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# TANDY/RADIO SHACK
4825 SX
Processor 80486SX/80487SX/80486DX/80486DX2
Processor Speed 25/33/50(internal)/66(internal)MHz
Chip Set Unidentified
Video Chip Set Unidentified
Maximum Onboard 32MB
Memory
Maximum Video 1MB
Memory
Cache None
BIOS Unidentified
Dimensions 394mm x 381mm
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
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|-------------------+----------+------------------+----------|
| VGA port | CN1 | IDE interface | CN8 |
|-------------------+----------+------------------+----------|
| PS/2 mouse port | CN2 | External battery | J1 |
|-------------------+----------+------------------+----------|
| Parallel port | CN3 | Speaker | J2 |
|-------------------+----------+------------------+----------|
| Serial port 2 | CN4 | Reset switch | J3 |
|-------------------+----------+------------------+----------|
| Serial port 1 | CN5 | Power LED | J4 |
|-------------------+----------+------------------+----------|
| VGA feature | CN6 | Riser slot | SL1 |
| connector | | | |
|-------------------+----------+------------------+----------|
| Floppy drive | CN7 | | |
| interface | | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Label | Position |
|--------------------------------------+---------+-----------|
| » | CMOS memory normal operation | JP1 | Open |
|---+----------------------------------+---------+-----------|
| | CMOS memory clear | JP1 | Closed |
|---+----------------------------------+---------+-----------|
| » | Monitor frequency select 31KHz | SW1/5 | Off |
|---+----------------------------------+---------+-----------|
| | Monitor frequency select 40KHz | SW1/5 | On |
|---+----------------------------------+---------+-----------|
| » | Monitor type select color | SW2/3 | Off |
|---+----------------------------------+---------+-----------|
| | Monitor type select monochrome | SW2/3 | On |
+------------------------------------------------------------+
+------------------------------------------------------------+
| DRAM CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 |
|------------------+--------------------+--------------------|
| 4MB | (4) 1M x 9 | None |
|------------------+--------------------+--------------------|
| 5MB | (4) 1M x 9 | (4) 256K x 9 |
|------------------+--------------------+--------------------|
| 8MB | (4) 1M x 9 | (4) 1M x 9 |
|------------------+--------------------+--------------------|
| 16MB | (4) 4M x 9 | None |
|------------------+--------------------+--------------------|
| 20MB | (4) 1M x 9 | (4) 4M x 9 |
|------------------+--------------------+--------------------|
| 32MB | (4) 4M x 9 | (4) 4M x 9 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VIDEO MEMORY CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 |
|-------------------+---------------------+------------------|
| 512KB | 512KB | None |
|-------------------+---------------------+------------------|
| 1MB | 512KB | 512KB |
|------------------------------------------------------------|
| Note: The location of banks 0 & 1 are unidentified. The |
| size of the video memory chips are unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VIDEO MEMORY SWITCH CONFIGURATION |
|------------------------------------------------------------|
| Size | SW1/6 |
|------------------------------+-----------------------------|
| 512KB | On |
|------------------------------+-----------------------------|
| 1MB | Off |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE SELECTION |
|------------------------------------------------------------|
| Type | SW2/1 | SW2/2 |
|--------------------+-------------------+-------------------|
| 80486SX | Off | Off |
|--------------------+-------------------+-------------------|
| 80487SX | On | Off |
|--------------------+-------------------+-------------------|
| 80486DX | Off | Off |
|--------------------+-------------------+-------------------|
| 80486DX2 | Off | Off |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VIDEO RESOLUTION SELECTION (800 X 600) |
|------------------------------------------------------------|
| Frequency | SW1/1 | SW1/2 |
|-------------------------+-----------------+----------------|
| » | 56Hz | Off | Off |
|--------+----------------+-----------------+----------------|
| | 60Hz | Off | On |
|--------+----------------+-----------------+----------------|
| | 72Hz | On | Off |
|--------+----------------+-----------------+----------------|
| | 56Hz | On | On |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VIDEO RESOLUTION SELECTION (1024 X 768) |
|------------------------------------------------------------|
| Frequency | SW1/3 | SW1/4 |
|-------------------------+-----------------+----------------|
| » | Interlaced | Off | Off |
|---+---------------------+-----------------+----------------|
| | 60HZ non-interlaced | Off | On |
|---+---------------------+-----------------+----------------|
| | 70HZ non-interlaced | On | Off |
|---+---------------------+-----------------+----------------|
| | Interlaced | On | On |
+------------------------------------------------------------+
+------------------------------------------------------------+
| ON BOARD VIDEO SELECTION |
|------------------------------------------------------------|
| Setting | SW1/7 | SW1/8 |
|------------------------+-----------------+-----------------|
| » | Enabled | On | Off |
|---+--------------------+-----------------+-----------------|
| | Disabled | Off | On |
+------------------------------------------------------------+