[TUHS] Re-implementations/Clean-Rooms et al.

[Steve Nickolas]

On Thu, 8 Sep 2022, Larry McVoy wrote:

> On Thu, Sep 08, 2022 at 08:05:44PM -0400, Steve Nickolas wrote:
>>
>> I'm probably the only one brazen enough to put it to the test.
>>
>> For some years, I've wanted to create a free implementation of System V, and
>> then move on from there.  (I know there's limited utility for such a thing,
>> because of the BSDs.)
>
> Why?  Have you booted 32V?  Run in it for a while?  No VM, no networking,
> very basic system.  Other than historical, I don't understand the point.

Wasn't so much about 32V itself, as 32V being potentially clear and the 
source for a lot of SysV, that having 32V would make rewriting SysV a lot 
easier. 🤪

I've used v7/386, which is probably a comparable system.

>> A few things actually hinge on this.  If it were considered a fact, and not
>> a mere opinion, that 32V was PD, then I could be sure that certain things
>> were safe to use, rather than having to rewrite (including some particularly
>> tricky stuff the BSDs never fully reimplemented, like diff(1)).
>
> I'm a source management guy, I've written a couple of systems.  I live and
> breath diff and diff(1) is not in the slightest way hard.  I wrote my own
> version of SCCS in a way that you could get as many different versions of
> the history as you wanted in one pass.  That's a lot harder than diff(1).
>
> But maybe I don't understand what you think is tricky about diff, you
> may have some insight I'm missing, care to share?

I'm not actually that good a programmer.  Step me through an algo, I can 
probably interpret that as C, BASIC, 6502 ASM or 8086 ASM - but whether I 
can implement it from just an explanation, that's hit or miss.

Frequently I come up with stupid ideas that I think are beyond me, and 
often I'm right.  Once in a while they're not, and I'm able to actually 
implement something.  😜

Stuff like diff or sccs might be easy for some people here - but I've 
spent months wracking my brain on things I think are simpler (6502 CPU 
core for example - which is why for 20 years I used others' cores) and 
been fruitless.

-uso.