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# TANDY/RADIO SHACK
2500 SX/20
Processor 80386SX
Processor Speed 20MHz
Chip Set Unidentified
Video Chip Set Unidentified
Maximum Onboard 5MB
Memory
Maximum Video Unidentified
Memory
Cache None
BIOS Unidentified
Dimensions 254mm x 218mm
I/O Options Floppy drive interface, IDE interface, serial
port, parallel port, PS/2 mouse port, riser
slot
NPU Options 80387SX
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|--------------------+-----------+----------------+----------|
| Floppy drive | CN1 | IDE interface | J1 |
| interface | | LED | |
|--------------------+-----------+----------------+----------|
| IDE interface | CN2 | Riser slot | SL1 |
|------------------------------------------------------------|
| The location of the serial port, parallel port and PS/2 |
| mouse port is unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Label | Position |
|---------------------------------------+-------+------------|
| » | Audio input source select | JP1 | Pins 1 & 2 |
| | microphone | | closed |
|---+-----------------------------------+-------+------------|
| | Audio input source select line | JP1 | Pins 2 & 3 |
| | level | | closed |
|---+-----------------------------------+-------+------------|
| » | Audio output source select | JP2 | Pins 1 & 2 |
| | headphone | | closed |
|---+-----------------------------------+-------+------------|
| | Audio output source select line | JP2 | Pins 2 & 3 |
| | level | | closed |
|---+-----------------------------------+-------+------------|
| » | Monitor type select VGA analog or | JP3 | Pins 1 & 2 |
| | standard multiple frequency | | closed |
|---+-----------------------------------+-------+------------|
| | Monitor type select non standard | JP3 | Pins 2 & 3 |
| | multiple frequency | | closed |
|---+-----------------------------------+-------+------------|
| » | VGA BIOS select PS/2 mode | JP4 | Pins 2 & 3 |
| | | | closed |
|---+-----------------------------------+-------+------------|
| | VGA BIOS select AT mode | JP4 | Pins 1 & 2 |
| | | | closed |
|---+-----------------------------------+-------+------------|
| » | Video IRQ9 disabled | JP5 | Open |
|---+-----------------------------------+-------+------------|
| | Video IRQ9 enabled | JP5 | Pins 1 & 2 |
| | | | closed |
|---+-----------------------------------+-------+------------|
| » | On board video enabled | JP6 | Pins 1 & 2 |
| | | | closed |
|---+-----------------------------------+-------+------------|
| | On board video disabled | JP6 | Pins 2 & 3 |
| | | | closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| DRAM CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | Bank 2 |
|---------+----------+------------------------+--------------|
| 1.5MB | 1MB | (2) 256K x 9 | None |
|---------+----------+------------------------+--------------|
| 2MB | 1MB | (2) 256K x 9 | (2) 256K x 9 |
|---------+----------+------------------------+--------------|
| 3MB | 1MB | (2) 1M x 9 | None |
|---------+----------+------------------------+--------------|
| 5MB | 1MB | (2) 1M x 9 | (2) 1M x 9 |
|------------------------------------------------------------|
| Note: Bank 0 is factory installed and is not |
| configurable. The location is unidentified. |
+------------------------------------------------------------+