On Wed, Feb 1, 2017 at 12:56 PM, Noel Chiappa <j...@mercury.lcs.mit.edu> wrote:
> > From: William Degnan > > > 64K. > > That's 64KB, right? DEC used to talk of PDP-11 memory in words, back in the > day, so it's never quite clear unless the 'B' or 'W' is specified. > > Anyway, 64KB out to be enough to run most things. I have't looked to see > how > big a system with just RL and DL drivers, and a minimum number of disk > buffers > (that's probably the easiest way to get the size down almost as far as it > will > go) is, but it's probably in the region of 30-35KB (20KB text, and 10-15 KB > data). That leaves plenty for user processes (not max sized, of course). > > > I'd like to get another M7891, mine is only 1/2 populated. > > Oh, so that must have been 64KW - 128KB. That will give you plenty of room > for > a decent-sized kernel, and user processes. Wonder why it won't boot, then? > > Anyway, those are pretty rare. I have a couple of spare M7847's; they're > only > 32KB, but they'd help. You've got a couple of spare hex MUD slots now in > the > DD11-C, right? Speaking of which, where is the M7891 plugged in? It > couldn't > go in the DD11-B, or in the CPU backplane? > > > > typing anything kills the CPU and I have to restart the system.. > > Sorry, need exact details: after the '!' prompt, anything you type kills > the system on the first character? Or only "rlunix<CR>" does? How about > "foobar<CR>"? I'd have to look at the bootstrap source, but I think > typing a non-existing file name should take you back to the top-level > prompt. > > Noel > I just tried booting this in simh (as an 11/40 with 64k) and the cpu halts after entering "rlunix<CR>" (Entering an invalid name just returns you to the "!" prompt). Configuring simh as an 11/45 allows it to boot. Looks like you'll need to rebuild the kernel with support for the 11/40. - Josh
