| ??? 01/11/08 08:51 Read: times |
#149301 - 16 bits Responding to: ???'s previous message |
Actually, the 8088/8086 has/had an 64 KB I/O space. One form of the IN and OUT instructions takes the port address from an 8-bit immediate field within the instruction. If you want to get at ports above 255, then different forms of IN and OUT grab the port address from the DX register.
I believe this is true at least through the '486. In the later processors IN and OUT are privileged instructions, while in the 8088/8086 of course they are not. -- Russ |
| Topic | Author | Date |
| PC Ports - Just curious | 01/01/70 00:00 | |
| x86 has a separate IO space from memory space... | 01/01/70 00:00 | |
| Misunderstanding? | 01/01/70 00:00 | |
| 10bits | 01/01/70 00:00 | |
| 16 bits | 01/01/70 00:00 | |
| and more... | 01/01/70 00:00 | |
| Memory mapped? | 01/01/70 00:00 | |
| yes | 01/01/70 00:00 | |
| cache... | 01/01/70 00:00 | |
| IP Ports | 01/01/70 00:00 | |
| Yes thats what I was looking for... | 01/01/70 00:00 | |
Nothing specifically to do with PCs, then! | 01/01/70 00:00 |