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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:...
**450NX  (?)            06/29/98:...
**?????  (Profusion)    c:99...
**800 series...
*Headland/G2...
*HMC (Hulon Microelectronics)...
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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...
**SL82C470   'Mozart' 486/386 EISA chipset                     c:Dec91
***Info:...
***Configurations:...
***Features:...
**SL82C490   'Wagner' 486?              [no datasheet]               ?...
**SL82C550   'Rossini' Pentium          [no datasheet]            c:95...
**
**Support Chips:
**SL82C365    Cache Controller (for 386DX/SX)                     c:91...
**SL82C465    Cache Controller (for 486/386DX/SX)                 c:91...
*TI (Texas Instruments)...
*UMC...
*Unresearched:...
*VIA...
**VT82C597/AT  Apollo VP3, Single-Chip for Pentium with AGP  <10/03/97
***Info:...
***Configurations:...
***Features:
o   PCI/ISA Green PC Ready
    - Supports separately powered 3.3V (5V tolerant) interfaces to 
      system memory, AGP, and PCI bus
    - Supports 3.3V and sub-3.3V interface to CPU
    - PC-97 compatible using VT82C586B South Bridge with ACPI Power 
      Management
o   High Integration
    - Single chip implementation for 64-bit Socket-7-CPU, 64-bit 
      system memory, 32-bit PCI and 32-bit AGP interfaces
    - Apollo VP3  Chipset: VT82C597 or VT82C597AT  system controller 
      and VT82C586B  PCI to ISA bridge
    - Chipset includes UltraDMA-33 EIDE, USB, and Keyboard / PS2-Mouse 
      Interfaces plus RTC / CMOS on chip
o   Flexible CPU Interface
    - Supports 64-bit Pentium, AMD 5k86, AMD 6k86 and Cyrix 6x86 CPUs
    - CPU external bus speed up to 66 MHz (internal 233MHz and above)
    - Supports CPU internal write-back cache
    - System management interrupt, memory remap and STPCLK mechanism
    - Cyrix 6x86 linear burst support
    - CPU NA# / Address pipeline capability
    - 4 cache lines of CPU/cache-to-DRAM post-write buffers
    - 4 quadwords of CPU/cache-to-DRAM read-prefetch buffers
o   Advanced Cache Controller
    - Direct map write back or write through secondary cache
    - Pipelined burst synchronous SRAM (PBSRAM) cache support (with 
      global write enable feature)
    - Flexible cache size: 0K / 256K / 512K / 1M / 2MB
    - 32 byte line size to match the primary cache
    - Integrated 10-bit tag comparator
    - 3-1-1-1 read/write timing for PBSRAM access at 66 MHz
    - 3-1-1-1-1-1-1-1 back to back read timing for PBSRAM access at 
      66 MHz
    - Sustained 3 cycle write access for PBSRAM access or CPU to DRAM 
      and PCI bus post write buffers at 66 MHz
    - Data streaming for simultaneous primary and secondary cache line 
      fill
    - System and video BIOS cacheable and write-protect
    - Programmable cacheable region and cache timing
o   AGP Controller
    - AGP v1.0 compliant
    - Supports SideBand Addressing (SBA) mode (non-multiplexed 
      address/data)
    - Supports 133MHz 2X mode for AD and SBA signalling
    - Pipelined split-transaction long-burst transfers up to 533 MB/
      sec
    - Eight level read request queue
    - Four level posted-write request queue
    - Thirty-two level (quadwords) read data FIFO (128 bytes)
    - Sixteen level (quadwords) write data FIFO (64 bytes)
    - Intelligent request reordering for maximum AGP bus utilization
    - Supports Flush/Fence commands
o   GART
    - One level TLB structure
    - Sixteen entry fully associative page table
    - LRU replacement scheme
    - Independent GART lookup control for host / AGP / PCI master 
      accesses
o   Intelligent PCI Bus Controller
    - PCI buses are synchronous to host CPU bus
    - 33 MHz operation on the primary PCI bus
    - 66 MHz PCI operation on the AGP bus
    - PCI-to-PCI bridge configuration on the 66MHz PCI bus
    - Separate data buffers for the two PCI buses
    - Peer concurrency
    - Concurrent multiple PCI master transactions;  i.e., allow PCI 
      masters from both PCI buses active at the same time
    - Allows PCI master access while ISA master/DMA is active
    - PCI master snoop ahead and snoop filtering
    - Five levels (double-words) of CPU to PCI posted write buffers
    - Byte merging in the write buffers to reduce the number of PCI 
      cycles and to create further PCI bursting possibilities
    - Zero wait state PCI master and slave burst transfer rate
    - PCI to system memory data streaming up to 132Mbyte/sec
    - Enhanced PCI command optimization (MRL, MRM, MWI, etc.)
    - Forty-eight levels (double-words) of post write buffers from PCI 
      masters to DRAM
    - Sixteen levels (double-words) of prefetch buffers from DRAM for 
      access by PCI masters
    - Supports L1/L2 write-back forward to PCI master read to minimize 
      PCI read latency
    - Supports L1/L2 write-back merged with PCI master post-write to 
      minimize DRAM utilization
    - Transaction timer for fair arbitration between PCI masters 
      (granularity of two PCI clocks)
    - Symmetric arbitration between Host/PCI bus for optimized system 
      performance
    - Complete steerable PCI interrupts
    - PCI-2.1 compliant, 32 bit 3.3V PCI interface with 5V tolerant 
      inputs
o   Advanced High-Performance DRAM Controller
    - 66MHz DRAM interface
    - Concurrent CPU and AGP access
    - FP, EDO, SDRAM, and SDRAM-II
    - 66MHz DDR (Double Data Rate) supported for SDRAM-II
      (supports central and edge DQ, bidirectional DS, and optional 
      SDR write)
    - Different DRAM types may be used in mixed combinations
    - Different DRAM timing for each bank
    - Mixed 1M / 2M / 4M / 8M / 16MxN DRAMs
    - 6 banks up to 1GB DRAMs
    - Flexible row and column addresses
    - 64-bit data width only
    - 3.3V DRAM interface with 5V-tolerant inputs
    - Optional bank-by-bank ECC (single-bit error correction and 
      multi-bit error detection) or EC (error checking only) for DRAM 
      integrity
    - Two-bank interleaving for 16Mbit SDRAM support
    - Two-bank and four bank interleaving for 64Mbit SDRAM support 
      (14 MA lines)
    - Supports maximum 8-bank interleave (i.e., 8 pages open 
      simultaneously);  banks are allocated based on LRU
    - Seamless DRAM command scheduling for maximum DRAM bus utilization
      (e.g., precharge other banks while accessing the current bank)
    - Four cache lines (16 quadwords) of CPU/cache to DRAM write 
      buffers
    - Concurrent DRAM writeback
    - Read around write capability for non-stalled CPU read
    - Burst read and write operation
    - 5-2-2-2 on page, 8-2-2-2 start page and 11-2-2-2 off page timing 
      for EDO DRAMs at 66 MHz
    - 6-1-1-1 on page, 8-1-1-1 start page and 10-1-1-1 off page for 
      SDRAMs at 66 MHz
    - 5-2-2-2-3-2-2-2 back-to-back accesses for EDO DRAM at 66 MHz
    - 6-1-1-1-3-1-1-1 back-to-back accesses for SDRAM at 66 MHz
    - BIOS shadow at 16KB increment
    - Decoupled and burst DRAM refresh with staggered RAS timing
    - Programmable refresh rate, CAS-before-RAS refresh and refresh on 
      populated banks only
o   Built-in NAND-tree pin scan test capability
o   3.3V, 0.5um, high speed / low power CMOS process
o   472 pin BGA Package
o   Alternate pinouts available to optimally accommodate different PCB 
    form factors
    - VT82C597 for ATX and NLX
    - VT82C597AT for Baby AT and ATX

**VT82C598MVP  Apollo MVP3,Single-Chip 66/75/83/100MHz & AGP <09/22/97...
**VT8501       Apollo MVP4,Single-Chip 66-100MHz & AGP       <11/04/98...
**VT82C680     Apollo P6, Pentium-Pro Chip Set               <08/30/96...
**Support chips:
**VT82C505     Pentium/486 VL to PCI Bridge                  <05/30/94...
**VT82C586/A/B PCI Integrated Peripheral Controller          <10/13/96...
**VT82C596/A   Mobile PCI Integrated Peripheral Controller   <11/05/97...
**VT82C686A/B  PCI Super-I/O Integrated Peripheral Ctrl.     <02/10/98...
**Later P-Pro/II/III/Celeron...
**Later AMD...
**Other...
*VLSI...
*Western Digital...
*Winbond...
*ZyMOS...
*General Sources:...

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