VT8601 Via, VT8601 Datasheet - Page 13

• Manufacturer Part Number: VT8601
• Description: Slot-1 / Socket-370 PCI North Bridge
• Manufacturer: Via

Apollo ProMedia Core Logic Overview
Apollo ProMedia – System Media Accelerated North Bridge (SMA) – is a high performance, cost-effective and energy efficient
solution for the implementation of Integrated 2D / 3D Graphics - PCI - ISA desktop and notebook personal computer systems
from 66 MHz to 133 MHz based on 64-bit Slot-1 Intel Pentium II, Pentium III, and Celeron processors. The complete solution
consists of the Apollo ProMedia controller / “north bridge” (510 BGA) and either the VT82C596B (324 BGA) or the VT82C686A
(352 BGA) PCI-to-ISA south bridge. Both south bridges are PC98 / PC99 compliant with integrated UltraDMA-33 / 66 IDE, 4
USB ports, and a complete power management feature set. The VT82C686A also integrates HW monitoring, Super-I/O functions
(floppy disk drive interface and serial / parallel ports), and AC-97 link supporting digital audio and HSP modem functions.
Apollo ProMedia supports six banks of DRAMs up to 1GB. The DRAM controller supports standard Fast Page Mode (FP)
DRAM, EDO-DRAM, Synchronous DRAM (SDRAM), and Virtual Channel Synchronous DRAM (VC-SDRAM) in a flexible
mix / match manner. The Synchronous DRAM interface allows zero wait state bursting between the DRAM and the data buffers
at 100 MHz. The six banks of DRAM can be composed of an arbitrary mixture of 1M / 2M / 4M / 8M / 16M / 32MxN DRAMs.
The DRAM Controller is optimized to run synchronous with the CPU Front Side Bus (FSB) frequency of 66 MHz, 100 MHz, or
133 MHz.
The Apollo ProMedia also supports full AGP v1.0 capability with the internal 2D/3D Graphics Engine for maximum software
compatibility. An eight level request queue plus a four level post-write request queue with thirty-two and sixteen quadwords of
read and write data FIFO’s respectively are included for deep pipelined and split AGP transactions. A single-level GART TLB
with 16 full associative entries and flexible CPU/AGP/PCI remapping control is also provided for operation under protected mode
operating environments. Both Windows-95 VXD and Windows-98 / NT5 miniport drivers are supported.
The Apollo ProMedia supports one 32-bit 3.3 / 5V system bus (PCI) that is synchronous / pseudo-synchronous to the CPU bus.
The chip also contains a built-in AGP bus-to-PCI bus bridge to allow simultaneous concurrent operations on each bus. Five levels
(doublewords) of post write buffers are included to allow for concurrent CPU and PCI operation. For PCI master operation, forty-
eight levels (doublewords) of post write buffers and sixteen levels (doublewords) of prefetch buffers are included for concurrent
PCI bus and DRAM/cache accesses. The chip also supports enhanced PCI bus commands such as Memory-Read-Line, Memory-
Read-Multiple and Memory-Write-Invalid commands to minimize snoop overhead. In addition, advanced features are supported
such as snoop ahead, snoop filtering, L1 / L2 write-back forward to PCI master, and L1 / L2 write-back merged with PCI post
write buffers to minimize PCI master read latency and DRAM utilization. Delay transaction and read caching mechanisms are
also implemented for further improvement of overall system performance.
For sophisticated notebook implementations, the Apollo ProMedia provides independent clock stop control for the CPU /
SDRAM, PCI, and AGP buses and Dynamic CKE control for powering down of the SDRAM. A separate suspend-well plane is
implemented for the SDRAM control signals for Suspend-to-DRAM operation. Coupled with the 324-pin Ball Grid Array VIA
VT82C596A south bridge chip, a complete notebook PC main board can be implemented with no external TTLs.
Revision 1.3 September 8, 1999
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VT8601 Apollo ProMedia
System Overview