| ??? 06/27/11 13:49 Read: times |
#182741 - both: 8048 legacy + (packed) BCD Responding to: ???'s previous message |
Richard Erlacher said:
When the 805x was first introduced, it was touted as being source code compatible with the 8048. This instruction may simply have been included in order to support that claim. It indeed *was* (together with other such, e.g. the AJMP/ACALL discussed here recently). The 8048 does have an XCHD instruction (more precisely, it has exactly *the* XCHD A,@Rn instruction). But the raw reason why 8048 did have this instruction was its strong 4-bit/BCD legacy from the times of 4004, the first microprocessor. Jan PS. Being 8051-oddities collector, XCHD is of course my FAVOURITE instruction! :-) |
| Topic | Author | Date |
| XCHD use | 01/01/70 00:00 | |
| XCHG usage | 01/01/70 00:00 | |
| Search... | 01/01/70 00:00 | |
| Re: XCHD use | 01/01/70 00:00 | |
| not generated | 01/01/70 00:00 | |
| SDCC might add pBCD type of numbers | 01/01/70 00:00 | |
| Not a good idea | 01/01/70 00:00 | |
| Depends | 01/01/70 00:00 | |
| You're right | 01/01/70 00:00 | |
| another possibility ... | 01/01/70 00:00 | |
| both: 8048 legacy + (packed) BCD | 01/01/70 00:00 | |
simple example | 01/01/70 00:00 |