When I started at Burroughs, they had just started a project
> to increase amount of memory that could be accessed by
> an application on the medium systems (B3500) line. The
> B3500 had a flat one million digit address space and
> could run in ‘control state’ or ‘normal state’. When the
> base register had the value zero, the processor ran in
> control state and privileged instructions were available,
> otherwise the processor was is normal state and the
> 1md address space started at the privileged base register and
> ended at the privileged limit register.
That’s an interesting approach! I had no idea how the Medium Systems line worked.
You’d think you’d see a lot of experimentation around things like this nowadays that you can get your own open-source chip design fabbed through Tiny Tapeout for US$300, including in IHP’s 350GHz 130nm SiGe BiCMOS process. (Not 350MHz; fT is 350GHz.)
Without Tiny Tapeout, IHP’s MPW price for that “SG13G2” process is €7300/mm² with a minimum of 0.8mm², which I find a rather daunting pricetag for something that probably won’t work the first time. As I understand it, that kind of thing is what sunk Chuck Moore’s chip design efforts at iTV in the 90s: they didn’t have enough capital to iterate fast enough with MPW runs through MOSIS to ever ship a working chip.
New approaches to protection seem like an especially promising area as we smash headfirst into the “vulnpocalypse” and AI generates exploits for the swiss-cheese computer systems the whole internet is built on.
Kragen