Datasheet

R
Datasheet 13
Intel
®
855GM Chipset GMCH Features

Processor/Host Bus Support
⎯ Intel® Pentium® M processor and Intel®
Celeron® M processor
⎯ 2X address, 4X data
⎯ Supports 400 MHz Front Side Bus (FSB)
⎯ Supports Host bus dynamic bus inversion
(DBI)
⎯ Supports 64-bit host data bus and 32-bit
addressing
⎯ 8-deep in-order queue
⎯ AGTL+ bus driver technology with
integrated AGTL+ termination resistors and
low voltage operation (Vtt = 1.05 V)
⎯ Supports Enhanced Intel SpeedStep
®
technology (Intel Pentium M processor
⎯ Support for DPWR# signal to Intel Pentium
M processor and Intel Celeron M processor
for FSB power management

Memory System
⎯ Directly supports one DDR SDRAM
channel, 64-bits wide (72-bits with ECC)
⎯ Supports 200/266 MHz DDR SDRAM
devices with max of two, double-sided SO-
DIMMs (four rows populated) with
unbuffered PC1600/PC2100 DDR SDRAM.
⎯ Supports 128-Mbit, 256-Mbit, and 512-Mbit
technologies providing maximum capacity
of 1 GB with x16 devices and up to 2-GB
with high density 512-Mbit technology
⎯ All supported devices have four banks
⎯ Supports up to 16 simultaneous open pages
⎯ Supports page sizes of 2-kB, 4-kB, 8-kB,
and 16-kB. Page size is individually
selected for every row
⎯ UMA support only

System Interrupts
⎯ Supports Intel 8259 and front side bus
interrupt delivery mechanism
⎯ Supports interrupts signaled as upstream
memory writes from PCI and Hub interface
⎯ MSI sent to the CPU through the system bus
⎯ IOxAPIC in ICH4-M provides redirection
for upstream interrupts to the system bus

Video Stream Decoder
⎯ Improved hardware motion compensation
for MPEG2
⎯ All format decoder (18 ATSC formats)
supported
⎯ Dynamic Bob and Weave support for video
streams
⎯ Software DVD at 60 Fields/second and 30
frames/second full screen
⎯ Support for standard definition DVD (i.e.
NTSC pixel resolution of 720x480, etc.)
quality encoding at low CPU utilization

Video Overlay
⎯ Single high quality scalable overlay and
second Sprite to support second overlay
⎯ Multiple overlay functionality provided via
arithmetic stretch BLT(Block Transfer)
⎯ 5-tap horizontal, 3-tap vertical filtered
scaling
⎯ Multiple overlay formats
⎯ Direct YUV from overlay to TV-out
⎯ Independent gamma correction
⎯ Independent brightness / contrast/ saturation
⎯ Independent tint/hue support
⎯ Destination colorkeying
⎯ Source chromakeying

Multiple hardware color cursor support (32-bit
with alpha and legacy 2-bpp mode)

Accompanying I2C and DDC channels provided
through multiplexed interface

Display
⎯ Analog display support
• 350 MHz integrated 24-bit RAMDAC
that can drive a standard progressive
scan analog monitor with pixel
resolution up to 1600x1200 at 85 Hz
and up to 2048x1536 at 75 Hz
⎯ Dual independent pipe support
• Concurrent: different images and native
display timings on each display device
• Simultaneous: same images and native
display timings on each display device