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**82495XP/490XP Cache Controller / Cache RAM (for i860) 06/05/91
***Notes:...
***Info:...
***Features:...
**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)...
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**82C281/282 Cache Sx/AT (386SX) <08/22/91
***Notes:...
***Info:...
***Configurations:...
***Features:
o Flexible DRAM Banks Configuration
- The 82C281/2 supports 256K, 1M, and 4M memory devices, total
main memory size can be up to 16MB. A total of 12 different
memory configurations are supported.
o Page Mode Operation
- Based on the memory configuration shown above [see datasheet],
the memory control unit inside the 820281/2 performs page mode
of operation with a varying block size of 1k, 2k, or 4k bytes
for 256k, 1M, or 4M DRAMs respectively.
o System BIOS Shadow RAM
- The 820281/2 memory control unit provides shadow RAM feature for
several areas of memory system BIOS, video BIOS, and adapter
BIOS.
o Memory Remapping
- If shadow RAM feature is not utilized for the memory area
between 0D0000H - 0EFFFFH, then memory remapping is possible.
The local DRAM areas, 0A0000H - 0BFFFFH and 0D0000H - 0EFFFFH, a
total of 256 KByte, are remapped to the top of total system
memory. The areas for 0F0000H-0FFFFFH (system BIOS) and
0C000H-0CFFFFH (Video BIOS) are reserved for shadow RAM purpose.
o Flexible Multiplexed DRAM Address
o Cache Control Subsystem
- Direct-mapped posted write cache control function provides a low
cost alternative to enhance the system performance by up to 50%.
In order to simplify the design without increasing the system
cost or decreasing performance, the 82C281/2 has been designed
to support only non-pipeline mode for systems with cache memory.
The 82C281/2 offers the following cache control features:
- Flexible Cache Memory Size
- 4MB Cacheabie main memory by using 16KB low cost SRAM.
- 8MB Cacheable main memory by using 32KB low cost SRAM.
- Cache 16MB main memory by using 64KB low cost SRAM.
- Increase the cache size beyond 64KB up to 512KB
- Cache Line Size 4 Byte
- Burst mode memory prefetch is supported by the 82C281/2.
During cache read miss cycles, the memory control subsystem
will perform two consecutive read cycles to fetch 4 bytes
from main memory before terminating the cycle by sending
RDYO# signal to 3868X.
- Non-Cacheable Area
The non-cacheable areas are predefined as indicated below:
- I/O address space
- memory address between 0A0000H and 0FFFFFH.
- any memory address beyond the current configured memory
size.
- programmable non-cacheable memory area as defined by
82C281/2 internal registers.
- 82C281 Posted Write Cache
- The 820281 supports flexible direct-mapped cache with posted
write through update of main memory. By programming the
internal register, the post write control signals are
provided by the 820281 to support a one level write buffer.
With posted write, the CPU write cycles can be completed in
2 CPU T-States, thereby increasing system performance.
- 820282 Write Through Cache
- The 820282 supports a write-through cache system which
allows the designer to reduce system cost by eliminating two
F244's and two F373‘s with only a slight reduction in system
performance (5-10%).
- AT Bus Control
- The 820281/2 AT bus control unit handles all of the AT bus
operations and the DMA/Refresh arbitration. The AT bus
control unit supports the following features:
- Programmable AT Bus Clock - The AT bus clock, ATCLK. can
be programmed as CLK2/6, which is default, or CLK2/4.
- Turbo Switch - The 820281/2 provides a turbo switch
feature that allows users to change the system clock
speed. A programmable bit will enable or disable this
turbo function. When the turbo function is enabled by
setting reg[14H], bit[1] to 1, the 82C281/2 turbo pin
then determines the system clock speed. A low on the
turbo pin forces the CPU to run at the current AT bus
speed which IS CLK2/6 or CLK2/4.
**82C283 386SX System Controller c:91...
**82C291 SXWB PC/AT Chipset (386SX) c:91...
**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:...
**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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