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425SX, 433SX, 433DX, 450DX2, 466DX2
TANDY/RADIO SHACK
425SX, 433SX, 433DX, 450DX2, 466DX2
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Processor
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80486SX/ODP486SX/80487SX/80486DX/ODP486SX/80486DX2
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Processor Speed
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25/33/50(internal)/66(internal)MHz
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Chip Set
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Unidentified
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Video Chip Set
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Unidentified
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Maximum Onboard Memory
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40MB
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Maximum Video Memory
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1MB
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Cache
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64/128/256KB
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BIOS
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Phoenix
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Dimensions
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330mm x 218mm
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I/O Options
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Floppy drive interface, IDE interface, parallel port, PS/2 mouse port, serial ports (2), VGA feature connector, VGA port, riser slot
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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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VGA port
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CN1
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External battery
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J7
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Parallel port
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CN2
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IDE interface
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J17
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Serial port 1
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CN3
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Floppy drive interface
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J18
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Serial port 2
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CN4
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VGA feature connector
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J21
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PS/2 mouse port
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CN5
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Riser slot
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SL1
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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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Factory configured - do not alter
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J9
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Pins 1 & 2 closed
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»
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Factory configured - do not alter
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J11
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Open
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»
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Factory configured - do not alter
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J13
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Pins 1 & 2 closed
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»
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Factory configured - do not alter
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J14
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Pins 2 & 3 closed
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»
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CMOS memory normal operation
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J20
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Closed
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CMOS memory clear
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J20
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Open
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»
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On board video enabled
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J28
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Pins 2 & 3 closed
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On board video disabled
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J28
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Pins 1 & 2 closed
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»
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Factory configured - do not alter
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J29
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Open
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»
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Floppy drive write protect disabled
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J30
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Pins 2 & 3 closed
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Floppy drive write protect enabled
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J30
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Pins 1 & 2 closed
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»
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Factory configured - do not alter
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J31
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Pins 2 & 3 closed
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»
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Zero wait state enabled
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J32
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Closed
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Zero wait state disabled
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J32
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Open
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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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Bank 2
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1MB
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(1) 256K x 36
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None
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None
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2MB
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None
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(4) 256K x 9
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(4) 256K x 9
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2MB
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(1) 512K x 36
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None
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None
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4MB
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None
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(4) 1M x 9
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None
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4MB
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(1) 1M x 36
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None
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None
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5MB
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None
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(4) 1M x 9
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(4) 256K x 9
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6MB
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(1) 512K x 36
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(4) 1M x 9
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None
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8MB
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(1) 1M x 36
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(4) 1M x 9
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None
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8MB
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(1) 2M x 36
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None
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None
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8MB
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None
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(4) 1M x 9
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(4) 1M x 9
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10MB
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(1) 512K x 36
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(4) 1M x 9
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(4) 1M x 9
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12MB
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(1) 1M x 36
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(4) 1M x 9
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(4) 1M x 9
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12MB
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(1) 2M x 36
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(4) 1M x 9
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None
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16MB
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(1) 2M x 36
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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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None
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(4) 4M x 9
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None
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DRAM CONFIGURATION (CON’T)
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Size
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Bank 0
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Bank 1
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Bank 2
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17MB
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None
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(4) 4M x 9
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(4) 256K x 9
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18MB
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(1) 512K x 36
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(4) 4M x 9
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None
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20MB
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(1) 1M x 36
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(4) 4M x 9
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None
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20MB
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None
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(4) 4M x 9
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(4) 1M x 9
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22MB
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(1) 512K x 36
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(4) 4M x 9
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(4) 1M x 9
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24MB
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(1) 1M x 36
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(4) 4M x 9
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(4) 1M x 9
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24MB
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(1) 2M x 36
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(4) 4M x 9
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None
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28MB
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(1) 2M x 36
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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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None
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(4) 4M x 9
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(4) 4M x 9
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34MB
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(1) 512K x 36
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(4) 4M x 9
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(4) 4M x 9
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36MB
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(1) 1M x 36
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(4) 4M x 9
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(4) 4M x 9
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40MB
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(1) 2M x 36
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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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U1
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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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(1) 64K x 1
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128KB
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(4) 32K x 8
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None
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(1) 8K/32K x 8
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(1) 64K x 1
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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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(1) 64K x 1
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CACHE JUMPER CONFIGURATION
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Size
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J16
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None
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Pins 1 & 2, 3 & 4, 5 & 6, 9 & 10 closed
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64KB
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Open
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128KB
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Pins 1 & 2, 5 & 6, 7 & 8 closed
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256KB
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Pins 1 & 2, 3 & 4, 5 & 6, 9 & 10 closed
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VIDEO MEMORY CONFIGURATION
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Size
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Bank 0
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Bank 1
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512KB
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512KB
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None
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1MB
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512KB
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512KB
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Note: The size of the video memory chips are unidentified.
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CPU SPEED SELECTION
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Speed
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J26
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J27
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25MHz
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Pins 1 & 2 closed
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Pins 2 & 3 closed
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33MHz
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Pins 1 & 2 closed
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Pins 1 & 2 closed
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50iMHz
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Pins 1 & 2 closed
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Pins 2 & 3 closed
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66iMHz
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Pins 1 & 2 closed
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Pins 1 & 2 closed
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CPU TYPE SELECTION
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Type
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J19
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80486SX
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Pins 1 & 3, 2 & 4 closed
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ODP486SX
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Pins 1 & 3, 2 & 4 closed
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80487SX
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Pins 1 & 3, 2 & 4 closed
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80486DX
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Pins 3 & 5, 4 & 6 closed
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ODP486DX
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Pins 3 & 5, 4 & 6 closed
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80486DX2
|
Pins 3 & 5, 4 & 6 closed
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