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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...
*Headland/G2...
*HMC (Hulon Microelectronics)...
*Logicstar...
*Motorola...
*OPTi...
**82C291 SXWB PC/AT Chipset (386SX) c:91
***Info:...
***Configurations:...
***Features:...
**82C295 SLCWB PC/AT Chipset (386SX) ?...
**82C381/382 HiD/386 (386DX) c:89...
**82C391/392 386WB PC/AT Chipset (386DX) <Dec90...
**82C461/462 Notebook PC/AT chipset [no datasheet] ?...
**82c463 SCNB Single Ship Notebook c:92...
**82c465MV/A/B Single-Chip Mixed Voltage Notebook Solution <Oct97...
**82C481?/482? HiP/486 & HiB/486 [no datasheet] Oct89...
**82C491/392 486WB PC/AT Chipset <04/21/91...
**82C493/392 486SXWB <10/21/91...
**82C495SX/392SX LCWB PC/AT chipset [no datasheet] ?...
**82C495SLC DXSLC 386/486 Low Cost Write Back c:92...
**82C495XLC PC/AT Chip Set c:93...
**82c496A/B DXBB PC/AT Chipset <Mar92...
**82C496/7 DXBB PC/AT Chipset (Cached) <01/16/92...
**82C498 DXWB PC/AT chipset [no datasheet] ?...
**82C499 DXSC DX System Controller c:93...
**82C546/547 Python PTM3V c:94...
**82C556/7/8 Viper [no datasheet] ?...
**82C556/7/8N Viper-N Viper Notebook Chipset <05/25/95...
**82C556M/7M/8E Viper-N+ Viper Notebook Chipset c:96...
**82C566/7/8 Viper-Max Chipset Scalable MultiMedia PC Solution ?...
**82C571/572 486/Pentium c:93...
**82C576/7/8 Viper Xpress [no datasheet] ?...
**82C576/8/9 Viper XPress+ [no datasheet, some info] <01/16/97...
**82C596/597 PTMAWB Pentium Adaptive Write-back (Cobra) c:93...
**82C650/1/2 Discovery (Pentium Pro) [no datasheet] ?...
**82C681/2/6/7 386/486WB EISA c:92...
**82C683 386/486AWB EISA [no datasheet] ?...
**82C693/6/7 Pentium uP Write Back Cache EISA c:93...
**82C700 FireStar c:97
***Info:...
***Configurations:...
***Features:
PCI Bus
o PCI supports sustained X-1-1-1 bursts, even to DRAM through an
innovative mechanism. PCI operation can be concurrent with
CPU/L2 cache and IDE operations.
o PCI clock generation eliminates the need for external PCI clock
buffers in many designs and allows the PCI bus to be effectively
power-managed.
o 3.3V or 5.0V PCI is supported on the FireStar PCI bus. If FireStar
is configured for 3.3V operation, 5.0V-only PCI plug-in cards and
docking stations can still be supported through a bridge device
such as OPTi's 820824 Cardbus Controller/Docking Solution, whose
prefetch and post-write buffers off-load operations from the
primary PCI bus.
DRAM Controller
o Provides BIOS with the means to automatically detect the DRAM type
in use on each bank, whether fast page mode, EDO, or synchronous
DRAM, allowing BIOS routines to efficiently program DRAM
operation.
ISA Bus
o A full ISA bus is directly provided to support the keyboard
controller, BIOS ROM, and Compact ISA peripheral devices for local
ISA support with no TTL. When reduced ISA operation is selected,
other FireStar pins become available for general purpose use.
Bus Mastering IDE
o FireStar supports two bus mastering IDE channels that function
concurrently with operations on the CPU/L2 cache interface and PCI
interface. Up to four drives are supported.
o An emulated bus mastering IDE feature allows IDE drives that are
not commonly available as bus mastering devices, such as CD-ROM
drives, to act as bus mastering drives. For example, a CD-ROM
drive can transfer video data to DRAM while the CPU is
decompressing the data and sending it to the graphics controller.
Thermal Management
o Fail-safe thermal management incorporates feedback logic that
requires a very inexpensive external sensor circuit.
o Hardware monitors temperature directly and reliably, while the
fail-safe aspect of the circuitry ensures that sensor component
failure will automatically inhibit CPU clocking to prevent
overheating.
o SMM code will be able to read (and display if desired) actual CPU
temperature.
ACPI Implementation
o Microsoft Advanced Configuration and Power Interface (ACPI) is
being implemented in the FireStar silicon. ACPI is a standard
register interface for power management function jointly developed
by Microsoft, Intel, and Toshiba.
Miscellaneous
o The standard version of the chip can run at 3.3V, up to 66MHz on
the CPU bus.
o A new Context Save Mode feature allows chip registers to be saved
and restored more efficiently than ever before, requiring less SMM
code and storage space.
o The OPTi Viper-N+ Power Management Unit is used, maintaining
backward compatibility down to the register level with previously
written support firmware.
o Serial IRQs are supported as an option for interrupts on PCI.
o Known devices in the system can be positively decoded on the PCI
bus, eliminating the delay for subtractive decode and improving
the efficiency of ISA operations.
o ISA bus cycle speed can be individually controlled to certain ISA
device groups.
o Simple logic gate functions can be assigned to unused pins to
eliminate the need for external TTL. Pin programming is far more
flexible than ever possible on any other chip.
**82C701 FireStar Plus c:97...
**82C750 Vendetta [no datasheet] ?...
**82c801 SCWB2 DX Single Chip Solution c:92...
**82C802 SCWB2 PC/AT Single Chip [no datasheet] ?...
**82C802G/GP System/Power Management Controller (cached) c:93...
**82C895 System/Power Management Controller (cached) c:Sep94...
**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...
*Symphony...
*TI (Texas Instruments)...
*UMC...
*Unresearched:...
*VIA...
*VLSI...
*Western Digital...
*Winbond...
*ZyMOS...
*General Sources:...
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