Having worked on the v6 kernel on the 11/70 it was split on that version on that hardware. On Thu, Aug 3, 2023, 5:10 PM Ronald Natalie wrote: > Having cut my UNIX teeth on the JHU 11/45, I can tell you very much that > it did have split I/D. V6 supported split I/D for user mode programs. > The kernel originally wasn’t split I/D. Version 7, if I’m recalling > properly, did run the kernel split I/D on the 45 and 70. > > > > ------ Original Message ------ > From "Kenneth Goodwin" > To "Will Senn" > Cc "The Eunuchs Hysterical Society" > Date 8/3/23, 5:05:31 PM > Subject [TUHS] Re: Split addressing (I/D) space (inspired by the death of > the python... thread) > > At the risk of exposing my ignorance and thus being events long long ago > in history.... > And my mind now old and feeble... > > 😆 🤣 > > 1. I don't think the 11/45 had split I & d. > But I could be wrong. > That did not appear until the 11/70 > And was in the later generation 11/44 several years later. > > 2. The kernel determined it by MMU type and managed it solely. The > assembler and loader always built the binary object file as the three > sections - instructions, data and bss spaces so loading an object file > could be done on any platform. > Programmers generally did not worry about the underlying hardware > > 3. I don't recall if a systype style system call was available in v7 to > give you a machine type to switch off of. > > With something like that you could determine memory availability hard > limits on the DATA/bss side if you needed to. > > But that was also easily determined by a allocation failure in malloc/sbrk > with an out of memory error. > > If you really needed to know availability, you could have a start up > subroutine that would loop trying to malloc ever decreasing memory sizes > until success and until out of available memory error. > Then release it all back via free(). Or manage it internally. > > As I recall however vaguely, there was an attempt to split the kernel > into two pieces. One running in kernel mode and one running in supervisor > mode in order to double the amount of available instruction and data > spaces for the operating system. I recall playing around with what was > there trying to get it to work right. > I was trying to support over 200 users on a pdp 11/70 at the time running > a massive insurance database system. > > On Thu, Aug 3, 2023, 4:35 PM Will Senn wrote: > >> Does unix (v7) know about the PDP-11 45's split I/D space through >> configuration or is it convention and programmer's responsibility to >> know and manage what's actually available? >> >> Will >> >> On 8/3/23 12:00, Rich Salz wrote: >> > What, we all need something to kick now that we've beaten sendmail? >> > How about something unix, ideally a decade old? >> >>