From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave@horsfall.org (Dave Horsfall) Date: Wed, 7 Jan 2015 17:29:45 +1100 (EST) Subject: [TUHS] pdp11 UNIX memory allocation. In-Reply-To: <2509FDBD-67C4-4552-BB58-01281049DCB6@ronnatalie.com> References: <54AC4394.3050302@update.uu.se> <1420576433.410248.210385277.513EF8EC@webmail.messagingengine.com> <5E62DDAA-0055-46FB-8077-92DB856DEEE0@ronnatalie.com> <2509FDBD-67C4-4552-BB58-01281049DCB6@ronnatalie.com> Message-ID: On Tue, 6 Jan 2015, Ronald Natalie wrote: > Yep, the only time this [the 407 magic number] was ever trully useful > was so you could put an a.out directly into the boot block I think. But why would you include an a.out header in a boot block? When you only had 512 bytes, every one of 'em counted, and I, oops, I mean others, had to resort to vile stuff such as self-modifying code... > During normal operations the a.out header was never actually loaded into > the user memory. I heard a story that on sufficiently-early Unices, the header was indeed loaded, hence the "407". Any grey-beards here like to comment? -- Dave Horsfall DTM (VK2KFU) "Bliss is a MacBook with a FreeBSD server." http://www.horsfall.org/spam.html (and check the home page whilst you're there)