The AN430TX motherboard may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current characterized
errata are documented in the AN430TX Motherboard Specification Update.
Revision History
Revision
-001
Revision HistoryDate
First release of the AN430TX Motherboard Technical Product Specification.4/97
This product specification applies only to standard AN430TX motherboards with BIOS
identifier AN430TX0.86A.
Changes to this specification will be published in the AN430TX Motherboard
Specification Update before being incorporated into a revision of this document.
Information in this document is provided in connection with Intel products. No license, express or implied, by estoppel or
otherwise, to any intellectual property rights is granted by this document. Except as provided in Intel’s Terms and Conditions of
Sale for such products, Intel assumes no liability whatsoever, and Intel disclaims any express or implied warranty, relating to
sale and/or use of Intel products including liability or warranties relating to fitness for a particular purpose, merchantability, or
infringement of any patent, copyright or other intellectual property right. Intel products are not intended for use in medical, life
saving, or life sustaining applications.
Intel retains the right to make changes to specifications and product descriptions at any time, without notice.
The AN430TX may contain design defects or errors known as errata which may cause the product to deviate from published
specifications. Current characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications before placing your product order.
†
Third-party brands and names are the property of their respective owners.
Copies of documents which have an ordering number and are referenced in this document, or other Intel literature, may be
obtained from:
Intel Corporation
P.O. Box 7641
Mt. Prospect, IL 60056-7641
or call in North America 1-800-879-4683, Europe 44-0-1793-431-155, France 44-0-1793-421-777,
Germany 44-0-1793-421-333, other Countries 708-296-9333.
Copyright 1997, Intel Corporation. All rights reserved.
The motherboard is designed to fit into a standard ATX form factor chassis. Figure 2 illustrates the
form factor for the motherboard. The location of the I/O connectors and mounting holes are in
strict compliance with the ATX specification (see Section 5.1).
9.04
8.95
8.05
2.85
0.25
0.0
0.65
0.0
3.10
4.90
Figure 2. Motherboard Dimensions
11.35
11.10
OM06161
10
Motherboard Description
1.4 I/O Shield
The back panel I/O shield for the AN430TX motherboard must meet specific dimensional and
material requirements. Computers based on this motherboard need the back panel I/O shield in
order to pass certification testing. Figure 3 shows the critical dimensions for the I/O shield and
indicates the position of each cutout. The example shown is chassis-specific and will not
necessarily work with other chassis types.
4.610
1.590
0.295
1.955
0.133
0.597
0.200
0.478
1.407
0.458
0.768
1.158
0.671
0.395
0.553
0.990
1.911
2.184
3.327
4.735
4.899
0.193
Note: Material = 0.010 ±.0.001 Thick Stainless Steel, Half Hard
• Pentium processors operating at 90, 100, 120, 133, 150, 166, and 200 MHz
• Pentium processors with MMX technology operating at 166, and 200 MHz
An onboard voltage regulator derives the necessary voltage from the computer’s power supply and
enables use of standard or VRE-specified processors. The motherboard automatically detects the
type of processor (Pentium processor or Pentium processor with MMX technology).
CAUTION
If you use clips to secure a heat sink
to the processor, do not use bail-wire
style heat sink clips, such as the type
shown in the figure to the right.
These clips have been known to
damage the motherboard when
installed or removed incorrectly.
1.5.1 Microprocessor Upgrade
The motherboard has a 321-pin Socket 7 zero insertion force (ZIF) microprocessor socket.
Socket 7 supports upgrades to higher performance Pentium OverDrive processors not supported by
Socket 5.
12
Motherboard Description
1.6 Memory
1.6.1 Main Memory
The motherboard has two 168-pin DIMM sockets. Memory can be installed in one or two sockets.
Minimum memory size is 8 MB. Maximum memory size is 256 MB. The BIOS automatically
detects memory type, size, and speed so no jumper settings are required.
• Single- or double-sided DIMMs in the following sizes:
DIMM SizeTypeConfigurationTechnology
8 MB60 ns EDO1M x 6416 Mbit
16 MB60 ns EDO2M x 6416 Mbit
32 MB60 ns EDO4M x 6416 Mbit
64 MB60 ns EDO8M x 6416 Mbit
8 MBCAS Latency 2 SDRAM1M x 6416 Mbit
16 MBCAS Latency 2 SDRAM2M x 6416 Mbit
32 MBCAS Latency 2 SDRAM4M x 6416 Mbit
64 MBCAS Latency 2 SDRAM8M x 6464 Mbit
128 MBCAS Latency 2 SDRAM16M x 6464 Mbit
Memory type, size, and speed can vary between sockets, so EDO and SDRAM can be installed on
the same motherboard. Parity (x 72) DIMMs can be installed but are not recommended for the
following reasons:
• The motherboard does not provide parity checking or ECC
• Parity DIMMs cause excessive capacitive loading on memory data and address lines
1.6.1.1 EDO DRAM
EDO DRAM improves memory read performance by holding the memory data valid until the next
CAS# falling edge, unlike fast page mode DRAM, which tri-states the memory data when CAS#
negates to precharge for the next memory cycle. With EDO DRAM, the CAS# precharge overlaps
the data-valid time, which allows CAS# to negate earlier while still satisfying the memory datavalid window.
Synchronous DRAM (SDRAM) is designed to improve main memory performance. Unlike fast
page or EDO DRAM, SDRAM is synchronous with the memory clock. This simplifies the timing
design and increases memory speed because all timing is dependent on the number of memory
clock cycles. SDRAM DIMM should meet the Intel 4-clock 66 MHz 64-bit unbuffered SDRAM
DIMM v1.0 specification.
CAUTION
The board does not support SDRAM DIMMs with an n x 4 DRAM base due to loading anomalies.
For example, a DIMM that uses sixteen 16 Mbit x 4 devices should not be used.
NOTE
✏
The AN430TX supports unbuffered, 4-clock 3.3V SDRAM DIMMs only. Buffered, 5V, or 2-clock
SDRAM DIMMs cannot be used.
1.6.2 Second Level Cache
The 512 KB direct-mapped write-back L2 cache consists of two 64K x 32 global write enable
(GWE) pipeline burst asynchronous RAMs (PBSRAMs) and a 32K x 8 external tag SRAM. These
devices are soldered to the motherboard.
1.7 Chipset
The Intel 82430TX PCIset consists of the 82439TX System Controller (MTXC) device and the
82371AB PCI ISA IDE Xcelerator (PIIX4) device.
1.7.1 82439TX System Controller (MTXC)
The MTXC integrates the cache and main memory DRAM control functions and provides bus
control to handle transfers between the processor, cache, main memory, and the PCI bus. The
MTXC allows PCI masters to achieve full PCI bandwidth by using the snoop ahead feature. For
increased system performance the MTXC integrates posted write and read prefetch buffers. The
MTXC comes in a 324-pin MBGA package that features:
• Microprocessor interface control
• Integrated L2 write-back cache controller
Supports pipeline burst SRAM
64 MB maximum DRAM cacheability
Direct mapped organization—write back only
Cache hit read/write cycle timings at 3-1-1-1
Back to back read/write cycles at 3-1-1-1-1-1-1-1
14
Motherboard Description
• Integrated DRAM controller
8 MB to 256 MB main memory
64-Mbit DRAM/SDRAM technology support
3.3V EDO and unbuffered synchronous DRAM support
Non-parity (x64) support only
• Fully synchronous minimum latency PCI bus interface
PCI compliance (see Section 5.1 for compliance level)
30 and 33 MHz bus speeds
PCI to DRAM data throughput at greater than 100 MB/sec
Up to four PCI masters in addition to the PIIX4
• Power management control
Provides PCI CLKRUN# signal to control memory clock on the PCI bus (on/off)
Internal clock control (gated off if no host or PCI bus activity)
1.7.2 82371AB PCI ISA IDE Xcelerator (PIIX4)
The Intel 82371AB PCI ISA IDE Xcelerator (PIIX4) is a multifunction PCI device implementing a
PCI to ISA bridge, PCI IDE functionality, a Universal Serial Bus (USB) host/hub function, and
Enhanced Power Management. The PIIX4 comes in a 324-pin MBGA package that features:
• Multifunction PCI to ISA bridge
Supports the PCI bus at 30 and 33 MHz
PCI compliant (see section 5.1 for compliance level)
Full ISA or extended I/O (EIO) bus support
• USB controller
Two USB ports (see section 5.1 for compliance level)
Supports legacy keyboard and mouse
Supports UHCI design guide revision 1.1 interface
• Integrated dual-channel enhanced IDE interface
Support for up to four IDE devices
PIO Mode 4 transfers at up to 14 MB/sec
Supports “Ultra DMA/33” synchronous DMA mode transfers up to 33 MB/sec
Integrated 8 x 32-bit buffer for bus master PCI IDE burst transfers
Bus master mode
• Enhanced DMA controller
Two 8237-based DMA controllers
Supports PCI DMA with three PC/PCI channels and distributed DMA protocols
Fast type-F DMA for reduced PCI bus usage
• Interrupt controller based on 82C59
Support for 15 interrupts
Programmable for edge/level sensitivity
• Power management logic
Sleep/resume logic
Supports thermal alarm
Support for wake on modem through Ring Indicate input
• Real-Time Clock
256 byte battery-backed CMOS SRAM
Includes date alarm
• 16-bit counters/timers based on 82C54
1.7.3 Universal Serial Bus (USB) Support
The motherboard features two USB ports. The ports permit the direct connection of two USB
peripherals without an external hub. If more devices are required, an external hub can be
connected to either of the built-in ports. The motherboard fully supports the standard universal
host controller interface (UHCI) and uses standard software drivers that are UHCI-compatible.
Features of the USB include:
• Self-identifying, hot pluggable peripherals
• Automatic mapping of function to driver and configuration
• Support for isochronous and asynchronous transfer types over the same set of wires
• Support for up to 127 physical devices
• Guaranteed bandwidth and low latencies appropriate for telephony, audio, and other
applications
• Error handling and fault recovery mechanisms built into protocol
NOTE
✏
Computers that have an unshielded cable attached to the USB port might not meet FCC Class B
requirements, even if no device or a low speed (sub-channel) USB device is attached to the cable.
Use shielded cable that meets the requirements for high speed (fully rated) devices.
1.7.4 IDE Support
The motherboard has two independent bus mastering PCI IDE interfaces that support PIO Mode 3,
PIO Mode 4, ATA-33 (Ultra DMA/33), and ATAPI (e.g., CD-ROM) devices. The BIOS supports
Logical Block Addressing (LBA) and Extended Cylinder Head Sector (ECHS) translation modes.
IDE device transfer rate and translation mode are automatically detected by the BIOS.
Normally, programmed I/O operations require a substantial amount of processor bandwidth;
however, in true multi-tasking operating systems like Windows
mastering IDE can be devoted to other tasks while disk transfers are occurring.
1.7.4.1 LS-120 Support
LS-120 MB Diskette technology enables users to store 120 MB of data on a single, 3.5-inch
removable diskette. LS-120 technology is backward (both read and write) compatible with
1.44 MB and 720 KB DOS-formatted diskettes and is supported by Windows 95 and Windows
†
operating systems.
NT
The AN430TX motherboard allows connection of an LS-120 compatible drive and a standard
3.5-inch diskette drive. The LS-120 drive can be configured as a boot device, if selected in the
BIOS setup utility.
†
95, the bandwidth freed by bus
16
Motherboard Description
NOTE
✏
If you connect an LS-120 drive to an IDE connector and configure it as the “A” drive and
configure a standard 3.5-inch floppy as a “B” drive, the standard floppy must be connected to the
floppy drive cable’s “A” connector (the connector at the end of the cable).
1.8 Super I/O Controller
The PC87307VUL Super I/O Controller from National Semiconductor is an ISA Plug and Play
compatible (see section 5.1 for compliance level), multifunction I/O device that provides the
following features:
• Serial ports:
Two 16450/16550A-software compatible UARTs
Send/receive 16-byte FIFO
Four 8-bit DMA options for the UART with Slow Infrared Support (USI)
Ring indicator support for both serial ports
• Multimode bidirectional parallel port
Standard mode, IBM
Enhanced Parallel Port (EPP) mode with BIOS and driver support
High-speed Extended Capabilities Port (ECP) mode
• Floppy disk controller
DP8473 and N82077 compatible
16 byte FIFO
PS/2
CMOS disk input and output logic
High performance digital data separator (DDS)
PC-AT
• Keyboard and mouse controller
Industry standard 8042A compatible
General purpose microcontroller
8 bit internal data bus
• Support for an IrDA and Consumer IR-compliant infrared interface
†
diagnostic register support
†
and PS/2 drive mode support
†
and Centronics† compatible
By default, the I/O controller interfaces are automatically configured during boot up. The I/O
controller can also be manually configured in the Setup program.
1.8.1 Serial Ports
The motherboard has one 9-pin D-Sub serial port connector located on the back panel, and one
keyed 10-pin header located on the motherboard for cabling to the back panel. The 16540 and
16550A compatible UARTs support data transfers at speeds up to 921.6 Kbits/sec, while the
extended UART mode supports data rates up to 1.5 Mbits/sec.
The connector for the multimode bidirectional parallel port is a 25-pin D-Sub connector located on
the back panel of the motherboard. In the Setup program, there are four options for parallel port
operation:
• Compatible (standard mode)
• Bidirectional (PS/2-compatible)
• Bidirectional Enhanced Parallel Port (EPP) (see Section 5.1 for EPP specification compliance
level)
• Bidirectional Extended Capabilities Port (ECP)
1.8.3 Floppy Controller
The I/O controller is software compatible with the DP8473 and N82077 floppy drive controllers
and supports both PC-AT and PS/2 modes. In the Setup program, the floppy interface can be
configured for the following floppy drive capacities and sizes:
• 360 KB, 5.25-inch
• 1.2 MB, 5.25-inch
• 720 KB, 3.5-inch
• 1.2 MB, 3.5-inch (driver required)
• 1.25/1.44 MB, 3.5-inch
• 2.88 MB, 3.5-inch
1.8.4 Keyboard and Mouse Interface
PS/2 keyboard and mouse connectors are located on the back panel of the motherboard.
The 5 V lines to these connectors are protected with a PolySwitch
fuse, reestablishes the connection after an over-current condition is removed. While this device
eliminates the possibility of having to replace a fuse, power to the computer should be turned off
before connecting or disconnecting a keyboard or mouse.
NOTE
✏
You can plug the mouse and keyboard into either connector.
The keyboard controller contains the Phoenix keyboard and mouse controller code, which provides
the traditional keyboard and mouse control functions, and also supports Power On/Reset password
protection. A Power On/Reset password can be specified in the Setup program.
The keyboard controller also supports the following hot-key sequences:
• <Ctrl><Alt><Del> Software reset. This key sequence resets the computer’s software by
jumping to the beginning of the BIOS code and running the Power On Self Test (POST).
†
circuit that, like a self-healing
18
Motherboard Description
1.8.5 Infrared Support
The motherboard has a 6-pin header that supports Hewlett Packard† HSDL-1000 compatible
infrared (IR) transmitters/receivers. In the Setup program, Serial Port 2 can be directed to a
connected IR device. The connection can be used to transfer files to or from portable devices like
laptops, PDAs and printers. The Infrared Data Association (IrDA) specification supports data
transfers of 115 Kbits/sec at a distance of 1 meter. See section 5.1 for IrDA specification
compliance level.
1.8.5.1 Consumer Infrared Support
The motherboard has a dedicated signal pin that supports Consumer Infrared (IR) devices (remote
controls). The signal pin supports receive only. Consumer IR devices can be used to control
telephony functions and multimedia operations like volume and CD track changes. In this mode,
data rates of up to 685.57 Kbits/sec are supported. A software and hardware interface is needed to
use this feature.
1.9 Graphics Subsystem
The optional onboard graphics subsystem features the ATI-264GT Rage II+ graphics controller.
1.9.1 Graphics Controller
The ATI-264GT Rage II+ provides the following features:
• Drawing coprocessor that operates concurrently with the host processor
• Optional video coprocessor that enables simultaneous display of 24 bits per pixel (bpp) video
and 8 bpp graphics
• VGA
• PCI compliant
• Support for power management
• Support for VESA Display Data Channel (DDC2B)
• Video scaler, color space converter, true color palette
• Triple-clock synthesizer
• Support for ATI multimedia feature connector
• 3-D graphics capability
• PCI bus master
1.9.1.1 Video Memory
The motherboard supports 2 MB of 66MHz (15 ns burst mode cycle time) SGRAM for video
memory, soldered to the board. There are no upgrade options for video memory.
Table 1.ATI-264GT Rage II+ Maximum Refresh Rates at Different Resolutions
2 MB MemoryMaximum Refresh Rate (Hz) At:
4-bit Color
Resolution
640 x 480160160160160
800 x 600160160160160
1024 x 768160160160not supported
1152 x 864160160160not supported
1280 x 1024160160160not supported
(16 Colors)
8-bit Color
(256 Colors)
16-bit Color
(64K Colors)
24-bit Color
(16M Colors)
1.9.1.3 Graphics Drivers and Utilities
Graphics drivers and common graphics utilities are available for Windows 3.x, Windows 95, and
Windows NT. Drivers and utilities are available from Intel’s World Wide Web site (see
Section 5.2).
1.9.2 VESA/ATI Multimedia Channel Connector
The motherboard has an optional 40-pin VESA/ATI Multimedia Channel connector that uses
26 pins for the VESA standard bus and 12 pins for the ATI Enhanced Visual Architecture bus. The
connector features a shared frame buffer interface and a Local Peripheral Bus (LPB) with a
bidirectional interface that supports video companion devices like MPEG/live video decoders.
1.9.3 Brooktree Video Capture Processor
The motherboard features an optional Brooktree Bt829A Video Capture Processor for digitizing
analog NTSC/PAL/SECAM input signals from TV tuners, VCRs, cameras, and other sources of
composite or Y/C video. The Bt829A has the mixed signal circuitry required to convert an analog
composite signal into a scaled digital video stream supporting several video formats, resolutions
and frame rates. The Bt829A features include:
• Single-chip composite/S-Video NTSC/PAL/SECAM to YCrCb digitizer
• Square pixel and CCIR601 resolution for NTSC, PAL, and SECAM
• Chroma comb filtering
• Horizontal and vertical filtered scaling
• Programmable hue, brightness, saturation, and contrast
• User-programmable cropping of the video window
• 2x oversampling
• Two-wire I
• 8- or 16-bit pixel interface
• Automatic NTSC/PAL format detection
• Automatic gain control
2
C bus interface
20
Motherboard Description
The motherboard provides two inputs for video on the video riser card I/O panel: an RCA input
connector for composite video signals, and a 7-pin mini-DIN connector for S-Video signals and
2
Inter-Integrated Circuit (I
C) signals.
The Bt829A’s registers are accessed using the I
device. To reprogram the default settings, you must connect an I
2
C/S-Video connector. The I2C serial clock and data lines transfer data from the master device at
I
2
C interface. The Bt829A operates as an I2C slave
2
C master to the 7-pin mini-DIN
a rate of 100 Kbits/sec.
1.9.3.1 Video Capture Input Connector
A 1x4 pin connector is available on the motherboard for applying a composite video signal (from a
TV Tuner add-in card, for example) to the input of the Brooktree Bt829A Video Capture device.
2
Two pins are dedicated to external control capability via the I
C protocol using serial clock (SCL)
and serial data (SDA) pins.
1.9.3.2 Video Capture Drivers and Utilities
Video capture software and utilities are available from Intel’s World Wide Web site (see
Section 5.2).
1.9.4 ImpacTV NTSC/PAL Encoder
The optional ATI-ImpacTV NTSC/PAL Encoder is an ASIC that provides a TV-out interface for
the ATI-264GTB 3D Rage II+ multimedia graphics accelerators. Quality issues such as image
flicker, illegible text and low-definition graphics are controlled through on-chip circuitry for
scaling, flicker removal, and artifact suppression. Features include:
• Circuitry for producing interlaced images with flicker removed
• Circuitry for eliminating dot crawl
• Filters for bringing out detail in fine text while suppressing color artifacts
• Support for both NTSC and PAL formats
• Filters that ensure signal bandwidth does not exceed TV standards
• Fully programmable timing that enables NTSC or PAL signals to be generated from monitor
resolutions that include 320x200, 320x240, 320x350, 320x400, 360x200, 360x240, 360x400,
360x440, 512x384, 640x350, 640x400, 640x480, 720x350, 720x400, 720x480, and 800x600
• Simultaneous display of images on both a TV and a PC monitor
• Independent horizontal positioning of the TV image and the PC monitor image
• Independent vertical positioning of the TV image and the PC monitor image
• Independent horizontal scaling of the TV image and the PC monitor image
• Power management for full VESA DPMS and EPA Energy Star compliance
• Automatic power down of the ASIC at initialization if a TV is not detected
• Support for both composite and S-Video connectors
The motherboard provides two outputs for video on the video riser card I/O panel: an RCA
connector for composite video-out signals and a 4-pin mini-DIN connector for S-Video output
signals.
A video riser card is required for TV outputs and video capture inputs (shown in Figure 7).
1.10 Audio Subsystem
The onboard audio subsystem features the Yamaha OPL† YMF715, a 100-pin SQFP audio chip. It
integrates a 16-bit audio codec, OPL3 FM synthesis and its DAC, 3-D enhanced stereo controller,
and an interface for MPU-401 and a joystick. The YMF715 provides all the digital audio and
analog mixing functions needed for recording and playing sound on personal computers. It
features the following:
• Integrated 3-D enhanced stereo controller including all required analog components
• Stereo analog-to-digital and digital-to-analog converters
• Analog mixing, anti-aliasing, and reconstruction filters
• Support for 16-bit address decode
• Line, microphone, mono, and modem inputs
• ADPCM, A-law or µlaw digital audio compression/decompression
• Full digital control of all mixer and volume control functions
• Software switching between rear panel Mic In and Line In connectors
• Plug and Play compatibility
• Sound Blaster
• Pin compatible with the Yamaha YMF711
†
and Windows Sound System compatibility
The following table shows the IRQ, DMA channel, and base I/O address options for the audio
subsystem. These options are automatically chosen by the Plug and Play interface, so there are no
default settings.
IRQ
Resource
Sound Blaster
(DMA playback, DMA shared with
Windows Sound System capture)
Windows Sound System
(DMA playback)
MPU-401
(IRQ shared with Sound Blaster)
MIDI / Game Port201h
†
AdLib
(Options)
5
7
9
10
11
5
7
9
10
11
DMA Channel
(Options)
0
1
3
0
1
3
I/O Address
(Options)
220h
240h
220-280h
530h
E80h
530-F48h
330h
300h
300-334h
201-211h
388h
388-3F8h
22
Motherboard Description
1.10.1 Yamaha OPL4-ML
The Yamaha OPL4-ML wavetable is a ROM table containing live instrument sound samples.
Wave synthesis results in richer and more realistic sounds then that of FM synthesis.
1.10.2 Audio Drivers and Utilities
Audio software and utilities are available from Intel’s World Wide Web site (see Section 5.2).
1.10.3 Audio Connectors
The board has these audio connectors:
• Back panel audio jacks (Line In, Line Out, Mic In)
• CD-ROM audio connector (either standard CD or optional ATAPI styles provided)
A 1 x 4-pin connector is available for connecting the audio output of an internal CD-ROM
connector to the audio subsystem’s mixer. The connector is compatible with most cables supplied
with ATAPI CD-ROM headers designed to connect to audio add-in cards.