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