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**82485       Turbo Cache (and 485Turbocache)                      c90
***Notes:...
***Info:
The 82485 is  a second-level cache controller designed  to improve the
performance  of  Intel486  Microprocessor  systems.  One  82485  cache
controller supports  64K or  128K bytes of  second level  cache memory
that maps  to the  entire 4 Gigabytes  of the  Intel486 microprocessor
address space. The controller  is completely software transparent. One
controller plus SRAMs  provides a 64K or a  128K cache. External EPROM
can  be  cached  yet  remain  write protected.   The  82485  is  fully
compatible  with the  Intel486  microprocessor. All  Intel486 CPU  bus
cycles and timings are supported.

A complete, optional second level  cache controller using the 82485 is
available  as the 485Turbocache  Module from  Intel (data  sheet order
number 240722).

2.0 FUNCTIONAL DESCRIPTION
2.1 Introduction
The 82485 is a single ported, two-way set associative cache controller
designed specifically  to interface with  the Intel486 microprocessor.
The controller supports either a sectored configuration (two lines per
tag) or  a non-sectored configuration  (one line per tag).   The 82485
will directly support a nonsectored  64K data cache or a 128K sectored
data cache.  Both the 64K and  128K configurations are able to map the
entire 4 gigabytes of  the Intel486 microprocessor address space.  The
82485 interfaces directly to  the Intel486 microprocessor.  All Intel-
486 CPU bus cycles and timings are supported.  The 82485 also supports
0 wait  state processor operation  when there is  a cache hit  and has
provisions to support invalidation cycles, BOFF# cycles, and premature
BLAST# terminations.  The controller  is look aside (monitors bus act-
ivity in parallel to the processor) and write through (all writes pro-
pagate to the  system bus), so it supports  the same cache consistency
mechanisms as the  Intel486 CPU.  The controller also  provides a safe
method to cache ROM BIOS through the  use of a write protect pin and a
write protect strapping option.

The data cache  (Static RAM) resides external to  the 82485. The 82485
provides all  controls for  the SRAMs.  No  external latches  or tran-
ceivers are  required.  The 82485  output buffers support up  to eight
SRAMs.  A  64K cache can be  designed with only  five components; nine
components for a 128K cache.  Two-way set associativity is provided by
dual banked SRAMs. Data parity is supported.

The  82485  can  be  used  to  design  a  custom  second  level  cache
configuration. For an easier system design and higher integration, the
82485M Turbocache  can be used  (see data sheet order  number 240722).
This  module is  a  complete second  level  cache in  one package.  It
consists  of a single  82485 cache  controller and  SRAM to  provide a
complete 64K or 128K second level Intel486 microprocessor second level
cache.

***Versions:...
***Features:...
**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
Chips:         
Memory Access Controller (MAC)  
Data Interface Buffer (DIB)
CPUs:          8x P-III Xeon Oct
DRAM Types:    SDRAM PC100 2-way Interleave dual channel
Max Mem:       32GB
ECC/Parity:    ECC
AGP speed:     N/A
Bus Speed:     100
PCI Clock/Bus: 1/3 PCI-66/64



**800 series...
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*OPTi...
*PC CHIPS/Amptron/Atrend/ECS/Elpina/etc...
*SIS...
*Symphony...
**SL82C470   'Mozart' 486/386 EISA chipset                     c:Dec91
***Info:...
***Configurations:...
***Features:
o   100% EISA compatible
o   20/25/33/50 MHz 80486 DX/SX CPU operation
o   25/33/40 Mhz 80386DX CPU Operation
o   Integrated write back cache controller with built-in tag comparator
o   Concurrent CPU-cache and EMA/master operations with bus snooping
o   Only ten TTL components are required
o   Complete EISA system can be built on a baby AT sized motherboard
o   Flexible cache size from 64KB to 1MB
o   Page mode DRAM operation supporting 1 to 4 banks up to 256MB
o   Video/system BIOS, shadowing and caching
o   Supports both conventional and concurrent configurations
o   Inclusive secondary cache for snoop filtering
o   Synchronous EISA bus clock
o   Transparent Gate A20 and CPU reset
o   CPU local bus device support
o   Supports 80387, 80487SX and Weitek 3167/4167 co-processors
o   Decoupled refresh without holding CPU
o   Staggered DRAM refresh to minimize power supply noise
o   Rlch set of register options to allow customization
o   Three 160-pin PQFP packages in low power and high speed 0.8um CMOS 
    Technology
**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...
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*Western Digital...
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*General Sources:...

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