IBM CORPORATION
PERSONAL SYSTEM/2 HMM
| 
 Processor  | 
 80486SX/80486DX/80486DX2/80486DX4/P24T  | 
| 
 Processor Speed  | 
 25/33/50(internal/66(internal)/75(internal)/100(internal)/MHz  | 
| 
 Chip Set  | 
 Unidentified  | 
| 
 Video Chip Set  | 
 None  | 
| 
 Maximum Onboard Memory  | 
 Unidentified  | 
| 
 Maximum Video Memory  | 
 None  | 
| 
 Cache  | 
 128/256KB  | 
| 
 BIOS  | 
 Unidentified  | 
| 
 Dimensions  | 
 254mm x 218mm  | 
| 
 I/O Options  | 
 32-bit PCI slots (3), floppy drive interface, IDE interfaces (2), parallel port, PS/2 mouse port, serial ports (2)  | 
| 
 NPU Options  | 
 None  | 
| 
 CONNECTIONS  | |||
| 
 Purpose  | 
 Location  | 
 Purpose  | 
 Location  | 
| 
 PS/2 mouse port  | 
 J2  | 
 IDE interface 1  | 
 J21  | 
| 
 Speaker  | 
 J5  | 
 IDE interface 2  | 
 J22  | 
| 
 Parallel port  | 
 J8  | 
 32-bit PCI slots  | 
 PC1 – PC3  | 
| 
 Floppy drive interface  | 
 J9  | 
 Power LED  | 
 W12  | 
| 
 Serial port 2  | 
 J10  | 
 IDE interface LED (PCI)  | 
 W39  | 
| 
 Serial port 1  | 
 J11  | 
 IDE interface LED (ISA)  | 
 W46  | 
| 
 USER CONFIGURABLE SETTINGS  | |||
| 
 Function  | 
 Label  | 
 Position  | |
| 
 »  | 
 Secondary cache write select write back  | 
 W1  | 
 Pins 2 & 3 closed  | 
| 
 Secondary cache write select write through  | 
 W1  | 
 Pins 1 & 2 closed  | |
| 
 »  | 
 Internal cache write select write through  | 
 W4  | 
 Open  | 
| 
 Internal cache write select write back  | 
 W4  | 
 Closed  | |
| 
 »  | 
 Flash BIOS normal operation  | 
 W6  | 
 Pins 2 & 3 closed  | 
| 
 Flash BIOS recovery mode  | 
 W6  | 
 Pins 1 & 2 closed  | |
| 
 »  | 
 Factory configured - do not alter  | 
 W8  | 
 Closed  | 
| 
 »  | 
 PS/2 mouse installed  | 
 W10  | 
 Closed  | 
| 
 PS/2 mouse not installed  | 
 W10  | 
 Open  | |
| 
 Parity generation select DPU  | 
 W17  | 
 Pins 1 & 2 closed  | |
| 
 Parity generation select CPU  | 
 W17  | 
 Pins 2 & 3 closed  | |
| 
 »  | 
 DPU does not force parity  | 
 W18  | 
 Pins 2 & 3 closed  | 
| 
 DPU forces parity  | 
 W18  | 
 Pins 1 & 2 closed  | |
| 
 »  | 
 Factory configured - do not alter  | 
 W19  | 
 Closed  | 
| 
 »  | 
 Cache installed  | 
 W21  | 
 Open  | 
| 
 Cache not installed  | 
 W21  | 
 Closed  | |
| 
 DRAM CONFIGURATION  | 
| 
 Note: The maximum size and configuration is unidentified.  | 
| 
 CACHE CONFIGURATION  | 
| 
 Note: The location and configuration is unidentified.  | 
| 
 CACHE JUMPER SELECTION  | |||
| 
 Size  | 
 W5  | 
 W22  | 
 W23  | 
| 
 128KB  | 
 Open  | 
 Closed  | 
 Open  | 
| 
 256KB  | 
 Closed  | 
 Open  | 
 Closed  | 
| 
 CACHE TAG SELECTION  | |||
| 
 Size  | 
 W24  | 
 W26  | |
| 
 7-bit  | 
 Open  | 
 Closed  | |
| 
 8-bit  | 
 Closed  | 
 Closed  | |
| » | 
 9-bit  | 
 Closed  | 
 Open  | 
| 
 CPU SPEED SELECTION  | ||
| 
 Speed  | 
 W16  | 
 W20  | 
| 
 25MHz  | 
 Open  | 
 Closed  | 
| 
 33MHz  | 
 Closed  | 
 Open  | 
| 
 50iMHz  | 
 Open  | 
 Closed  | 
| 
 66iMHz  | 
 Closed  | 
 Open  | 
| 
 75iMHz  | 
 Open  | 
 Closed  | 
| 
 100iMHz  | 
 Closed  | 
 Open  | 
| 
 CPU TYPE SELECTION  | ||
| 
 Type  | 
 W2  | 
 W3  | 
| 
 80486SX  | 
 Pins 2 & 3 closed  | 
 Closed  | 
| 
 80486DX  | 
 Pins 1 & 2, 3 & 4 closed  | 
 Closed  | 
| 
 80486DX2  | 
 Pins 1 & 2, 3 & 4 closed  | 
 Closed  | 
| 
 80486DX4  | 
 Pins 1 & 2, 3 & 4 closed  | 
 Closed  | 
| 
 P24T  | 
 Pins 1 & 2, 3 & 4 closed  | 
 Open  | 
| 
 CPU MULTIPLIER SELECTION  | |
| 
 Multiplier  | 
 W33  | 
| 
 1x  | 
 Pins 1 & 2 closed  | 
| 
 2x  | 
 Pins 2 & 3 closed  | 
| 
 3x  | 
 Open  | 
| 
 DMA CHANNEL SELECTION  | ||
| 
 Channel  | 
 W43  | |
| » | 
 ISA IDE used P10 transfer  | 
 Open  | 
| 
 6  | 
 Pins 1 & 2 closed  | |
| 
 7  | 
 Pins 2 & 3 closed  | |
| 
 ISA IDE IRQ SELECTION  | |
| 
 IRQ  | 
 W42  | 
| 
 IRQ14  | 
 Pins 1 & 2 closed  | 
| 
 IRQ15  | 
 Pins 2 & 3 closed  | 
| 
 PCI IDE IRQ SELECTION  | |||
| 
 IRQ  | 
 W35  | 
 W38  | |
| » | 
 IRQ14  | 
 Closed  | 
 Open  | 
| 
 IRQ15  | 
 Open  | 
 Closed  | |
| 
 PCI INTERRUPT SELECTION  | |
| 
 Setting  | 
 W37  | 
| 
 INTR_A enabled  | 
 Closed  | 
| 
 INTR_A disabled  | 
 Open  | 
| 
 PCI COMPLIANT IRQ SELECTION  | |
| 
 IRQ  | 
 J101  | 
| 
 IRQ1  | 
 Pin 2  | 
| 
 IRQ3  | 
 Pin 3  | 
| 
 IRQ4  | 
 Pin 4  | 
| 
 IRQ5  | 
 Pin 5  | 
| 
 IRQ6  | 
 Pin 6  | 
| 
 IRQ7  | 
 Pin 7  | 
| 
 IRQ8  | 
 Pin 8  | 
| 
 IRQ9  | 
 Pin 9  | 
| 
 IRQ10  | 
 Pin 10  | 
| 
 IRQ11  | 
 Pin 11  | 
| 
 IRQ12  | 
 Pin 12  | 
| 
 IRQ14  | 
 Pin 13  | 
| 
 IRQ15  | 
 Pin 14  |