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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...
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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:
The SL82C470 chip set provides  a very high performance.  highly inte-
grated and cost-effective implementation for personal computer systems
based on the  standard EISA bus.  It supports  both 386DX and 486DX/SX
CPUs over the entire performance range, from 20Mhz to 50Mhz.  The chip
set  can  operate in  either  "conventional"  or "concurrent"  config-
uration.  Under the conventional configuration, the cache subsystem is
dedicated to bus snooping when  a DMA or master device becomes active.
Under the concurrent  configuration, the CPU-cache operation continues
while  bus snooping  is  performed for  the  DMA or  master device  to
explore maximum  concurrency between the  CPU and the EISA  bus.  Only
ten  TTLs are  required for  a complete  motherboard design  under the
conventional  configuration in  addition to  the chip  set  and memory
devices.  Five  additional  TTLs   are  required  for  the  concurrent
configuration.  A complete EISA  system of either configuration can be
easily implemented on a baby AT sized motherboard.

The  SL82C470 chip  set consists  of three  160-pin PQFP  devices: the
SL82C471  integrated  cache/DRAM  controller,  the SL82C472  EISA  bus
controller and the SL82C473 DMA controller.

SL820471 Cache/DRAM Controller

The  SL82C47l  Cache/DRAM  controller  controls  the  cache  and  DRAM
accesses from  the CPU,  EISA/ISA masters and  DMA devices.   The chip
adapts a write-back cache  scheme to minimize the interference between
the CPU-cache and DMA/master  during their concurrent operations.  The
cache  size ranges from  64KB to  1MB with  advanced features  such as
2-1-1-1  burst  line fill.   Snoop-filtering,  local  bus support  and
programmable non-cacheable and  write-protected regions. The page mode
DRAM controller supports 1 to 4 banks of DRAMS up to 256MB.  A mixture
of 256KB, 1MB.  4MB and 16MB DRAMs is supported.  The video and system
BIOS  can  be  shadowed   or  cached  independently.   The  cache-DRAM
subsystem allows zero wait state burst mode DMA transfers to take full
advantage of the high bandwidth of the EISA bus.

The DRAM  data bus can either  be connected directly to  the CPU local
bus or  be buffered externally,  The control signals for  the external
buffers are generated by the SL82C471.

SL82C472 EISA Bus Controller

The  SL82C472  EISA  bus  controller translates  bus  control  signals
between the  CPU, EISA/ISA and DMA  masters and slaves.  The chip also
includes buffers  and byte/word swap  logic between the CPU  (or DRAM)
and the EISA bus. The  bus conversion and data alignment are performed
automatically.

The  SL82C472 includes two  8259 interrupt  controllers and  four 8254
timer channels  modified for 100%  EISA compatibility.  The  chip also
includes parity generation and check logic and NMI and timeout logic.

SL82C473 EISA DMA Controller

The SL82C473  DMA controller implements  seven EISA DMA  channels. the
system arbiter and the co-processor interface logic.  The DMA control-
ler  supports compatible  type  A,  type B  and  type  C (burst)  mode
operations  with  the  buffer  chaining  capability.   The  multilevel
rotating priority  arbitration with  fail-safe timeout  is implemented
for the  system arbiter.  Six  sets of slot-specific  master handshake
signals (MACK  and MREQ)  are provided  directly without  any external
components.

The address latches and buffers for  the EISA bus are also included in
the SL82C473.

***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...
*VLSI...
*Western Digital...
**FE6500        CPU Core Logic for PS/2 Model 70/80 Compatibles   c:88
***Notes:...
***Info:...
***Configurations:...
***Features:...
**WD6400SX/LP   CPU Core Logic for PS/2 386SX Compatibles          <90...
**WD6500        CPU Core Logic for PS/2 386DX/486 Compatible       <90...
**WD7600A/LP/LV System Chip Set for 80286 or 80386SX         <11/25/91...
**WD7700/LP     System Chip Set for 80286 or 80386SX (Cache) <11/25/91...
**WD7855        System controller for 80386SX                <09/25/92...
**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:...
*Winbond...
*ZyMOS...
*General Sources:...

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