Timeline for What elements of the MOS 6502 did it copy from the Motorola 6800?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 27 at 14:40 | answer | added | RETRAC | timeline score: 2 | |
| Apr 23 at 22:40 | answer | added | Polluks | timeline score: -2 | |
| Apr 21 at 6:13 | comment | added | cjs | @thebusybee I am glad you agree with me about that. Further, comments on questions are for suggesting improvements to the questions, rather than going off on irrelevant tangents. | |
| Apr 21 at 6:10 | comment | added | the busybee | @cjs Comments are not storage of important things, these sites shall provide their information without the comments. Anything important is supposed to be in the question and in the potential answers. This is not a forum. | |
| Apr 21 at 2:21 | comment | added | cjs | @Raffzahn Sorry, I misspoke in my previous comment; I meant "other microprocessor designs," as I said in my original question. But I'm sure you can find much more to quibble about that's not really related to the question. Carry on with more pointless comments! We want to make sure that the comment section is noisy enough that we can't find the important things in it! | |
| Apr 20 at 18:55 | comment | added | Raffzahn | @cjs_"...example that microprocessor designers do take elements from other microprocessor designers...", erm, no. Point is that /80 did not take elements from some other designer. Federico Faggin was lead designer for both CPU's, 8080 and Z80. The Z80 is a direct continuation of the 8080.Even more than, for example, Mitsubishi's CPUs are a direct continuations of MOS' design. | |
| Apr 20 at 18:47 | comment | added | Raffzahn | @Tommy 6502 not only rearranged it, but also used a different signal combination for cyclevalidation | |
| Apr 20 at 15:29 | comment | added | cjs | @Tommy Yes, it does. | |
| Apr 20 at 15:26 | comment | added | Jon Custer | The “6”. They copied the “6”… | |
| Apr 20 at 11:42 | comment | added | Tommy | Does the bus interface count? The 6501 is pin-compatible with the 6800, the 6502 rearranged. | |
| Apr 20 at 9:00 | comment | added | cjs | @Raffzahn "...the Z80 isn't just taking some elements...." I didn't say "taking some," I said "extensively copying." Regardless, your statement is correct but irrelevant to the question. It may not just be taking some elements, but it is indeed "taking some elements," and thus I think serves as a suitable (and particularly obvious) example that microprocessor designers do take elements from other microprocessor designers. | |
| Apr 20 at 8:49 | comment | added | Raffzahn | Having preferred address ranges isn't anything new, already the /360 design got a ZP like mode, as the first 4096 bytes were always accessible independent of any base register value. Also, note that the Z80 isn't just taking some elements, but a direct extension. After all, it a slight upgrade and simplification of the 8080, made by the very same lead designer, Frederico Faggin, intended as quick money maker to finance his real new design, the Z8. And the 6502 is essentially the same, except more extreme and with opposite targets. Faggin mainly changed the bus while MOS did go for the ISA. | |
| Apr 20 at 4:33 | comment | added | cjs | @dave Yes, that came to my mind too, but the PDP-8 was different in that it had only short addresses, so you could access its zero page only with the ZP addressing mode. The 6800 is different in that the ZP addressing mode duplicates functionality of the standard absolute addressing mode, only using a one-byte operand instead of a two-byte operand. | |
| Apr 20 at 3:25 | comment | added | dave | The PDP-8 (1965) had a zero-page address mode. | |
| Apr 20 at 2:15 | history | asked | cjs | CC BY-SA 4.0 |