TANDY/RADIO SHACK 486ei 25/SVR Processor 80486DX Processor Speed 25MHz Chip Set Tandy Max. Onboard DRAM 64MB SRAM Cache 256KB BIOS Phoenix Dimensions 355mm x 304mm I/O Options EGA feature connector, floppy drive interface, IDE interface, parallel port, serial port (2), VGA port (on external I/O card) NPU Options 4167 [Image] CONNECTIONS Purpose Location Purpose Location External battery J3 Reset switch W5 Speaker J15 Turbo switch W6 Power LED & keylock J16 Turbo LED W7 USER CONFIGURABLE SETTINGS Function Jumper Position » CMOS memory normal operation J2 open CMOS memory clear J2 closed » Factory configured - do not alter W1 N/A SRAM CONFIGURATION Size Bank 0 W3 W4 256KB (8) 32K x 8 closed closed DRAM CONFIGURATION Size Bank 0 Bank 1 Bank 2 Bank 3 4MB (4) 1M x 9 NONE NONE NONE 8MB (4) 1M x 9 (4) 1M x 9 NONE NONE 12MB (4) 1M x 9 (4) 1M x 9 (4) 1M x 9 NONE 16MB (4) 1M x 9 (4) 1M x 9 (4) 1M x 9 (4) 1M x 9 16MB (4) 4M x 9 NONE NONE NONE 20MB (4) 1M x 9 (4) 4M x 9 NONE NONE 24MB (4) 1M x 9 (4) 1M x 9 (4) 4M x 9 NONE 28MB (4) 1M x 9 (4) 1M x 9 (4) 1M x 9 (4) 4M x 9 32MB (4) 4M x 9 (4) 4M x 9 NONE NONE 36MB (4) 1M x 9 (4) 4M x 9 (4) 4M x 9 NONE 40MB (4) 1M x 9 (4) 1M x 9 (4) 4M x 9 (4) 4M x 9 48MB (4) 4M x 9 (4) 4M x 9 (4) 4M x 9 NONE 52MB (4) 1M x 9 (4) 4M x 9 (4) 4M x 9 (4) 4M x 9 64MB (4) 4M x 9 (4) 4M x 9 (4) 4M x 9 (4) 4M x 9 DRAM SWITCH CONFIGURATION Size SW2/switch SW2/switch SW2/switch SW2/switch SW2/switch 1 2 3 4 5 4MB closed closed closed closed closed 8MB open closed closed closed closed 12MB closed open closed closed closed 16MB open open closed closed open 16MB closed closed open closed open 20MB closed closed open open open 24MB closed open closed open open 28MB open closed closed open open 32MB open closed open closed open 36MB closed open open open open 40MB open open closed open open 48MB closed open open closed open 52MB open open open open open 64MB open open open closed open [Image] CONNECTIONS Purpose Location Purpose Location IDE drive interface J1 Serial port 2 J5 Floppy drive interface J2 IDE interface LED J6 Parallel port J3 VGA feature J7 Serial port 1 J4 EGA feature J11 SERIAL PORT 1 (J4) CONFIGURATION S1 Function Switch Switch Switch Switch Switch Switch 1 2 3 4 5 6 disabled open open open open open open COM1/IRQ4 closed open open open open closed COM2/IRQ3 open closed open open closed open COM3/IRQ4 open open closed open open closed COM4/IRQ3 open open open closed closed open SERIAL PORT 2 (J5) CONFIGURATION S3 Function Switch Switch Switch Switch Switch Switch 1 2 3 4 5 6 disabled open open open open open open COM1/IRQ4 closed open open open open closed COM2/IRQ3 open closed open open closed open COM3/IRQ4 open open closed open open closed COM4/IRQ3 open open open closed closed open PARALLEL PORT (J3) CONFIGURATION S2 Function Switch Switch Switch Switch Switch Switch 1 2 3 4 5 6 disabled open open open N/A open open LPT1/IRQ7 closed open open N/A open closed LPT2/IRQ5 open closed open N/A closed open LPT3/IRQ7 open open closed N/A open closed USER CONFIGURABLE SETTINGS Function Jumper Position » IOCHRDY signal from pin 27 enabled J8 open J9 open » IOCHRDY signal from pin 21 enabled J8 closed J9 closed » IDE interface pin 34 select PDIAG J10 open signal IDE interface pin 34 select ground J10 closed » Floppy drive interface J12 open precompensation mode select 125ns Floppy drive interface J12 closed precompensation mode select 187ns » IDE interface (J1) enabled J14 closed IDE interface (J1) disabled J14 open » On-board video enabled J15 closed On-board video disabled J15 open » Floppy drive interface (J2) J16 closed interrupt request select IRQ6 Floppy drive interface (J2) J16 open interrupt request select none » Single speed motor select J17 open Dual speed motor select J17 closed » On-board video select 16-bit mode J18 open normal On-board video force 8-bit mode J18 closed » Floppy drive disk change signal J19 closed enabled Floppy drive disk change signal J19 open disabled » Monitor type select color J20 pins 1 & 2 closed Monitor type select monochrome J20 pins 2 & 3 closed VGA feature connector disabled J22 closed VGA feature connector enabled J22 open » Floppy drive interface (J2) J23 closed enabled Floppy drive interface (J2) J23 open disabled » IDE interface (J1) interrupt J24 closed request select IRQ14 IDE interface (J1) interrupt J24 open request select none