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**ET6000     "Cheetah" 486DX/SX Non-Cache System                <Apr92
***Info:...
***Configurations:...
***Features:...
**ET9000     "Jaguar" 486 Write Back Cache AT Single Chip       <Jun92...
**ET9800/391 "Firefox" 386SX Write Back chipset [no datasheet]       ?...
**82C390SX   "Panda" S.C. 386SX Direct Mapped Cache [no d.sheet]cFeb92...
**66x8       VIA clones [no datasheet]                               ?...
*Faraday...
*Forex . . . . . . [List only, no datasheets found]...
*Intel...
**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...
**800 series...
*Headland/G2...
*HMC (Hulon Microelectronics)...
*Logicstar...
**SL6012  Memory Mapper for PC-AT (74LS612 compatible)          <Jul87
***Info:
The SL6012 Memory  Mapper is intended for use in  PC-AT design. It can
expand an address bus by 4  bits. In PC-AT applications, 4 bits of the
source  address   are  used  to  select   1  of  16,   eight  bit  map
registers. These registers  are normally programmed (through software)
with the  starting address of each  memory page. The  register data is
output directly for  use as the most significant  bits of the expanded
address bus. The 8 bits from the SL6012 are used along with the unused
source address bits to form the expanded address bus.

As shown  in Table 1  [see datasheet], the  SL6012 has three  modes of
operation; read, write and map. Data may be written into, or read from
the Memory  Mapper when  chip select CSN  is low. The  register select
inputs (RS0 through RS3) select one of the sixteen map registers. When
RWN is  low, data is written  into a register from  the data bus. When
RWN is high  data is output from a Memory Mapper  register to the data
bus.

The map mode of operation is selected when chip select CSN is high. In
this mode, the  register data selected by the  map address inputs (MA0
through  MA3)  will be  available  on  the  map outputs  (MO0  through
MO7).  Note that  the map  registers are  addressed by  either  the RS
inputs or  the MA inputs depending  upon the operating  mode. When MEN
(Map Enable) is low the map  outputs (MO0-MO7) are active. When MEN is
high, the map outputs are at high impedance.

***Versions:...
***Features:...
**SL9010  System Controller (80286/80386SX/DX, 16/20/25MHz)     <oct88...
**SL9020  Data Controller                                       <oct88...
**SL9025  Address Controller                                    <oct88...
**SL9090  Universal PC/AT Clock Chip                            <oct88...
**SL9250  Page Mode Memory Controller (16/20MHz 8MB Max)        <oct88...
**SL9350  Page Mode Memory Controller (16/20/25MHz 16MB Max)    <oct88...
**Other:...
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*Unresearched:...
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*ZyMOS...
*General Sources:...

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