| ??? 03/30/05 13:22 Read: times |
#90680 - my guess Responding to: ???'s previous message |
Anyone know why Intel decided to have 4 banks of 8 registers in the original 8051? I have checked the bible and all it says is that register operations are faster. OK, but why 8 registers and why 4 banks?
From reliable source: all decisions when designing the '48 and promoting the '48 to the '51 were taken with one thing in mind: make a controller, not a processor (competing with the x86) On the specifics my guess and what I have heard from sources of varying reliability: 8 registers because it is 3 bits 4 banks to facilitate the fastest ISRs in the west. 4, not 3 because 4 is two bits. Of course, with 2 int priorities 3 would do nicely, but I have seen the 4th bank used as a "save at subr entry". Erik |
| Topic | Author | Date |
| Registers | 01/01/70 00:00 | |
| my guess | 01/01/70 00:00 | |
| Participation | 01/01/70 00:00 | |
| Old Age | 01/01/70 00:00 | |
| Old but stronger still | 01/01/70 00:00 | |
| just a guess | 01/01/70 00:00 | |
| Powers of Two | 01/01/70 00:00 | |
| when all was new | 01/01/70 00:00 | |
| push and pop | 01/01/70 00:00 | |
| passing | 01/01/70 00:00 | |
| Passing Parameters | 01/01/70 00:00 | |
| yes, with a monitor | 01/01/70 00:00 | |
| Register Overlaying??? | 01/01/70 00:00 | |
| Context | 01/01/70 00:00 | |
not necessarily | 01/01/70 00:00 | |
| my point was | 01/01/70 00:00 | |
| Sausages | 01/01/70 00:00 | |
| Sausage and Chips | 01/01/70 00:00 | |
| no instructions, but gates | 01/01/70 00:00 | |
| Many Gates? | 01/01/70 00:00 |