486ei 25/SVR Motherboard Settings and Configuration
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 |
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 1 | SW2/switch 2 | SW2/switch 3 | SW2/switch 4 | SW2/switch 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 |
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 1 | Switch 2 | Switch 3 | Switch 4 | Switch 5 | Switch 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 1 | Switch 2 | Switch 3 | Switch 4 | Switch 5 | Switch 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 1 | Switch 2 | Switch 3 | Switch 4 | Switch 5 | Switch 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 J9 | open open |
| » | IOCHRDY signal from pin 21 enabled | J8 J9 | closed closed |
| » | IDE interface pin 34 select PDIAG signal | J10 | open |
IDE interface pin 34 select ground | J10 | closed | |
| » | Floppy drive interface precompensation mode select 125ns | J12 | open |
Floppy drive interface precompensation mode select 187ns | J12 | closed | |
| » | 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) interrupt request select IRQ6 | J16 | closed |
Floppy drive interface (J2) interrupt request select none | J16 | open | |
| » | Single speed motor select | J17 | open |
Dual speed motor select | J17 | closed | |
| » | On-board video select 16-bit mode normal | J18 | open |
On-board video force 8-bit mode | J18 | closed | |
| » | Floppy drive disk change signal enabled | J19 | closed |
Floppy drive disk change signal disabled | J19 | open | |
| » | 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) enabled | J23 | closed |
Floppy drive interface (J2) disabled | J23 | open | |
| » | IDE interface (J1) interrupt request select IRQ14 | J24 | closed |
IDE interface (J1) interrupt request select none | J24 | open | |
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