| <<< Differences, cont. | Index | >>> |
| The MS-DOS and Older Windows Operating Systems | |||||
|---|---|---|---|---|---|
|
Operating
System |
System Access |
Available Active Processes |
Addressable
Memory |
Contents of Segment
Register |
Word Length |
| MS-DOS and Windows real mode | Direct to hardware and OS call | One | 1 megabyte |
Actual
address |
16 bits |
| Windows 3.x virtual-86 mode | Operating system call | Multiple | 1 megabyte |
Segment
selectors |
16 bits |
| Windows 3.x protected mode | Operating system call | Multiple | 16 megabytes |
Segment
selectors |
16 bits |
| Windows NT 3.x | Operating system call | Multiple | 512 megabytes |
Segment
selectors |
32 bits |
| <<< Differences, cont. | Index | >>> |