On Sat, 28 Nov 1998, Jun-Sung Kim wrote:
> Date: Sat, 28 Nov 1998 10:33:42 +0900 (KST)
> From: Jun-Sung Kim <[EMAIL PROTECTED]>
> Reply-To: [EMAIL PROTECTED]
> To: [EMAIL PROTECTED]
> Subject: Re: My MSX project + protect mode
>
>
> Hi,
>
> Lately about the protected mode...
>
> If you want to implement it, minimize it.
> The reason that I like MSX, is the full controllability. MSX is a
> PERSONAL Computer, so all results are responsible to the user.
>
> Well, it may be also good to prevent the important system area
> being crushed in another point of view. Then I suggest that
> just some memory space can be protected optionally. In AHDL style :),
>
> mem_protect = ( A[31] == b"1" ) and not(super);
>
> The simplest way! ( I like always "simple" :)
>
> By the way, did you fix the memory usage(physical/logical memory
> configurations) and the slot pin assignment?
>
> - Jun.
If you want to make a new memory-configuration, and it should be
multitasking (please, make it linux-like and not windows-like), I have a
tip for you that most pc-programmers will not agree with:
Make it possible to use segments. What I mean is you can set some register
outside the cpu on a value rg and if an address ad is asked by the cpu,
the address that is actually read out is ad+mf*rg, where mf is a
multiplying factor, prefferibly smaller than 64 (use a power of 2 of
course, so you don't actually have to multiply). This makes it possible to
load a program into just about any address, and start it from wherever you
want the origin to be. If you would use standard msx-memory configuration
for multitasking, you would have to use at least 16kB for every task, no
matter how small. It's not too hard to implement, but it makes life much
easier for programmers. (I don't know why pc-programmers always say
segments are the worst thing ever invented...)
Bye,
shevek
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