TANDY/RADIO SHACK
425SX/T, 433SX/T, 433DX/T, 450DX2/T, 466DX2/T
Processor |
80486SX/ODP486SX/80487SX/80486DX/ODP486SX/80486DX2 |
Processor Speed |
25/33/50(internal)/66(internal)MHz |
Chip Set |
Unidentified |
Video Chip Set |
Unidentified |
Maximum Onboard Memory |
40MB |
Maximum Video Memory |
1MB |
Cache |
64/128/256KB |
BIOS |
Phoenix |
Dimensions |
330mm x 218mm |
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 |
CONNECTIONS | |||
Purpose |
Location |
Purpose |
Location |
VGA port |
CN1 |
Reset switch |
CN8 |
Parallel port |
CN2 |
External battery |
J7 |
Serial port 1 |
CN3 |
IDE interface |
J17 |
Serial port 2 |
CN4 |
Floppy drive interface |
J18 |
PS/2 mouse port |
CN5 |
VGA feature connector |
J21 |
IDE interface LED |
CN6 |
Riser slot |
SL1 |
Power LED & keylock |
CN7 |
USER CONFIGURABLE SETTINGS | |||
Function |
Label |
Position | |
» |
Factory configured - do not alter |
J9 |
Pins 1 & 2 closed |
» |
Factory configured - do not alter |
J11 |
Open |
» |
Factory configured - do not alter |
J13 |
Pins 1 & 2 closed |
» |
Factory configured - do not alter |
J14 |
Pins 2 & 3 closed |
» |
CMOS memory normal operation |
J20 |
Closed |
CMOS memory clear |
J20 |
Open | |
» |
On board video enabled |
J28 |
Pins 2 & 3 closed |
On board video disabled |
J28 |
Pins 1 & 2 closed | |
» |
Factory configured - do not alter |
J29 |
Open |
» |
Floppy drive write protect disabled |
J30 |
Pins 2 & 3 closed |
Floppy drive write protect enabled |
J30 |
Pins 1 & 2 closed | |
» |
Factory configured - do not alter |
J31 |
Pins 2 & 3 closed |
» |
Zero wait state enabled |
J32 |
Closed |
Zero wait state disabled |
J32 |
Open |
DRAM CONFIGURATION | |||
Size |
Bank 0 |
Bank 1 |
Bank 2 |
1MB |
(1) 256K x 36 |
None |
None |
2MB |
None |
(4) 256K x 9 |
(4) 256K x 9 |
2MB |
(1) 512K x 36 |
None |
None |
4MB |
None |
(4) 1M x 9 |
None |
4MB |
(1) 1M x 36 |
None |
None |
5MB |
None |
(4) 1M x 9 |
(4) 256K x 9 |
6MB |
(1) 512K x 36 |
(4) 1M x 9 |
None |
8MB |
(1) 1M x 36 |
(4) 1M x 9 |
None |
8MB |
(1) 2M x 36 |
None |
None |
8MB |
None |
(4) 1M x 9 |
(4) 1M x 9 |
10MB |
(1) 512K x 36 |
(4) 1M x 9 |
(4) 1M x 9 |
12MB |
(1) 1M x 36 |
(4) 1M x 9 |
(4) 1M x 9 |
12MB |
(1) 2M x 36 |
(4) 1M x 9 |
None |
16MB |
(1) 2M x 36 |
(4) 1M x 9 |
(4) 1M x 9 |
16MB |
None |
(4) 4M x 9 |
None |
DRAM CONFIGURATION (CON’T) | |||
Size |
Bank 0 |
Bank 1 |
Bank 2 |
17MB |
None |
(4) 4M x 9 |
(4) 256K x 9 |
18MB |
(1) 512K x 36 |
(4) 4M x 9 |
None |
20MB |
(1) 1M x 36 |
(4) 4M x 9 |
None |
20MB |
None |
(4) 4M x 9 |
(4) 1M x 9 |
22MB |
(1) 512K x 36 |
(4) 4M x 9 |
(4) 1M x 9 |
24MB |
(1) 1M x 36 |
(4) 4M x 9 |
(4) 1M x 9 |
24MB |
(1) 2M x 36 |
(4) 4M x 9 |
None |
28MB |
(1) 2M x 36 |
(4) 4M x 9 |
(4) 1M x 9 |
32MB |
None |
(4) 4M x 9 |
(4) 4M x 9 |
34MB |
(1) 512K x 36 |
(4) 4M x 9 |
(4) 4M x 9 |
36MB |
(1) 1M x 36 |
(4) 4M x 9 |
(4) 4M x 9 |
40MB |
(1) 2M x 36 |
(4) 4M x 9 |
(4) 4M x 9 |
CACHE CONFIGURATION | ||||
Size |
Bank 0 |
Bank 1 |
TAG |
U1 |
64KB |
(4) 8K x 8 |
(4) 8K x 8 |
(1) 8K x 8 |
(1) 64K x 1 |
128KB |
(4) 32K x 8 |
None |
(1) 8K/32K x 8 |
(1) 64K x 1 |
256KB |
(4) 32K x 8 |
(4) 32K x 8 |
(1) 32K x 8 |
(1) 64K x 1 |
CACHE JUMPER CONFIGURATION | |
Size |
J16 |
None |
Pins 1 & 2, 3 & 4, 5 & 6, 9 & 10 closed |
64KB |
Open |
128KB |
Pins 1 & 2, 5 & 6, 7 & 8 closed |
256KB |
Pins 1 & 2, 3 & 4, 5 & 6, 9 & 10 closed |
VIDEO MEMORY CONFIGURATION | ||
Size |
Bank 0 |
Bank 1 |
512KB |
512KB |
None |
1MB |
512KB |
512KB |
Note: The size of the video memory chips are unidentified. |
CPU SPEED SELECTION | ||
Speed |
J26 |
J27 |
25MHz |
Pins 1 & 2 closed |
Pins 2 & 3 closed |
33MHz |
Pins 1 & 2 closed |
Pins 1 & 2 closed |
50iMHz |
Pins 1 & 2 closed |
Pins 2 & 3 closed |
66iMHz |
Pins 1 & 2 closed |
Pins 1 & 2 closed |
CPU TYPE SELECTION | |
Type |
J19 |
80486SX |
Pins 1 & 3, 2 & 4 closed |
ODP486SX |
Pins 1 & 3, 2 & 4 closed |
80487SX |
Pins 1 & 3, 2 & 4 closed |
80486DX |
Pins 3 & 5, 4 & 6 closed |
ODP486DX |
Pins 3 & 5, 4 & 6 closed |
80486DX2 |
Pins 3 & 5, 4 & 6 closed |