intend to install.
Your system board can be configured with 1MB, 2MB,
4MB, 5MB, 6MB, 8MB, 9MB, 12MB, 13MB, 16MB,
18MB, 20MB, 24MB, 28MB, 32MB, 34MB, 36MB,
40MB, 48MB, 52MB or 64MB of onboard memory.

To install the HSIM modules, first populate Bank 0, then
Bank 1 and so on. Failure to do so will cause the
system board to work improperly.

The following table summarizes the bank locations and
modules needed for the corresponding memory sizes.
Each bank consists of 1 HSIMM socket.

2-3 u Installation Overview

486-OCV Plus

Memory Size Bank 0 Bank 1 Bank 2 Bank 3

1MB 256Kx36 - - ­2MB 256Kx36 256Kx36 - ­2MB 512Kx36 - - ­4MB 1Mx36 - - ­5MB 256Kx36 1Mx36 - ­6MB 256Kx36 256Kx36 1Mx36 ­6MB 512Kx36 - 1Mx36 ­8MB 1Mx36 1Mx36 - ­8MB 2Mx36 - - ­9MB 1Mx36 1Mx36 256Kx36 ­9MB 2Mx36 - 256Kx36 ­12MB 1Mx36 1Mx36 1Mx36 ­12MB 2Mx36 - 1Mx36 ­13MB 256Kx36 1Mx36 1Mx36 1Mx36
13MB 256Kx36 1Mx36 2Mx36 ­16MB 1Mx36 1Mx36 1Mx36 1Mx36
16MB 2Mx36 - 2Mx36 ­16MB 4Mx36 - - ­18MB 256Kx36 256Kx36 4Mx36 ­18MB 512Kx36 - 4Mx36 ­20MB 1Mx36 4Mx36 - ­20MB 4Mx36 1Mx36 - ­24MB 1Mx36 1Mx36 4Mx36 ­24MB 2Mx36 - 4Mx36 ­24MB 1Mx36 4Mx36 1Mx36 ­24MB 4Mx36 1Mx36 1Mx36 ­28MB 1Mx36 1Mx36 4Mx36 1Mx36
28MB 2Mx36 - 4Mx36 1Mx36
28MB 1Mx36 4Mx36 1Mx36 1Mx36
28MB 1Mx36 4Mx36 2Mx36 ­28MB 4Mx36 1Mx36 1Mx36 1Mx36
28MB 4Mx36 1Mx36 2Mx36 ­32MB 4Mx36 4Mx36 - ­32MB 8Mx36 - - -

Installation Overview u 2-4

PentiumTM OverDrive Ready System Board

Memory Size Bank 0 Bank 1 Bank 2 Bank 3

34MB 256Kx36 256Kx36 4Mx36 4Mx36
34MB 512Kx36 - 8Mx36 ­36MB 1Mx36 4Mx36 4Mx36 ­36MB 4Mx36 1Mx36 4Mx36 ­36MB 4Mx36 4Mx36 1Mx36 ­36MB 8Mx36 - 1Mx36 ­40MB 1Mx36 1Mx36 4Mx36 4Mx36
40MB 2Mx36 - 8Mx36 ­40MB 1Mx36 4Mx36 4Mx36 1Mx36
40MB 4Mx36 1Mx36 4Mx36 1Mx36
40MB 4Mx36 4Mx36 1Mx36 1Mx36
40MB 8Mx36 - 2Mx36 ­48MB 4Mx36 4Mx36 4Mx36 ­48MB 8Mx36 - 4Mx36 ­52MB 1Mx36 4Mx36 4Mx36 4Mx36
52MB 1Mx36 4Mx36 8Mx36 ­52MB 4Mx36 1Mx36 4Mx36 4Mx36
52MB 4Mx36 1Mx36 8Mx36 ­52MB 4Mx36 4Mx36 4Mx36 1Mx36
52MB 8Mx36 - 4Mx36 1Mx36
64MB 4Mx36 4Mx36 4Mx36 4Mx36
64MB 8Mx36 - 8Mx36 -

2-5 u Installation Overview

OPTi

82C499

Pin 1 of the HSIMM socket

Bank 0

Bank 1

Bank 2

Bank 3

Locations of the HSIMM Sockets on the System Board

Installing the Modules

486-OCV Plus

HSIMMs simply snap into a socket on the system board.
Pin 1 of the HSIMM must correspond with Pin 1 of the
socket.

Installation Overview u 2-6

PentiumTM OverDrive Ready System Board

1. Position the HSIM module above the HSIMM
socket with the chips of the module facing the center
of the system board.

2. Seat the module at an angle into the bank. Make
sure it is completely seated. Tilt the module upright
until it locks in place in the socket.

Board Configuration

The 486-OCV Plus is designed with jumpers and con­nectors onboard. Make sure that the jumpers are set
correctly before installing the system board into your
system unit.

J1

J2

J3

J4

J5

J6

J7

JP6

JP7 JP8

JP9

JP12 JP14

JP13

JP23

JP38

JP18

JP24

JP31

JP25 JP26

JP34

SL1

SL2

OPTi

82C499

Locations of Jumpers and Connector Pins

on the 486-OCV Plus System Board

2-7 u Installation Overview

JP32

JP39

JP29

J8

J10

J11

J9

Jumper Settings

Jumper Settings for VL-Bus Add-On Board

If a VL-Bus add-on board is installed in the 486-OCV
Plus system board, make sure Jumpers JP18, JP23, JP24
and JP34 are set correctly.

JP18

JP23 JP24

JP34

OPTi

82C499

486-OCV Plus

Locations of Jumpers JP18, JP23, JP24 and JP34

on the 486-OCV Plus System Board

Installation Overview u 2-8

PentiumTM OverDrive Ready System Board

Jumper JP23

High Speed Mode for VL-Bus Board

Set Jumper JP23 to Off only if the VESA VL-Bus
add-on board installed in the VL-Bus slots support Zero
Wait State. If you are not sure that your add-on
board(s) support Zero Wait State, set JP23 to On;
otherwise, a system error may occur.

On: One Wait State

Off: Zero Wait State

Jumper JP24

CPU Speed for VL-Bus Board

If a VL-Bus board is installed in the 486-OCV Plus
system board, Jumper JP24 must be set to On if the
CPU speed is greater than 33MHz. If the CPU speed is
less than or equal to 33MHz, set JP24 to Off.

On

CPU Speed > 33MHz

CPU Speed <= 33MHz

Off

2-9 u Installation Overview

486-OCV Plus

Jumper JP18

VL-Bus Ready Signal Select

If a VESA VL-Bus add-on board is installed in either
one of the VL-Bus slots and the 486-OCV Plus system
board is using a 486-50DX CPU, we recommend that
you set Jumper JP18 to "Delay 1 PCLK". Your system
board might not work properly if Jumper JP18 is set to
"No Delay".

321

1-2 On: Delay 1 PCLK

(Default)

2-3 On:

No Delay

321

Jumper JP34

VL-Bus Address Select

If the 486-OCV Plus system board is using a 40MHz or
50MHz 486DX CPU, VESA VL-Bus add-on boards
may not work when Jumper JP34 is set to "No Delay".
In this case, we recommend that you set Jumper JP34
pins 1-2 and 3-4 to On, "Delay 1 PCLK".

Set JP34 pins 2-3 to On if your system board is using a
386-25/33/40MHz or 486-25/33MHz CPU. If it is not
set to these recommended settings, your system might
hang.

21 3 4

1 4

2 3

1-2, 3-4 On:

Delay 1 PCLK

Installation Overview u 2-10

2-3 On: No Delay

(Default)

PentiumTM OverDrive Ready System Board

* If Jumper JP34 is set to Delay 1 PCLK, the 486-OCV

Plus will only support one VL-Bus Master in Slot
SL2.

Jumper Settings of Internal/External/CMOS Clean, Display Type
and Diagnostic/Password Clear

Jumper J11 enables or disables the internal battery,
external battery or CMOS Clean. JP29 allows you to
select between a color or monochrome display. JP39
allows you to perform diagnostic test and clear the
password.

JP39

JP29

OPTi

82C499

Locations of Jumpers J11, JP29 and JP39

on the 486-OCV Plus System Board

2-11 u Installation Overview

J10

J11

486-OCV Plus

Jumper J11

Internal Battery/CMOS Clean Select

The 486-OCV Plus comes with an internal battery. If
there is a problem with the internal battery, or if you
prefer to connect an external battery, set Jumper J11
pins 1-2-3 to Off and connect an external battery to
Connector J10.

321

1-2-3 Off: External Battery Enable

(Default)

If, for some reason, the CMOS becomes corrupted, the
system can be reconfigured with the default values
stored in the ROM chips. To load the default values, set
J11 pins 2 and 3 to On for approximately one to two
days, then return to the default position.

1-2 On:

321

2-3 On: CMOS Clean

321

Internal Battery Enable

Note:

After CMOS has been reset, you must either set the
jumper to Internal or External battery enable. If you
set the jumper to External battery enable, make sure
you connect an external battery to Connector J10.

Installation Overview u 2-12

PentiumTM OverDrive Ready System Board

Jumper JP29

Display Type Select

Jumper JP29 sets the display adapter to color or mono.
This jumper must match the type of display adapter
installed. If you change your video adapter, make sure
that this jumper is changed accordingly.

On: Color Display

Off: Mono Display

(Default)

Jumper JP39

Diagnostic/Password Clear

If you had enabled the Password Checking Option in the
Advanced CMOS Setup and forgot your password, set
Jumper JP39 to On. The 486-OCV Plus system board
will perform diagnostic test and clear the password
stored in your CMOS. Set JP39 to Off after you have
cleared the password.

On: Diagnostic/

Password Clear

Off: Normal

(Default)

2-13 u Installation Overview

Cache Configuration

The 486-OCV Plus system board can be configured to
three different cache sizes: 64KB, 128KB and 256KB.
128KB of cache memory is the default size. Either
8K x 8 (20ns) or 32K x 8 (20ns) chips are used for
cache depending on the size of cache desired. Regard­less of the amount of cache memory installed, one 8K x
8 (20ns), one 16K x 8 or one 32K x 8 (20ns) SRAM is
needed for tag RAM to store the cacheable addresses.
Because only one SRAM is installed for tag RAM, the
cacheable system RAM size is dependent on the size of
cache installed on your system board. The system board
can automatically detect the cacheable system RAM size
based on the size of cache installed in the 486-OCV Plus
system board.

The following table summarizes the cacheable system
RAM size for the corresponding cache size.

Cache Memory Cacheable System RAM Size

486-OCV Plus

64KB 16MB and below
128KB 32MB and below
256KB 64MB (maximum memory)

Important:

When cache size is 64KB or 128KB, an 8K x 8 (20ns)
SRAM should be inserted in socket U3 for tag RAM.
When cache size is 256KB, use a 16K x 8 or 32K x 8
(20ns) SRAM.

Installation Overview u 2-14