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**82395SX Smart Cache 12/17/90
***Notes:...
**82396SX Smart Cache 12/17/90...
**82485 Turbo Cache (and 485Turbocache) c90...
**82489DX Advanced Programmable Interrupt Controller 10/12/92...
**82495DX/490DX DX CPU-Cache Chip Set <Sep91...
**82495XP/490XP Cache Controller / Cache RAM (for i860) 06/05/91...
**82496/491 Cache Controller / Cache RAM (for P5 Pentium) 03/22/93...
**82497/492 Cache Controller / Cache RAM (for P54 Pentium) <Nov94...
**82498/493 Cache Controller / Cache RAM (for P54 Pentium) <Nov94...
**
**Later chipsets (basic spec):
**440 series:
***440FX (Natoma) 05/06/96...
***440LX (Balboa) 08/27/97...
***440BX (Seattle) c:Apr'98...
***440DX (?) c:?...
***440EX (?) c:Apr'98...
***440GX (Marlinespike) 06/29/98...
***440ZX & 440ZX-66 (?) 01/04/99...
***440ZX-M (?) 05/17/99...
***440MX (Banister) 05/17/99...
**450NX (?) 06/29/98:...
**????? (Profusion) c:99...
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*SIS...
**5571 (Trinity) Pentium PCI/ISA Chipset (75MHz) <12/09/96
***Info:
[no general section in datasheet]
3. Functional Description
3.1 DRAM Controller
3.1.1 DRAM Type
The SiS5571 can support up to 384MBytes (3 banks) of DRAMs and each
bank could be single or double sided 64 bits FP (Fast Page mode) DRAM,
EDO (Extended Data Output) DRAM, and SDRAM (Synchronous DRAM)
DRAM. Half populated bank(32-bit) is also supported.
The installed DRAM type can be 256K, 512k, 1M, 2M, 4M or 16M bit deep
by n bit wide DRAMs, and both symmetrical and asymmetrical type DRAM
are supported. It is also permissible to mix the DRAMs (FP/EDO/SDRAM)
bank by bank and the corresponding DRAM timing will be switched
automatically according to register settings.
3.1.2 DRAM Configuration
The SiS5571 can support single sided or double sided DRAM modules for
each bank. The basic configurations are shown as the following:
3.1.3 Double-sided DRAM [omitted see datasheet]
3.1.4 Single-sided DRAM [omitted see datasheet]
3.1.5 DRAM Scramble Table [omitted see datasheet]
3.1.6 64-bit mapping table [omitted see datasheet]
3.2 DRAM Performance [omitted see datasheet]
3.3 CPU to DRAM Posted Write FIFOs
There is a built-in CPU to Memory posted write buffer with 8 QWord
deep ( CTMFF). All the write access to DRAM will be buffered. For the
CPU read miss / Line fill cycles, the write- back data from the second
level cache will be buffered first, and right after the data had been
posted write into the FIFO, CPU can performs the read operation by the
memory controller starting to read data from DRAMs. The buffered data
are then written to DRAM whenever no any other read DRAM request
comes. With this concurrent write back policy, many wait states are
eliminated. If there comes a bunch of continuous DRAM write cycles,
some ones will be pending if the CTMFF is full.
3.4 32-bit (Half-Populated) DRAM Access
For the read access, there will be either single or burst read cycle
to access the DRAM which depends on the cacheability of the cycle. If
the current DRAM configuration is half-populated bank, then the
SiS5571 will assert 8 consecutive cycles to access DRAM for the burst
cycle. For the single cycle that only accesses DRAM within a DWord,
the SiS5571 will only issue one cycle to access DRAM. For the single
cycle that accesses one Qword or cross DWord boundary, the SiS5571
will issue two consecutive cycles to access DRAM.
3.5 Arbiter
The arbiter is the interface between the DRAM controller and the host
which can access DRAMs. In addition to pass or translate the
information from outside to DRAM controller, arbiter is also
responsible for which master has higher priority to access DRAMs. The
arbiter treats different DRAM access request as DRAM master, and that
makes there be 5 masters which are trying to access DRAMs by sending
their request to the arbiter. After one of them get the grant from the
arbiter, it owns DRAM bus and begins to do memory data transaction.
The masters are: CPU read request, PCI master, Posted write FIFO write
request, and Refresh request. The order of these masters shown above
also stands for their priority to access memory.
3.6 Refresh cycle
The refresh cycle will occur every 15.6 us. It is timed by a counter
of 14Mhz input. The CAS[7:0]# will be asserted at the same time, and
the RAS[5:0]# are asserted sequentially.
3.7 PCI bridge
SiS5571 is able to operate at both asynchronous and synchronous PCI
clocks. Synchronous mode is provided for those synchronous system to
improve the overall system performance. While in the PCI master write
cycles, post-write is always performed. And function of Write Merge
with CPU-to-DRAM post-write buffer is incorporated to eliminate the
penalty of snooping write-back. On the other hand, prefetch is enabled
for master read cycles by default, and such function could be disabled
optionally. And, Direct-Read from CPU-to-DRAM post-write buffer is
implemented to eliminate the overhead of snooping write-back also. In
addition to Write-Merge and Direct-Read, Snoop-Ahead also hides the
overhead of inquiry cycles for master to main memory cycles. These key
functions, Write-Merge, Direct-Read and Snoop-Ahead, achieve the
purpose of zero wait for PCI burst transfer. The post-write and
prefetch buffers are both 16 Double-Word deep FIFOs.
3.8 Snooping Control [omitted see datasheet]
3.9 AHOLD/BOFF# Process and Arbiter Interface [omitted see datasheet]
3.10 Target Initiated Termination [omitted see datasheet]
3.11 DATA Flow [omitted see datasheet]
3.12 PCI Master Read/Write DRAM Cycle [omitted see datasheet]
***Configurations:...
***Features:...
**5581/5582 (Jessie) Pentium PCI/ISA Chipset (75MHz) <04/15/97...
**5591/5592/5595 (David) Pentium PCI A.G.P. Chipset <01/09/98...
**5596/5513 (Genesis) Pentium PCI Chipset <03/26/96...
**5597/5598 (Jedi) Pentium PCI/ISA Chipset <04/15/97...
**530/5595 (Sinbad) Host, PCI, 3D Graphics & Mem. Ctrl.<11/10/98...
**540 (Spartan) Super7 2D/3D Ultra-AGP Single C.S.<11/30/99...
**55x SoC (System-on-chip) <03/14/02...
**
**Support chips:
**85C206 Integrated Peripheral Controller [no datasheet] ?...
**5595 Pentium PCI System I/O <12/24/97...
**950 LPC I/O <07/16/99...
**Other:...
**PII/III/Pro...
**Athlon etc...
*Symphony...
*TI (Texas Instruments)...
*UMC...
*Unresearched:...
*VIA...
*VLSI...
*Western Digital...
**WD7855 System controller for 80386SX <09/25/92
***Notes:...
***Info:
1.3 GENERAL DESCRIPTION
Western Digital's WD7855/LV single chip ISA System Controller is
designed for high-performance IBM PC/AT compatible platforms.
Available for desktop, portable or low voltage (LV) applications, the
WD7855/LV supports the 803868X microprocessor operating at speeds up
to 33 MHz.
The WD7855/LV incorporates seven high-performance system controller
functions which include the ISA bus interface, CPU interface, flexible
memory controller, DMA controller, interrupt controller, timers and
advanced power management. In combination with Western Digital’s
support devices, the WD7855/LV provides a highly flexible and powerful
desktop or portable platform design.
The WD7855/LV is designed to work with all variations of 80386SX
compatible microprocessors. It supports the traditional dynamic CPUs
with the industry's only Processor Power-down feature to minimize
power consumption. The WD7855/LV fully supports static microprocessors
such as the AMD Am386SXL with CPU Stop Clock, System Management
Interrupt and I/O trapping features. The WD7855/LV incorporates
special circuitry which allows for optimizing the cache performance
and maintaining cache coherency with cached CPUs such as the Cyrix
Cx4868LC.
1.3.1 Desktop Applications
The WD7855 provides a high performance solution with a flexible memory
controller architecture, including support for eight banks of two way
interleave memory and EMS 4.0 hardware. The WD7855/LV can fully
support an external look-aside cache or a combination primary and
secondary cache. This feature makes it particularly suitable for use
with cached microprocessors such as Cyrix Cx486SLC where it maintains
cache coherency via its built-in bus snooping capability. In addition,
the WD7855/LV supports Video Local Bus Interface (VLBI) for enhanced
graphics performance.
1.3.2 Portable Applications
The WD7855LV is an ideal choice because of its advanced power
management features and power saving 3.3 volt operation which delivers
long battery life in a compact footprint. This makes it a perfect
choice for laptop, notebook, pen based and palmtop computers.
The eight bank memory controller on the WD7855LV provides the user
with great flexibility in the selection of 3.3 volt DRAMs to meet
system memory requirements in low voltage platforms. The WD7855LV
memory controller supports JEDEC standard 3.3 volt DRAM in various
configurations, including the JEIDA standard 88-pin DRAM card.
The WD7855/LV can be paired with the appropriate support devices from
Western Digital to deliver the most efficient solution for any
platform. For 5 volt desktop or portable platforms, the WD7855LV can
be used with the WD76C20 Peripheral Controller and the WD76C30 I/O
Controller. Alternatively, the WD7855 can be used with the WD7615
Buffer Manager device and a generic Super I/O chip to implement a low
cost desktop platform. For 3.3 volt applications, the WD7855LV can be
used with the WD76C20ALV and WD76C30ALV, both of which incorporate
level translators (split rail operation). For subnotebook and palmtop
type applications, WD7625LV buffer manager can be added to the
WD7855LV based solution to achieve a very compact footprint.
The WD7855/LV is a fourth generation system controller device derived
from core chips with proven compatibility and design maturity in
several of the industry’s leading desktop and portable platforms.
Designed with the state of the art 0.9 micron high performance CMOS
process, the WD7855/LV family maintains architectural compatibility
with Western Digital's WD7600 and WD7700 systems logic chip sets while
incorporating many additional performance enhancements.
***Configurations:...
***Features:...
**WD7900/LP/LV System Chip Set for 80286 or 80386SX (Cache) <11/25/91...
**WD8110 System controller for 80386DX/486 <11/30/93...
**
**Support Chips:
**WD76C20x Floppy, RTC, IDE and Support Logic Device <11/25/91...
**WD76C30x Perip. Ctrl, Interrupt Multiplex, and Clock Gen <11/18/91...
**WD7615 Desktop Buffer Manager <04/15/92...
**WD7625 Desktop Buffer Manager <10/01/92...
**WD8120LV Super I/O [no datasheet] ?
**Other Chips:...
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