Timeline for What elements of the MOS 6502 did it copy from the Motorola 6800?
Current License: CC BY-SA 4.0
12 events
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| Apr 28 at 3:38 | comment | added | cjs | BTW, there might be something in that RTI instruction. How did it compare between the 6800 and 6809, and did any other systems do it exactly the same way? It's certainly different from the 8080, which did not push the flags automatically. | |
| Apr 25 at 21:53 | comment | added | cjs | So no, I don't think that "these things are written down differently in official documentation" is really a fruitful avenue to pursue here; I'm looking for similarities in the design of the CPU itself, regardless of whether or not the documentation for them is different. | |
| Apr 25 at 21:52 | comment | added | cjs |
Some of those mnemonics clearly did not originate with the 6800; for example, BEQ is also a PDP-11 mnemonic. Others have different sets of addressing modes: LDA always loads the A register on 6502, but may load A or B accumulator on 6800, depending on the operands. Though even the existence of that mnemonic depends on your assembler, some don't use the "official" mnemonics and accept only LDAA or LDAB. And, of course, the Z80 uses a "radical new scheme" for the exact same parts of the CPU design as the 8080 for copyright reasons, yet accepts code assembled from Intel mnemonics.
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| Apr 25 at 12:37 | history | edited | Polluks | CC BY-SA 4.0 |
added 323 characters in body
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| Apr 24 at 16:41 | comment | added | dave | Instructions are what a CPU executes. Mnemonics are the input language to an assembler. You can have the same mnemonics for different instruction sets; you can have different mnemonics for the same instruction set. Is the point you're making that the instruction sets are "pretty similar"? | |
| Apr 24 at 16:10 | comment | added | Polluks | @dave Mnemonics are part of the specification, do you know an exception? | |
| Apr 24 at 16:08 | review | Low quality posts | |||
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| Apr 24 at 16:05 | history | edited | Polluks | CC BY-SA 4.0 |
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| Apr 24 at 2:53 | comment | added | dave | "Mnemonics" are not any part of a microprocessor, though. | |
| Apr 23 at 23:10 | comment | added | Greenonline |
Do you mean aren't pretty similar at all? The at all at the end sort of confuses the sentence's meaning. Also, could you edit and expand upon your answer a little bit?
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| Apr 23 at 23:00 | review | Low quality posts | |||
| Apr 24 at 8:37 | |||||
| Apr 23 at 22:40 | history | answered | Polluks | CC BY-SA 4.0 |