3 ms·

Sure, it's a decent idea. You can even make it fast if you cheat. I believe that the PDP-10 (well, some versions) had the first few memory locations equivalent

by kabdib 9y ago

Sure, it's a decent idea. You can even make it fast if you cheat. I believe that the PDP-10 (well, some versions) had the first few memory locations equivalent to registers. The AT&T Hobbit (Aka Crisp) chip had a stack pointer, and aggressively cached memory around the stack, essentially. Once cached, stack-relative memory operations were as fast as registers. (The Apple Newton was going to use the Hobbit, but switched to ARM when it became clear that AT&T wasn't truly interested in committing to consumer grade pricing of the CPUs).

bronson 9y ago
Huh! The first BeBoxes were built around the Hobbit as well. The switch to PowerPC happened when it was clear that its performance and addressing were always going to be weird. Not sure it even got to the point of discussing volume.
gumby 9y ago
> I believe that the PDP-10 (well, some versions) had the first few memory locations equivalent to registers. Essentially. Actually the registers were addressable as the first 16 addresses in memory for all models. For the PDP-6 and first PDP-10 (model KA) the registers were fast semiconductor devices (DTL, as I believe it predated TTL) while the rest of memory was literally core (convenient for when the power went out, as happened occasionally in Cambridge -- whatever process was running died since the registers were lost, but everything else was in core, so the machine could just be restarted). Since they were addressable you could run code out of them, like bootstrap routines or some deranged TECO code I once wrote). On the other hand any word of memory could be used as a stack pointer (two addresses fit in a word, so one half was the base and the other half the depth). It was quite a RISC-like, highly symmetrical architecture for its time and a pleasure to program. I still miss it.
octetta 9y ago
There were was a PC modem board that had the Hobbit in it. I can't seem to find any references to it online though.
deleted 9y ago
[deleted]

by kabdib 9y ago

bronson 9y ago

Huh! The first BeBoxes were built around the Hobbit as well. The switch to PowerPC happened when it was clear that its performance and addressing were always going to be weird. Not sure it even got to the point of discussing volume.

gumby 9y ago

> I believe that the PDP-10 (well, some versions) had the first few memory locations equivalent to registers. Essentially. Actually the registers were addressable as the first 16 addresses in memory for all models. For the PDP-6 and first PDP-10 (model KA) the registers were fast semiconductor devices (DTL, as I believe it predated TTL) while the rest of memory was literally core (convenient for when the power went out, as happened occasionally in Cambridge -- whatever process was running died since the registers were lost, but everything else was in core, so the machine could just be restarted). Since they were addressable you could run code out of them, like bootstrap routines or some deranged TECO code I once wrote). On the other hand any word of memory could be used as a stack pointer (two addresses fit in a word, so one half was the base and the other half the depth). It was quite a RISC-like, highly symmetrical architecture for its time and a pleasure to program. I still miss it.

octetta 9y ago

There were was a PC modem board that had the Hobbit in it. I can't seem to find any references to it online though.

deleted 9y ago

[deleted]