OT microsoft rant

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That is as I remember it.


Yes. But when startting a DOS program below 640K, then it starts in
full 16bit gorgeousness. So as DOS is, 16bit. ?

Real Mode is not more bad than protected mode, it`s only 16bit.
Click to expand...
True, but you have the 1MB memory limitation.
hmmmm, I am wondering what that is about 286 code. Could a 8086 run 286
code? Are there even differencies? Protected Mode??

Regarding to your post it means to me, that also a 8086 could address
16MB?
Not to forget the 8087 and Turbo-Button ..etc ;-)
Click to expand...
No, a '286 had code available which the 8088/8086 could not run. The
8088/8086 did not have Protected Mode. The only way that an 8088/8086
could use extra memory was by using add-on chips which enabled the
switching of RAM into a 4KB slot. This process was called either
extended or expanded RAM. I think "expanded" was the correct title.
When the 80286 came on the market the other term was used for its
memory management system.

The 8087 was only a math co-processor and there were matching 80287,
80387 and 80487 chips as well. The 80486DX had the maths co-processor
built in but the 80486SX did not and needed the 80487 for math
intensive work. It would work with the 80387 also.

All programs written for DOS needed to be usable on an 8088/8086 so
the '286 extensions were not used in compilation until Himem.sys and
EMM became part of DOS with the infamous MS-DOS V4. Even then it took
some time before it became commonplace around the time of DOS 5.

The turbo button was a kludge to slow the processor down in order that
games, which counted processor cycles for timing, would not be too
fast.
 
Daniel said:
Gary R. Schmidt wrote:

Daniel Mandic wrote:
[SNIP]
As I supposed. When there is a 286 version, a 8086 version cannot be
far away :-). The same CPU. The 286 can address more memory.
Click to expand...

Wrong. Well, right, but not in the way you think it is.

The 80286 came well after the 8086.

The sequence is something like this:
8088 - 8086 - 80186 - 80286 - 80386 ...

The '186 was an interesting device, some real advances over the 8086,
but hamstrung in many ways.
Click to expand...




Yes, of course. The 286 can access 16MB of (XMS??) RAM. So the
Click to expand...
No, it's just memory. The XMS (eXtended Memory Standard) was a way to
trick a real-mode '286 into being a protected-mode one for a while.
Sort of.
programes can be more extensive. But the 286 holds also some CPU
extensions, AFAIK. But the 386 (Compaq) left that all behind. The
IBM-PC jumped from 8 to 32 bit, IMO. Where the HC-community already had
32bit-cored CPU´s, in times of 8088/8086/-AT286 and some ultra-fanatics
with 6-7000 bucks 386/16 386/25 machines.... intel of course.

186. Is that not built-in, in Airplanes for the Black-box? :-)

I would say, a 286 instruction-code outfitted 8086 !?
Click to expand...
Wrong. Go read the specs on the '186.

The major difference in Protected Mode was what the "Segment Registers" do.

Boring stuff for non-programmers follows:
In Real Mode, an address register could address 16-bits (65536 bytes) of
memory, the segment register added another (potential) 16-bits. But.
It didn't quite work like that, there was some overlap between the
segment register and the offset register, so that you could only get at
1 Megabyte.

In Protected Mode, the segment register does not contain an address, it
contains a segment selector, so that you can address all 16 Megabytes.

This was also true in the 80386, which has 32-bit offset registers and
16-bit segment registers, so could address 48-bits in Protected Mode,
but, IIRC, only 40-bits in its real mode.

Daniel - go spend some time reading the specs of these chips on the
Intel site, it will do you good, in the long run. Why? Because there
several interesting advantages to segmented architectures, as well as
drawbacks, people have gotten so used to the flat 32-bit model that
anyone who knows about the underlying architecture has an advantage.

Cheers,
Gary B-)
 
Jim said:
While telling old war stories...

Your mention of the Turbo-Button reminded me of the outfit(s) that
produced a "speed test demo" program for computer shows. As I recall,
the test altered the TOD clock interrupt routine to make the machines
appear to run much faster than a reference machine without said TOD
clock modification.


-Jim
Click to expand...



war...? huh?

You mean it was so much war for such computer.
They had its place as today. :-)

I am using that stuff (mostly games) today. Below 286, and very good
software. Everything working on a hyper IBM-PC (I think 686). Thanks to
the compatibility line of iNTEL and Microsoft.
Especially the extended Games (protected mode) are very nice (quite
faster :-)) with today PC's :)




Best Regards,

Daniel Mandic
 
David wrote:

d Turbo-Button ..etc ;-)
No, a '286 had code available which the 8088/8086 could not run. The
8088/8086 did not have Protected Mode. The only way that an 8088/8086
could use extra memory was by using add-on chips which enabled the
switching of RAM into a 4KB slot. This process was called either
extended or expanded RAM. I think "expanded" was the correct title.
When the 80286 came on the market the other term was used for its
memory management system.
Click to expand...


Expanded = Hardware Extended = Software

You enlightened my memories.

I think DOS can reach that ram-area again, with the emm386.exe and
usage of the CPU-MMU. Otherwise there are nice programmings possible,
when using the EMS RAM. E.g. Tempest 2000 'Demo' for DOS and EMS (about
2000K!) on. Really a game which can compare to arcade-chipset computer,
IMO. Brilliant FM Sound!!




Best Regards,

Daniel Mandic
 
Gary said:
Daniel - go spend some time reading the specs of these chips on the
Intel site, it will do you good, in the long run. Why? Because
there several interesting advantages to segmented architectures, as
well as drawbacks, people have gotten so used to the flat 32-bit
model that anyone who knows about the underlying architecture has an
advantage.

Cheers,
Gary B-)
Click to expand...



Thanks for that. I am more than outfilled studying a CPU I had, at
times before 286 and co.

Yes, it´s interesting to know about the Pentium predecessors. But I
(low entry coder) would be overwhelmed, encumbering myself with 386 or
586 coding, too.




Best Regards,

Daniel Mandic
 
But Xenix _never_ ran on the 8088, it needed an 80286 (or a PDP-11).

Another newbie.

Xenix DID run in a 8088. SCO introduced its first version of Xenix
named SCO Xenix System V for the Intel 8086 and 8088 in 1983. So many
newbies that know no shit...
 
Another newbie.

Xenix DID run in a 8088. SCO introduced its first version of Xenix
named SCO Xenix System V for the Intel 8086 and 8088 in 1983. So many
newbies that know no shit...
Click to expand...
I've already admitted to my error - well, not so much an error as an
absence of knowledge - due to me working with pretty much only with
PDP-11s and VAXen and so forth until 1986.

I didn't even _use_ an 8086 (might have been an 8088, it was an Apricot)
until late in 1985.

Thinking about it, although I had used 4004s and so forth as
micro-controllers, I don't think I used an Intel chip as a general
purpose device until then.

It was quite a shock, going from the nice flat memory space of the
32-bit CPUs, or the well organised 16-bit ones, to the harsh and
needlessly difficult world of the x86 architecture and MS/PC-DOS. (I
never found an overlay linker in the x86 world that worked as well or as
easily as the one under RSX-11 on the PDP-11).

So when were you a "newbie", Ulf?

Cheers,
Gary B-)
 
I've already admitted to my error - well, not so much an error as an
absence of knowledge - due to me working with pretty much only with
PDP-11s and VAXen and so forth until 1986.

I didn't even _use_ an 8086 (might have been an 8088, it was an Apricot)
until late in 1985.
Click to expand...
Wasn't the Apricot an Apple rip-off?
Thinking about it, although I had used 4004s and so forth as
micro-controllers, I don't think I used an Intel chip as a general
purpose device until then.

It was quite a shock, going from the nice flat memory space of the
32-bit CPUs, or the well organised 16-bit ones, to the harsh and
needlessly difficult world of the x86 architecture and MS/PC-DOS. (I
never found an overlay linker in the x86 world that worked as well or as
easily as the one under RSX-11 on the PDP-11).

So when were you a "newbie", Ulf?

Cheers,
Gary B-)
Click to expand...
LOL.
 
Another newbie.

Xenix DID run in a 8088. SCO introduced its first version of Xenix
named SCO Xenix System V for the Intel 8086 and 8088 in 1983. So many
newbies that know no shit...
Click to expand...
Ulf, please try to pay attention.

1) This has already been discussed (w/o disparaging remarks btw)
2) Gary, whose quote you cite, is far from a 'newbie.'

-Craig
 
David said:
Wasn't the Apricot an Apple rip-off?
Click to expand...

Speaking of Apples...

SCO worked like a hampster on crack to get a Xenix ported to Apple's
Lisa, only to have Apple pull the plug in short order. Apparently,
Larry was pissed off for a long long time afterwards.

-Craig
 
David wrote:
[SNIP}
Wasn't the Apricot an Apple rip-off?
Click to expand...
No. They tried to do the "we design our boxes better" thing, though.

There was also the Hitachi Peach!

Not that I ever used one, I just remember the name.

It's a pity that no-one came out and admitted that their box was a Lemon!

Cheers,
Gary B-)
 
Speaking of Apples...

SCO worked like a hampster on crack to get a Xenix ported to Apple's
Lisa, only to have Apple pull the plug in short order. Apparently,
Larry was pissed off for a long long time afterwards.

-Craig
Click to expand...

I don't blame him but apparently, besides being vastly overpriced even
for Apple, the Lisa had a bad reputation. In my opinion Apple did the
right thing in pulling the plug. The Macintosh was a vastly superior
machine and SCO had probably done most of the work needed for a port.
 
David wrote:
[SNIP}
Wasn't the Apricot an Apple rip-off?
Click to expand...
No. They tried to do the "we design our boxes better" thing, though.
Click to expand...
A la Amstrad.
There was also the Hitachi Peach!

Not that I ever used one, I just remember the name.
Click to expand...
I've thrown all my old magazines so I can't check but I seem to
remember that name as well.
It's a pity that no-one came out and admitted that their box was a Lemon!

Cheers,
Gary B-)
Click to expand...

There were many Lemons that didn't make the cut.
 
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