Timeline for Did any processor ISA have a "reversed accumulator" architecture?
Current License: CC BY-SA 4.0
17 events
| when toggle format | what | by | license | comment | |
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| Oct 28 at 16:20 | comment | added | v-rob | @dave Heh, perhaps I should have specified basic single/double accumulator systems to narrow things down--I didn't think about the PDP-10 accumulator nomenclature. I would probably call them general-purpose registers myself, but that could definitely be up for debate. | |
| Oct 28 at 16:17 | vote | accept | v-rob | ||
| Oct 28 at 14:41 | answer | added | supercat | timeline score: 6 | |
| Oct 28 at 12:54 | comment | added | dave | The majority of PDP-6 / PDP-10 operations go both ways, implemented as distinct instructions. ADD: add memory to accumulator; ADDM: add accumulator to memory. Of course, you can debate whether those machines have 16 'accumulators' (as per the doc) or 16 'registers'. | |
| Oct 28 at 12:54 | answer | added | John Doty | timeline score: 8 | |
| Oct 28 at 12:16 | answer | added | Raffzahn | timeline score: 8 | |
| Oct 28 at 12:04 | comment | added | Michael Graf | @PatrickSchlüter — precisely :D Now ask yourself: What kind of language is Intercal? | |
| Oct 28 at 11:46 | comment | added | Patrick Schlüter | @Michael Graf C-Intercal implemented COMEFROM. It even used it to implement threading. | |
| Oct 28 at 11:44 | answer | added | Patrick Schlüter | timeline score: 9 | |
| Oct 28 at 11:20 | comment | added | Raffzahn | @v-rob For one those instructions (inc, dec, ldy, etc) do not involve the accumulator - which is the main premise here (and of an accumulator machine in general). | |
| Oct 28 at 11:09 | history | became hot network question | |||
| Oct 28 at 7:29 | comment | added | Michael Graf | "Have there ever been programming languages that used a COMEFROM rather than GOTO construct?" | |
| Oct 28 at 7:08 | answer | added | the busybee | timeline score: 13 | |
| Oct 28 at 5:13 | history | edited | TonyM | CC BY-SA 4.0 | Replaced 'fourth' with more common and readily-understandable 'quarter'. |
| Oct 28 at 4:51 | comment | added | v-rob | I don't buy that argument. Both the Z80 and the 6502 had instructions that could use non-accumulator registers and memory as combined source/destinations, such as inc d or inc (hl) for the Z80. Extremely basic accumulator machines may not have this sort of functionality, sure, but most that I've seen do. | |
| Oct 28 at 4:09 | comment | added | user3528438 | Register write back is very complex and takes a lot of time. Modern processors has a lot of forwarding circuit to make the result available to the next instruction even though it hasn't reached the register file. This goes against the very reason to use an accumulator model: simplicity. | |
| Oct 28 at 3:07 | history | asked | v-rob | CC BY-SA 4.0 |