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I emailed this question to Steve Ness, who worked at Mark Williams Company from 1977 through 1995 on Coherent and other projects. This is his answer, which I share with permission: Mark Williams Co. used a PDP-11 as development platform before COHERENT came up, once COHERENT booted all development shifted quickly to COHERENT-based. [...] MWC never had any ...


That date is 2**32 30Hz ticks since the modern Unix epoch: $ perl -E 'say scalar gmtime(2**32 / 30)' Tue Jul 16 00:12:56 1974


According to this article and a few others around the net, Coherent was originally written on and for the DEC PDP -11. It was then ported to other processors, including x86.


Doing a search on The UNIX Historical Society for 'overlay', the earliest reference I could find was on 2.9BSD. There seemed to be a system call designed specifically to support overlays. No doubt the life span was limited, as Virtual Memory pretty much eliminated any need for overlays.


[Edit: Found a page about the Minix 3 PM supporting my memory.] Backgound When looking from today's perspective back, it's always important to as well look at usage of terms. 'MMU' and Memory Management are used interchangeable and most automatically include Address Translation and Memory Protection (often as well Paging). But that's a false shortcut based ...

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