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RADIO FREQUENCY INTERFERENCE STATEMENT
This equipment generates and uses radio frequency energy and if not installed and used properly,
that is, in strict accordance with the manufacturer's instructions, may cause interference with
radio and television reception.
If this equipment does cause interference to radio or TV reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the interference by one
or more of the following measures:
* Reorient the receiving antenna.
* Relocate the computer away from the receiver.
* Move the computer away from the receiver.
* Plug the computer into a different outlet so that computer and receiver are on different
branch circuits.
* Ensure that card slot covers are in place when no card is installed.
* Ensure that card mounting screws, attachment connector screws, and ground wires are
tightly secured.
* If peripherals are used with this system, it is suggested to use shielded, grounded cables,
with in- line filters if necessary.
If necessary, the user should consult the dealer service representative for additional suggestions.
The manufacturer is not responsible for any radio or TV interference caused by unauthorized
modifications to this equipment. It is the responsibility of the user to correct such interference.
NOTE
1. When you see an error message appear on the screen after turning the power on, leave
the system switched on for one or two hours to recharge the battery. You can then
enter the system configuration.
2. Leave your system switched on for 10 to 15 hours to completely recharge the battery.
3. If you had left the system switched off for more than one month, follow step 2, above.
CONTENTS
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SECTION 1 GENERAL FEATURES
1.1 Processor and System
1.2 Memory Subsystem
1.3 I/O Subsystem
SECTION 2 INTRODUCTION
SECTION 3 SYSTEM BOARD SWITCH SETTING
3.1 System Board Switch Block Location
3.2 RAM Configuration and Installation
Utilizing 44256K DIPs
3.3 One/Zero Wait State Switch Setting
What is Zero Wait State?
SECTION 4 SYSTEM BOARD JUMPER SELECTION
4.1 DRAM Speed Selector
4.2 ROM Configuration and Installation
4.3 Display Adapter Settings
4.4 Parity Enable / Disable
What is Parity?
SECTION 5 SYSTEM BOARD CONNECTOR
5.1 P1 - Speaker Connector
5.2 P2 - Hardware Reset Connector
5.3 P3 - Turbo LED Connector
5.4 P4 - Turbo Switch Connector
5.5 P5 - Power LED and Ext-Lock Connector
5.6 P6,P7 - Power Supply Connector
5.7 P8 - External Battery Connector
5.8 KB1 - Keyboard Connector
5.9 80287 Numeric Processor Installation
SECTION 6 SYSTEM OPERATION
6.1 System BIOS
6.2 Power Up
6.3 First Time Startup
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6.4 Configuring Your System
6.4.1 Memory Test Bypass
6.4.2 Running Setup
6.5 Running AMI BIOS Diagnostics
SECTION 7 TECHNICAL INFORMATION
7.1 GC101/GC102 AT Chip Set
7.2 Fox-286 System Block Diagram
7.3 Microprocessor
7.4 System Memory Map
7.5 I/O Address Map
7.6 System Timers
7.7 System Interrupts
7.8 Direct Memory Access
7.9 Real Time Clock and CMOS RAM
7.10 Math Coprocessor
7.11 System Expansion Bus
APPENDIX
Hard Disk Drives supported by AMI BIOS
Fox-286 System Board Layout
Summary of System Board Settings
SECTION 1 GENERAL FEATURES
The Fox-286 system board is high performance system board that represents a significant
technological advance over the original 80286 designs. It offers an increased power and
flexibility architecture by supporting 80286 processor speeds up to 12 MHz(*). This manual is
designed to provide the basic information necessary for the end user to understand the Fox-286
system board.
The Fox-286 system board is designed for the most advanced computer-based applications for
today and in the future. The Fox-286 system provides a highly integrated approach to
implement a very flexible system based on the PC/AT and the 80286 CPU. Key features of the
board are summarized below:
1.1 PROCESSOR AND SYSTEM
* 16 bit 80286 CPU
* Optional 80287 numeric coprocessor
* 6/12 MHz system speed hardware/software switchable
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* 1/0 wait state hardware selectable
* On board battery backup for CMOS configuration table and real-time clock
* On board power good test circuit
(*) Note : Fox-286 is available in two models :
- Fox 286-16 and
- Fox 286-12
Specifications are the same for the two models except that FOX 286-16 operates much
faster, up to 16MHz at turbo mode and 8MHz at normal mode.
1.2 MEMORY SUBSYSTEM
* Memory Capacity:
1MB using 256K X 4 DRAM chips
* Memory Configuration:
256KB/0KB
512KB/0KB
640KB/0KB
640KB/384KB
* Parity bit can either be enabled or disabled
* ROM Capacity:
256K EPROM BIOS space for custom BIOS applications
1.3 I/O SUBSYSTEM
* Eight expansion slots
- 4 with a 36- and a 62-pin card-edge socket
- 2 with only the 62-pin card-edge socket
* Additional Features
** Hardware control support
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- Keylock
- Reset
- Turbo LED
- Power LED
- Speaker
- Wait State
- External Battery
** System support function:
- 7-Channel Direct Memory Access
- 16-level interrupt
- Three programmable timers
- System clock
SECTION 2 INTRODUCTION
The design of cost effective IBM PC/AT compatible Microcomputer requires taking advantage of
every possible advanced technology. Cost effectiveness usually can be achieved in utilizing the
least expensive parts available and the lowest counts of the required parts. The Fox-286 is
designed with top performance and flexibility in mind, it is a fully PC/AT compatible system
board implemented with the high integration G2 AT chip set which supports the 80286 CPU at
clock speeds up to 12 MHz zero wait state performance.
One main advantage of this design includes the dual clock system. This innovation make it
possible for your computer to operate at either of two clock speeds: 6 MHz or 12 MHz. In the 12
MHz zero wait-state mode, your computer will operate much faster than a conventional 80286based computer.
The board also features zero wait-state DRAM accesses in a design which supports one MByte
of DRAMs on the system board. This allows higher system performance relative to older PCAT designs. And by selection of switch setting, you can configure the RAM for the
one-wait/zero-wait option. This flexibility in configuration allows you to select an ideal
cost/performance combination.
It also provides on-board powergood source. The on- board power good generator provides a
'power-good' signal to indicate proper operation of the power supply. It allows you to used XT
grade power supply which does not provide the circuitry to generate the power good signal.
The Fox-286 system is hardware and software compatible with associated PC-AT products.
This means that virtually all the hardware and software that is available for the PC/AT can also
be run on a system you build around the Fox-286 system board.
The Fox-286 is fully software compatible with the IBM PC-AT design. The Fox-286 is
designed such that software is completely portable between the PC-AT to the Fox-286. Note that
"real-time" types of software programs could be the exception, as the higher operating speed of
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the Fox-286 could cause execution or human interface problems.
The Fox-286 supports MS-DOS Version 2.0 and above, Xenix and all PC/AT application
programs. Users can run applications designed for the PC/AT on the Fox- 286 without any
modification. Multi-tasking and multi-user capabilities are fully functional on the Fox- 286
system board.
In addition, the Fox-286 provides standard expansion bus connectors so that add-on cards
developed for the PC-AT will interface correctly.
The Fox-286 features high performance, low power consumption, low board space requirements,
reliability and low cost.
For these reasons, the Fox-286 is the ideal choice for a person seeking affordable, well designed
AT-style power.
SECTION 3 SYSTEM BOARD SWITCH
SETTING
The switches on the system board are shown in the figure below and on the following pages.
These settings are used to specify the system board memory size and zero or one wait state
operation.
Warning: Before you change any switch settings, make a note of how the switches are
presently set.
Switch Function
1 Zero/One Wait State Function
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2 Reserved
3,4 RAM Size Selection
3.1 SYSTEM BOARD SWITCH BLOCK LOCATION
The following figure shows where the switch block is on the system board.
Note: The switch settings below are for example only.
Change the switch settings by using the tip of a pen to gently pushing the switches into the
correct position.
3.2 RAM CONFIGURATION AND INSTALLATION
The Fox-286 supports 44256K DIPs for 1MB on-board memory configuration. Switch 1
selects zero-wait state or one-wait state operation. Switch 3 & 4 are set to reflect the total
amount of memory in your system. The Fox-286 system board provides four 20-pins DIP
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sockets (for 44256 DRAMs) and four 38-pins dual sockets (for either 44256 or 4464 DRAMs)
for 1 MB or 640 KB memory configuration.
Memory can be installed/split as follows:
44256K DIPs :
256KB/0KB (512KB installed)
512KB/0KB (512KB installed)
640KB/0KB (640KB installed)
640KB/384KB (1MB installed)
Utilizing 44256K DIPs
System Memory Switch Setting RAM Location/Type
256KB U3,U4,U8,U9 -44256
U2,U7(parity) -41256
512KB U3,U4,U8,U9 -44256
U2,U7(parity) -41256
U3,U4,U8,U9 -44256
640KB U2,U7(parity) -41256
U13,U14,U18,U19-4464
U12,U17(parity)-4164
U3,U4,U8,U9 -44256
640KB/384KB U13,U14,U18,U19-44256
U2,U7,U12,U17-41256
(parity)
U2, U7, U12 and U17 are the parity bits used for data checking. In normal situations, those
bits are not needed. Hence, the user can left those sockets blank and thus allowing you to
minimize the system cost.
(For more detail, please refer to the section on parity)
3.3 ONE-WAIT/ZERO-WAIT STATE SWITCH
SETTING
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What is Zero Wait State?
In a high performance PC/AT system based on the 80286 microprocessor running at its
maximum bus transfer speed, only two system clock cycles would be required for any given byte
(8-bit) or word (16-bit) transfer. The problem is that most subsystems cannot keep up with this
pace, especially at system speeds exceeding 8 MHz. This implies the need for wait states during
some accesses. Which means that the 80286 microprocessor has to wait in a do nothing loop
until memory can respond to its needs for data. For this reason, the processor has to insert wait
states. This is when the wait state comes in.
But the secret to high performance is to eliminate the wait states during the most frequent
operations. The system board DRAM accesses are the most important target for no wait state
performance. By far the most common memory or I/O cycle performed by the 80286 in an AT is
a memory access to the DRAM on the system motherboard. These are important because most
PC/AT applications spend over 90% of their time executing these types of cycles. Streamlining
these cycles is the best way to achieve high performance in a PC/AT compatible system.
To achieve a true zero-wait state in the Fox-286 system board, it has been designed such that
memory subsystem is fast enough to respond to the CPU data, and thus memory bus cycle can
be completed in just 2 cycles, eliminating the needs for wait states. This is what we refer to as
zero wait state cycle.
Switch 1 is used to select the zero-wait state or one- wait state operation. Refer to the following
figure for location of Switch 1 and the proper setting:
Zero-wait State
One-wait State
SECTION 4 SYSTEM BOARD JUMPER
SELECTION
The mainboard jumpers allow the user to select the desired system configuration. The tables
below shows the function and the default settings of these jumpers. Details of these jumpers
will be discussed in the following sections.
Jumper Function
JP1 DRAM speed selector
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JP2 BIOS ROM chip selection
JP3 Display adapter selection
JP4 Parity enable/disable
Default Settings
JP1 Pin 2,3 short
JP2 Pin 2,3 short (256K ROM BIOS)
JP3 Open (Monochrome)
JP4 Pin 2,3 short (Parity check enable)
4.1 DRAM SPEED SELECTOR
The jumper JP1 allows the user to be able to use DRAM from different sources available in the
market. This option is included in order to render superior tolerance to the wide range of
DRAM's specifications. This will ensure the highest degree of compatibility performance with
those various DRAMs' timing requirements.
The default setting for JP1 is pin 2,3 shorted. This setting should satisfy most DRAMs' timing
requirements. In case system memory is not behaving reliably, try to alter JP1 setting to pin 1,2
to solve such problem.
Refer to the figure below for the default setting.
4.2 ROM CONFIGURATION AND INSTALLATION
The Fox-286 contains sockets for two BIOS EPROMs that can either be 27128 or 27256.
Setting of jumper JP2 determines the ROM size and the type of ROM being used in the system
board. Installation of the chips is explained in the table below. No matter what BIOS is used,
the low-byte chip should be inserted in socket U20 and the high-byte chip should be inserted in
socket U21.
JP2 Type of ROM chip installation
Setting BIOS U20 U21
1-2 64KB size 27256 27256
2-3 32KB size 27128 27128
4.3 DISPLAY ADAPTER SETTINGS
The Fox-286 system can work with various display units if provided with a suitable display
adapter. Jumper JP3 is used to signal the system what type of display adapter is installed. If
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you want to use two monitors (a color monitor and a high-resolution monochrome monitor, for
example), set the adapter type to the monitor you want to use when the system boots. Refer to
the figure below for the location of jumper JP3 and the appropriate setting:
JP3 Setting Adapter Type
ON Color Graphics Adapter or
Enhanced Graphics Adapter
OFF Monochrome Adapter
4.4 PARITY ENABLE/DISABLE
What is Parity?
Parity is a method for detecting errors in data communications. The parity bit is added at the
end of a data word. The value of this bit is a function of the rest of the data word. There are
several ways that the parity bit can be calculated.
"Even parity" means that the parity bit is set so that the sum of all the bits in the data word
(including the parity bit) is even.
"Odd parity" is similar; the parity bit is set so that the sum of all the data bits in a word,
including the parity bit, is an odd number.
"No parity" means that no parity bit is added to the end of a data word.
For the Fox-286 System board, Memory Data Parity Check can either be enabled or disabled by
altering the setting of jumper JP4.
When installing DIP type RAM chips; U2, U7, U12 and U17 are the DRAM chips for the parity
bit. If data parity check is not desired, the sockets for U2, U7, U12 and U17 can be left blank;
thus enabling the user to minimize the number of RAM chips installed for the system.
For 1MB memory configuration, 41256 RAM chips are used for parity bits.
For 640KB memory configuration, 41256 RAM chips are used for BANK 0 parity bits (U2 and
U7); 4164 RAM chips are used for BANK 1 parity bits (U12 and U17).
Refer to the figure below for the location of jumper JP4, parity bits and the appropriate setting:
JP4 Setting Parity Check
1-2 Disable
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2-3 Enable
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SECTION 5 SYSTEM BOARD
CONNECTOR
This section describes with details of the hardware features in the system board. You may find
the information in this section useful. Under typical conditions, these connectors will have to
connected to the indicators and switches of the system unit.
Connector Function
P1 Speaker connector
P2 Hardware reset
connector
P3 Turbo LED connector
P4 Turbo switch connector
P5 Power LED and Ext-Lock
connector
P6,P7 Power supply connector
P8 External battery
connector
KB1 Keyboard connector
Pin assignments are as follows:
5.1 P1 - Speaker Connector
The speaker connector is a 4-pin, keyed, Berg strip. The pin assignments follow.
Pin Assignments
1 Data out
2 +5 Vdc
3 Ground
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4 +5 Vdc
5.2 P2 - Hardware Reset Connector
A reset will restarts the computer from the RAM test stage. If you encounter any problems
while using unfamiliar software, you can always restart from the beginning by pressing the
restart button.
Pin Assignments
1 Selection pin
2 Ground
5.3 P3 - Turbo LED Connector
The turbo LED indicates operation in Turbo mode (12MHz). This is a 2-pin keyed, Berg strip
(0.1") male pin connector.
Pin Assignments
1 +5Vdc
2 LED signal
5.4 P4 - Turbo Switch Connector
The operating speed of the system board can be selected by the turbo switch setting. A speed
switchover circuit ensures a smooth switchover between operating speeds, even during system
operation. Also software selection via keyboard is allowed if appropriate BIOS is used.
Hardware Select Mode:
The turbo switch changes operation mode between 12MHz and 6MHz. This setting determines
the speed at which the processor runs after booting. If you have a hardware switch on your case
panel, connect it to jumper P4. You then can push the hardware switch to enter either Normal
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mode or Turbo mode. The pin assignments are as follows:
Pin Assignments
1 Select pin
2 Ground
Software Select Mode:
In addition to setting the processor clock speed by front-panel switch (Turbo switch), you can
also change processor speed 'on-the-fly' via keyboard command. The FOX-286 has speed
switching circuitry allowing it to change speed during operation, even while you are running a
program.
The system is default to run in high speed, but the operating mode can also be changed. You
can toggle the operating speed between turbo mode and normal mode by pressing the following
keystrokes simultaneously:
[Ctrl], [Alt], [+]
or [Ctrl], [Alt], [-]
The turbo LED light will light up to show whether your computer is now running in turbo
mode or normal mode. When the Turbo LED is turned on, the system is in Turbo mode
(12 MHz). If the Turbo LED is off, the system is in Normal mode (6 MHz).
5.5 P5 - Power LED And Ext-Lock Connector
The power LED indicates whether the power is on. The keylock is used to enable or
disable the keyboard. By disabling the keyboard, the user ensures that anyone who does
not have a key will be unable to use the computer. Unlocking the keylock enables the
keyboard.
The power LED and keylock connector is a 5-pin Berg strip. Its pin assignments are as
follow:
Pin Assignments
1 LED Power
2 Key
3 Ground
4 Keyboard inhibit
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5 Ground
5.6 P6, P7 - Power Supply Connector
Pin Assignments
P6: 1 Ground
2 Ground
3 -5 Vdc
4 +5 Vdc
5 +5 Vdc
6 +5 Vdc
P7: 1 Power good
2 +5 Vdc
3 +12 Vdc
4 -12 Vdc
5 Ground
6 Ground
5.7 P8 - External Battery Connector
This is for connecting four size "AA" batteries instead of the on-board battery to the
CMOS RAM. This feature provides the same function as the on-board batteries.
Pin Assignments
1 6 Vdc
2 N/C
3 Ground
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4 Ground
5.8 KB1 (DIN Connector) - Keyboard Connector
The keyboard connector is a five-pin DIN 90-degree printed circuit board (PCB) mounting.
The pin assignments are as follows:
Pin Assignments
1 Keyboard clock
2 Keyboard data
3 Spare
4 Ground
5 +5 Vdc
5.9 80287 Numeric Processor Installation
If you use certain applications or programming languages, you may want to install a math coprocessor to enhance the performance of your system. Be ware, however, that your application
program must be specifically designed to take advantage of the math co- processor to benefit
from its presence in the system.
The 80287 Numeric Processor operates in conjunction with the 80286 CPU and will enhance the
system's math capabilities. To install the 80287, simply insert the LSI chip into the empty
socket (U30) below the power connector.
Important
Each pin on this LSI has a unique function. The 80287 should therefore be inserted into the
socket in the correct direction. If it is inserted incorrectly, the LSI or the computer may be
damaged. Install the LSI correctly by referring to the illustration. Care should be taken not to
bend and damage any of the pins. When inserting the LSI into the socket, apply force evenly
over the LSI body.
SECTION 6 SYSTEM OPERATION
6.1 SYSTEM BIOS
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All microcomputer systems use a Basic Input Output System. This is software that has been
permanently recorded in a ROM (Read Only Memory) chip and functions as the basic point of
communication between the system board and the rest of the computer.
The BIOS provides an operational interface to the system and relieve the programmer from
worrying about the characteristics of hardware devices. Thus, hardware modifications and
enhancements become transparent to user's programs, access to BIOS is through the program
interrupts of the 80286 microprocessor. Each BIOS entry point is available through its own
interrupt.
6.2 POWER UP
Upon your turning on the power of your FOX-286 system, the system will go through a self-test
routine which checks all of its internal devices. Complete testings will be carried out on the CPU,
base 640K RAM, extended RAM, ROM, system board, CMOS memory, video controllers,
parallel and serial subsystems, floppy and fixed disk subsystems and the keyboard.
When the self-test is completed, the system will search for the DOS (disk operating system)
system file in drive A. If no system diskette is put in drive A, it will check the fixed disk (if
installed).
6.3 FIRST TIME STARTUP
If it is the first time that the computer is started up, you will need to configure the system by
telling the SETUP program what hardware configuration your system contains.
6.4 CONFIGURING YOUR SYSTEM
The AMI BIOS, in addition to the BIOS program itself, contains a setup program that is called
up everytime the system boots up. This is called the SETUP. The SETUP program lets you
specify your system's configuration of diskette drives, hard disk drives, video display, memory,
and date and time. The AMI BIOS provides a one-screen interactive equipment and machine
configuration setup. The SETUP can be run after the system has been turned on and the
memory test is finished or has been escaped. The SETUP program is built-in, you do not need a
diskette to use it.
If your FOX-286 is already installed in a working system, you will not need to use the SETUP
program unless the configuration already recorded in the on- board CMOS RAM is lost or a
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change is made in your system hardware configuration. If the information is lost due to loss of
battery power, you will need to reenter the configuration. If the configuration is altered, the
changes must be recorded.
6.4.1 Memory Test Bypass
After the system is powered on or after a reset, the BIOS performs diagnostics of the system and
displays the size of the memory being tested.
Note that you can bypass the memory test by pressing the <ESC> key. This option would be
useful when the memory on the system is quite large. You may hit the <ESC> key when the
message following message appears on the screen:
Press <ESC> Key to bypass MEMORY test
6.4.2 Running Setup
Follow the instructions as they come up on the screen to complete the procedure. The initial
prompt on the screen tells you to press the <DEL> key if you want to use the setup program.
It is displayed briefly just after the RAM test is run when you first turn on the system. If it
disappears before you have a chance to respond turn the system off and on again or reset the
system and the message will reappear. The initial screen prompt will be similar to:
Press <DEL> key if you want to run SETUP or DIAGS.
Hit <DEL> key to get into the Setup Mode. (Note that <DEL> key will get you into the setup
mode, only when the above message is displayed on the screen.)
Upon your pressing of the <DEL> key, the following message will appear on the screen :
EXIT FOR BOOT
RUN CMOS SETUP
RUN DIAGNOSTICS
Use <Up> and <Down> keys to highlight the selected item. Highlight RUNCMOSSETUP for
the SETUP program and press the <Return> key to enter this option.
In a moment, the following SETUP menu will appear :
Once you have entered the SETUP menu, enter the date, time, the primary display type, the
floppy drive installed and the hard disk drive type (if installed). See Appendix1 for a printed
list of hard disk drive types. The SETUP program will automatically determines your
computer's memory configuration and displays it on the SETUP menu.
Use the <Up>, <Down> , <Left>, <Right>, and Return keys to move between options. The
field shown in reverse video is the current field, which is the one the user may changes. Then
use <PgUp> and <PgDn> keys to select the correct values.
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After you have entered the correct values to all of the SETUP options, you may now exit the
SETUP program. To do so, press <ESC> key to exit. The following message will then
appear :
Write data into CMOS and exit (Y/N)?
Press Y to update the data and exit the SETUP program.
The computer now performs a cold boot (equivalent to turning the power off and back on again),
performs the memory test, and then tries to boot from the disk drive. If your hard disk has not
yet been initialized, be sure that you have a bootable DOS diskette in the A drive.
6.5 RUNNING AMI BIOS DIAGNOSTICS
Following the above procedures until the following display is shown on the screen :
EXIT FOR BOOT
RUN CMOS SETUP
RUN DIAGNOSTICS
Use the <Up> & <Down> to move the highlight bar to select "RUN DIAGNOSTICS" and
then press <Enter>. The following screen will then appear :
The AMI Utilities includes services for the hard disk, floppy, keyboard, video and miscellaneous.
It provides an easy to operate screen-menu allowing inexperienced users to operate the program.
Simply press
<Left> or <Right> and <Up> or <Down> keys to move the highlight bar the option desired.
SECTION 7 TECHNICAL
INFORMATION
This section provides the technical materials about the FOX-286 system board. The information
in this section is for reference, and is intended for advanced readers who needs to understand the
basic design and operation of the FOX-286 system.
7.1 GC101/GC102 AT CHIP SET
The GC101 Peripheral Controller is the heart of the three chip system and forms most of the
control circuits and "glue" logic of the AT architecture in a single CMOS VLSI chip.
The GC101 performs CPU and peripheral support functions including the following:
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* All Peripheral Devices and Refresh Counters
* All mega functions
-82284 Clock Generator
-82288 Bus Controller
-8254 Timer
-8259 Interrupt Controller (2)
-8237 DMA Controller
The GC102 may be configured as either an Address Buffer or Data Buffer by strapping one pin
high or low. This chip replaces address buffer, data transceivers, memory drivers, parity
generators and supporting circuitry.
GC102 Data Buffer provides:
* Buffers and latches data for the CPU expansion bus and memory
* Parity bit generation and checking
* Slew rate controlled outputs
GC102 Address Buffer provides:
* Address buffering for expansion bus, local I/O bus and DRAM address bus.
* 10 bit DRAM address bus
7.2 FOX-286 SYSTEM BLOCK DIAGRAM
7.3 MICROPROCESSOR
The 80286 is a high-performance microprocessor with a 16-bit external data path, up to 16
megabytes of directly addressable physical memory and up to one gigabyte of virtual memory
space. The operating speed of the 80286 chip is 8 MHz in Normal mode and 16 MHz in Turbo
mode.
The 80286 operates in two modes: protected virtual address and real address.
Virtual address mode
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The virtual address mode provides a 1-gigabyte virtual address space mapped onto a 16
megabyte physical address space. Virtual address space is larger than physical address space,
and the use of a virtual address that does not map to a physical address location will cause a
restartable interrupt.
This mode uses 32-bit pointers that consist of a 16-bit selector and offset components. The
selector specifies an index into a memory-resident table, and the 24 bit base address of the
desired segment is obtained from the memory table. A 16-bit offset is added to the segment
base address to form the physical address. The microprocessor automatically references the
tables whenever a segment register is loaded with a selector. Instructions that load a segment
register will refer to the memory-based tables without additional program support. The
memory-based tables contain 8-byte values called descriptors.
Real address mode
In this mode, physical memory is a contiguous array of up to 1 megabyte. The selector portion
of the pointer is interpreted as the upper 16 bits of a 20-bit address, and the remaining 4 bits are
set to zero. This mode of operation is compatible with the 8088 and 8086.
Segments in this mode are 64KB in size and may be read, written or executed. An interrupt may
occur if data operands or instructions attempt to wrap around the end of a segment. In this
mode, the information contained in the segment does not use the full 64KB, and the unused end
of the segment may be overlay by another segment to reduce physical memory requirements.
7.4 SYSTEM MEMORY MAP
7.5 I/O ADDRESS MAP
I/O Address Map on System Board
I/O address hex 000 to 0FF are reserved for the system board I/O.
I/O Address Map on the I/O slots
I/O address hex 100 to 3FF are available on the I/O channel.
7.6 SYSTEM TIMERS
The system has three programmable timer/ counters controlled by the timer/counter from the
GC101 chip set and are defined as channels 0 through 2 :
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Note: Channel 1 is programmed to generate a 15-micro- second period signal.
The 8254 Timer/Counter is treated by system programs as an arrangement of four programmable
external I/O ports. Three are treated as counters, the fourth is a control register for mode
programming.
7.7 SYSTEM INTERRUPTS
Sixteen levels of system interrupts are provided by the 80286 NMI and two 8259 Interrupt
Controller within the GC101 chip set. The following shows the interrupt- level assignments in
decreasing priority.
7.8 DIRECT MEMORY ACCESS (DMA)
The system supports seven DMA channels. Two DMA Controller are included in the GC101,
with four channels for each chip. The DMA channels are assigned as follows:
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The following shows the addresses for the page register.
7.9 REAL TIME CLOCK AND CMOS RAM
The CMOS RAM Chip (146818) contains the real-time clock and 64 bytes of CMOS RAM, it
keeps configuration information when power is off. Upon you turn the system power on,
CMOS will load the recorded configuration into the system so that the system can function in the
right track with the equipped components. However, if you haven't configured the CMOS, or
the battery which supports the power to the CMOS is weaken, you need to redefine the necessary
parameters whenever the system is booting up.
The program of the CMOS setting will be loaded into the system automatically from the subsystem named BIOS. The following table shows the CMOS RAM addresses.
CMOS RAM Address Map
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* These bytes are not included in the checksum calculation and are not part of the
configuration record.
Real-time Clock Information
The following table describes real-time clock bytes and specifies their addresses.
Note: The setup program initializes registers A, B, C, and D when the time and date are set.
Also Interrupt 1A is the BIOS's interface to read/set the time and date. It initializes the status
bytes the same as the setup program.
7.10 MATH COPROCESSOR
The 80287 Math Coprocessor enables the FOX-286 system to perform high-speed arithmetic,
logarithmic functions, and trigonometric operations with extreme accuracy.
The coprocessor works in parallel with the microprocessor. The parallel operation decrease
operating time by allowing the coprocessor to do mathematical calculations while the
microprocessor continues to do other functions.
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The Mathematics Coprocessor, 80287 is treated as an I/O device through I/O port address hex
0F8, 0FA and 0FC. The microprocessor sends OP codes and operands through these I/O ports.
The microprocessor also receives and stores results through the same I/O ports. The "BUSY"
signal generated by the coprocessor signifies to the microprocessor to wait until the coprocessor
has finished executing.
The following describe the mathematics coprocessor control ports:
0F0 The latched Mathematics Coprocessor busy signal can be cleared with an 8- bit, Out
command, to port F0. The coprocessor will latch "BUSY", if it asserts its error signal.
Data output should be zero.
0F1 The Mathematics Coprocessor will reset to real address mode which is in the 8087
compatible if an 8-bit Out command is sent to port F1. Again, the data output should be
zero.
7.11 SYSTEM EXPANSION BUS
The FOX-286 provides drive for up to eight XT- compatible cards (six of which can be ATcompatible with the second connector)
The I/O channel supports:
* I/O address space from hex 100 to hex 3FF
* Selection of data access (either 8 or 16 bit)
* 24 bit memory addresses (16MB)
* Interrupts
* DMA channels
* Refresh of system memory from channel microprocessors
There are eight 62-pin (JA1-JA8) and six 36-pin (JB1- JB6) edge connector sockets for I/O
channel adapter cards. In two positions, the 36-pin connector is not present. These positions
can support only 62-pin I/O bus adapters.
The following figure shows the pin numbering for I/O channel connectors JA1 to JA8.
The following figure shows the pin numbering for I/O channel connectors JB1-JB6.
The following table summarize pin assignments for the I/O channel connectors.
I/O Channel (A-Side, JA1-JA8)
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I/O Channel (B-Side, JA1-JA8)
I/O Channel (C-Side JB1-JB6)
I/O Channel (D-Side JB1-JB6)
APPENDIX
Hard Disk Drives supported by AMI BIOS
Write Landing
Type Cylinders Head Precomp Zone Capacity
1 306 4 128 305 10MB
2 615 4 300 615 21MB
3 615 6 300 615 31MB
4 940 8 512 940 64MB
5 940 6 512 940 48MB
6 615 4 None 615 21MB
7 462 8 256 511 31MB
8 733 5 None 733 31MB
9 900 15 None 901 115MB
10 820 3 None 820 21MB
11 855 5 None 855 36MB
12 855 7 None 855 51MB
13 306 8 128 319 21MB
14 733 7 None 733 44MB
15 Reserved
16 612 4 All 663 21MB
17 997 5 300 997 42MB
18 997 7 None 997 58MB
19 1024 7 512 1023 61MB
20 733 5 300 977 31MB
21 733 7 300 732 42MB
22 733 5 300 733 31MB
23 306 4 All 336 10MB
24 925 7 All 925 56MB
25 925 9 None 925 72MB
26 754 7 754 754 46MB
27 754 11 None 754 72MB
28 699 7 256 699 46MB
29 923 10 None 823 71MB
30 918 7 918 918 55MB
31 1024 111 None 1024 98MB
32 1024 15 None 1024 133MB
33 1024 5 1024 1024 44MB
34 612 2 128 612 10MB
35 1024 9 None 1024 80MB
36 1024 8 512 1024 71MB
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37 615 8 128 615 42MB
38 987 3 987 987 25MB
39 987 7 987 987 60MB
40 820 6 820 820 42MB
41 977 5 977 977 42MB
42 981 5 981 981 42MB
43 830 7 512 830 50MB
44 830 10 None 830 72MB
45 917 15 None 918 115MB
46 1224 15 None 1223 152MB
47 USER TYPE
FOX-286 SYSTEM BOARD LAYOUT
SUMMARY OF SYSTEM BOARD SETTINGS
Switch 1 Function
ON Zero wait state
OFF One wait state
Switch Setting
3 4 Memory configuration
Using 44256K DIPs :
ON ON 256KB / 0KB
OFF ON 512KB / 0KB
ON OFF 640KB / 0KB
OFF OFF 640KB / 384KB
Jumper PinFunction
JP1 2,3 DRAM speed selector
(default)
JP2 1,2 256K ROM BIOS
2,3 128K ROM BIOS
JP3 short CGA / EGA / VGA
open Monochrome
JP4 1,2 Parity bit disable
2,3 Parity bit enable
Connector Function
P1 Speaker connector
P2 Hardware reset connector
P3 Turbo LED connector
P4 Turbo switch connector
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P5 Power LED & Ext-Lock connector
P6, P7 Power supply connector
P8 External battery connector
KB1 Keyboard connector
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