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# TANDY/RADIO SHACK
486ei 25/SVR
Processor 80486DX
Processor Speed 25MHz
Chip Set Tandy
Max. Onboard 64MB
DRAM
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
IMG IMG 1
+------------------------------------------------------------+
| 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 |
+------------------------------------------------------------+
IMG IMG 2
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|---------------------+----------+----------------+----------|
| IDE drive interface | J1 | Serial port 2 | J5 |
|---------------------+----------+----------------+----------|
| Floppy drive | J2 | IDE interface | J6 |
| interface | | LED | |
|---------------------+----------+----------------+----------|
| 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 |Switch |Switch |
| | | | | 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 1|Switch 2|Switch 3|Switch |Switch |Switch |
| | | | | 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 1|Switch 2|Switch 3|Switch |Switch |Switch |
| | | | | 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 | J8 | open |
| | enabled | | |
| | | J9 | open |
|---+----------------------------------+--------+------------|
| » | IOCHRDY signal from pin 21 | J8 | closed |
| | enabled | | |
| | | J9 | closed |
|---+----------------------------------+--------+------------|
| » | IDE interface pin 34 select | J10 | open |
| | PDIAG signal | | |
|---+----------------------------------+--------+------------|
| | IDE interface pin 34 select | J10 | closed |
| | ground | | |
|---+----------------------------------+--------+------------|
| » | 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 | J18 | open |
| | mode 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 | | |
+------------------------------------------------------------+