Re: [Tack-devel] [Spam] MINIX 1.5 and ACK

[David G. <dg...@co...>]

I had a play with the code. The Z8000 code generator builds and runs and
generates code, but of course I have no idea whether it generates working
code. The assembler does not; in common with a lot of the very old
architectures it's runs in assembler/linker mode, where it generates
non-relocatable binaries rather than .o files which can be linked together.
This would need fixing. (I've done it before and it's not a lot of work.)

Of course, it still needs a plat with a syscall library, startup code etc
before it'll do anything useful.

What OS does the M20 run?

On Fri, 22 Mar 2019, 18:54 Christian Groessler, <ch...@gr...> wrote:

> Not in the way the 8086 did with its segment registers.
>
> But the CPU has output pins which indicate if a memory access is an
> instruction fetch or data access. And the M20 implements (at least) one
> segment where this is used. So address X points to different physical
> memory, depending on whether it's an instruction or data access.
>
> regards,
> chris
>
>
> On 3/22/19 5:48 PM, David Given wrote:
>
> Did the Z8000 do split I/D? The 8086 cheated because both code *and* data
> got different 64kB address spaces, so you could have 64kB of code and still
> have 64kB of data. I don't think you could fit the compiler into a single
> 64kB space.
>
> There is a Z8000 code generator in the ACK but it's based on the old _old_
> code generator model and was last touched in the 1990s, so I don't know
> whether it works or what the code quality is like. Plus, of course, then
> you need to make it fit.
>
>
> On Fri, 22 Mar 2019 at 14:05 Christian Groessler <ch...@gr...>
> wrote:
>
>> Hi,
>>
>> On 3/11/19 8:13 AM, Jacobs, C.J.H. via Tack-devel wrote:
>> > Good question! I survived, and I produced those binaries back then. But
>> this was a very long time ago,
>> > and my memory has never been any good... nor are my archiving skills...
>> When I find some time, I’ll
>> > see if I can do some digging. From what I remember, the only real
>> problem was getting the compiler front-end
>> > to fit in 64K instruction space and 64K data space. For that, we took
>> out the C preprocessor (which was/is built-in
>> > into the C frontend) and made it a separate pass, and we also took out
>> the floating-point library. Other than that,
>> > I don’t remember exactly, but I think it was just a little bit of
>> tweaking.
>>
>>
>> It would be great if you would find this version.
>>
>> I'm toying with the idea to port Minix 1.5 to the Olivetti M20, a Z8000
>> based computer. The Z8000 has 64K segments as well.
>>
>> regards,
>> chris
>>
>>
>>
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>