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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...
**800 series...
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SL7001 MDA Graphics Controller
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**82C895 System/Power Management Controller (cached) c:Sep94
***Notes:...
***Info:...
***Configurations:...
***Features:
o Processor interface:
- Intel 80486SX, DX, DX2, SLe, DX4, P24T, P24D
- AMD 486DX, DX2, DXL, DXL2, Plus
- Cyrix DX, DX2, M7
- CPU frequencies supported 20, 25, 33, 40 and 50MHz
o Cache interface:
- Direct Mapped Cache
- Two banks interleaved or single bank non-interleaved
- 64, 128, 256 and 512K cache sizes
- Programmable wait states for L2 cache reads and writes
- 2-1-1-1 read burst and zero wait state write @ 33MHz
- No Valid bit required
- Supports CPUs with L1 write-back support
o DRAM interface:
- Up to 128MB main memory support
- Supports 256KB, 1MB, 4MB, and 16MB single- and double-sided SIMM
modules
- Read page-hit timing of 3-2-2-2 at 33MHz
- Supports hidden, slow and CAS-before-RAS refresh
- Four RAS lines to support four banks of DRAM
- Programmable wait states for DRAM reads and writes
- Enhanced DRAM configuration map
o Power management:
- Support for SMM (System Management Mode) for system power
management implementations
- Programmable power management
- Programmable wake-up events through hardware, software and
external SMI source
- Multiple level GREEN support (NESTED_GREEN)
- STPCLK# protocol support
- One programmable GREEN event timer
o ISA interface:
- 100% IBM PC/AT ISA compatible
- Integrates DMA, timer and interrupt controllers
- Optional PS/2 style IRQ1 and 12 latching
o VESA VL interface:
- Conforms to the VESA v2.0 specification
- Optional support for up to two VL masters
o Miscellaneous features:
- Full support for shadow RAM, write protection, L1/L2
cacheability for video, adapter and system BIOS
- Enhanced arbitration scheme
- Transparent 8042 emulation for fast CPU reset and GATEA20
generation
o Packaging:
- Higher integration
- Reduced TTL count
- Low-power, high-speed 0.8-micron CMOS technology
- 208-pin PQFP (Plastic Quad Flat Pack)
**82C898 System/Power Management Controller (non-cache)c:Nov94...
**
**Support Chips:
**82C601/2 Buffer Devices <Nov94...
**82C822 PCIB (VLB-to-PCI bridge) c:94...
**Other:...
*PC CHIPS/Amptron/Atrend/ECS/Elpina/etc...
*SIS...
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