The Unix Heritage Society mailing list
 help / color / mirror / Atom feed
* [TUHS] Apple IIe Unix?
@ 2020-11-26 21:55 will.senn
  2020-11-26 22:22 ` usotsuki
                   ` (5 more replies)
  0 siblings, 6 replies; 18+ messages in thread
From: will.senn @ 2020-11-26 21:55 UTC (permalink / raw)


Hi All,

So, I'm about to get my very own Apple IIe and while it's an incredibly 
versatile machine for assembly language and hardware hackery, I'm not 
aware of any Unices that run on the machine, natively. Does anybody know 
of any from back in the day?

It's got a 65c02 processor and somewhere around 128k of RAM, but it's 
also pretty expandable w/7 slots and a huge amount of literature about 
how to do stuff w/those slots.

Thanks,

Will

-- 
GPG Fingerprint: 68F4 B3BD 1730 555A 4462  7D45 3EAA 5B6D A982 BAAF

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://minnie.tuhs.org/pipermail/tuhs/attachments/20201126/012df01c/attachment.htm>


^ permalink raw reply	[flat|nested] 18+ messages in thread
* [TUHS] Apple IIe Unix?
@ 2020-11-27 11:54 jnc
  2020-11-27 12:20 ` usotsuki
                   ` (2 more replies)
  0 siblings, 3 replies; 18+ messages in thread
From: jnc @ 2020-11-27 11:54 UTC (permalink / raw)


    > From: Steve Nickolas

    > there's no easy way to do preemptive multitasking without extra
    > hardware.

Perhaps you're using some idiosyncratic definition of "preemptive" and
"multitasking", but to me that statement's not accurate.

Let's take the "multitasking" part first: that just means 'two or more
computations can run at the same time, sharing the machine' - and that's not
hard to do, without special hardware, provided there's some way (in the
organization of the software) to save the state of one when the other is
running. Many simple systems do this; e.g. the MOS system that I used on
LSI-11's, BITD.

"Preemptive" is a bit trickier, because things have to be organized so that
one 'task' can be temporarily stopped arbitrarily (i.e. without it explicitly
giving up the processor, which is what e.g.MOS did) to let another run. There
does need to be some asynchronous way of inciting the second 'task' to run,
but interrupts (either clock, or device) do that, and pretty much every
machine has those. MINI-UNIX, for example, has premptive multitasking.

The thing that takes special hardware is _protecting_ one task from a bug in
another - a bug which could trash the first tasks's (or the system's!)
memory. One has to have memory management of some kind to do that.


    > From: Dave Horsfall

    > I would start with something like Mini-Unix

MINI-UNIX would be a good place to start if one wanted to bring up a system on
a machine without memory management; there's nothing in the kernel which is
PDP-11 dependent that I can think of (unlike V6, which had a fairly heavy
dependency on the PDP-11 memory management hardware - although one could of
course rip that all out, as MINI-UNIX did).

However, one's still looking at a fair amount of work, both to get rid of any
traces of PDP-11isms (e.g. stack growth direction), and translate the
assembler part (startup, and access to non-C operations). Something like FUZIX
might be an easier option.

       Noel


^ permalink raw reply	[flat|nested] 18+ messages in thread
[parent not found: <20201201160105.1359e68b.ref@algol>]

end of thread, other threads:[~2020-12-03 18:58 UTC | newest]

Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-26 21:55 [TUHS] Apple IIe Unix? will.senn
2020-11-26 22:22 ` usotsuki
2020-11-26 22:30 ` nikke.karlsson
2020-11-27  0:24   ` drsalists
2020-11-26 22:47 ` dave
2020-11-26 23:07   ` katolaz
2020-11-26 23:00 ` clemc
2020-11-27  0:47   ` athornton
2020-11-27  3:16   ` usotsuki
2020-11-26 23:22 ` jason-tuhs
2020-11-27  3:18   ` usotsuki
2020-12-03 18:40 ` Chris Hanson
2020-11-27 11:54 jnc
2020-11-27 12:20 ` usotsuki
2020-11-27 16:22 ` cowan
2020-11-28 23:12 ` dave
     [not found] <20201201160105.1359e68b.ref@algol>
2020-12-01 15:01 ` Jose R. Valverde via TUHS
2020-12-01 15:48   ` Will Senn

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).