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486SX/DX/DX2-MAINBOARD
UNIDENTIFIED
486SX/DX/DX2-MAINBOARD
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Processor
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80486SX/80486DX/80486DX2
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Processor Speed
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20/25/33/50(internal)/50/66(internal)MHz
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Chip Set
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UNI
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Video Chip Set
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None
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Maximum Onboard Memory
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32MB
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Maximum Video Memory
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None
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Cache
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64/128/256KB
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BIOS
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AMI
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Dimensions
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260mm x 220mm
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I/O Options
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32-bit VESA local bus slots (3)
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NPU Options
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None
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CONNECTIONS
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Purpose
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Location
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Purpose
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Location
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Turbo switch
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H1
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Reset switch
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H5
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Turbo LED
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H2
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External battery
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J1
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Power LED & keylock
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H3
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32-bit VESA local bus slots
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SL1 - SL3
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Speaker
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H4
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USER CONFIGURABLE SETTINGS
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Function
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Label
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Position
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»
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Turbo enabled
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H1
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Closed
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Turbo enabled through keyboard (CTRL, ALT, +)
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H1
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Open
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Turbo disabled through keyboard (CTRL, ALT, -)
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H1
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Open
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»
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CMOS memory normal operation
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J1
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Pins 2 & 3 closed
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CMOS memory clear
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J1
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Pins 3 & 4 closed
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Battery type select external
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J1
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Closed
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»
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Monitor type select color
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J3
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Closed
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Monitor type select monochrome
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J3
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Open
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»
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VL-BUS clock normal operation
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JP43
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Pins 2 & 3 closed
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VL-BUS clock adjusted
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JP43
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Pins 1 & 2 closed
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DRAM CONFIGURATION
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Size
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Bank 0
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Bank 1
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1MB
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(4) 256K x 9
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None
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2MB
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(4) 256K x 9
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(4) 256K x 9
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4MB
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(4) 1M x 9
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None
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5MB
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(4) 256K x 9
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(4) 1M x 9
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8MB
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(4) 1M x 9
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(4) 1M x 9
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16MB
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(4) 4M x 9
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None
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20MB
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(4) 1M x 9
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(4) 4M x 9
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20MB
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(4) 4M x 9
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(4) 1M x 9
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32MB
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(4) 4M x 9
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(4) 4M x 9
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CACHE CONFIGURATION
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Size
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Bank 0
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Bank 1
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TAG
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64KB
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(4) 8K x 8
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(4) 8K x 8
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(1) 8K x 8
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128KB
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(4) 32K x 8
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None
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(1) 8K x 8
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256KB
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(4) 32K x 8
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(4) 32K x 8
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(1) 32K x 8
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CACHE JUMPER CONFIGURATION
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Size
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JP6
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JP7
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JP8
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JP9
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64KB
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Open
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Closed
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Open
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Pins 1 & 2 closed
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128KB
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Open
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Closed
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Closed
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Pins 1 & 2, 3 & 4 closed
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256KB
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Closed
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Closed
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Closed
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Pins 1 & 2, 4 & 5 closed
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CPU SPEED SELECTION
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Speed
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JP29
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JP30
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JP31
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20MHz
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Open
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Closed
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Open
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25MHz
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Closed
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Open
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Closed
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33MHz
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Closed
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Closed
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Open
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50iMHz
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Closed
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Open
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Closed
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50MHz
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Open
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Closed
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Open
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66iMHz
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Closed
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Closed
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Open
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CPU TYPE SELECTION
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Type
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JP4
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80486SX
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Pins 5 & 6 closed
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80486DX
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Pins 1 & 2, 4 & 5, 6 & 7 closed
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80486DX2
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Pins 1 & 2, 4 & 5, 6 & 7 closed
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VL BUS WAIT STATE SELECTION
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Setting
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JP20
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0
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Open
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1
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Closed
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VL BUS SPEED SELECTION
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Speed
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JP19
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<= 33MHz
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Open
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>33 MHz
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Closed
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