[Simh] Simh Digest, Vol 169, Issue 53

[Larry Baker]

Rob,

savaii:Earthworm baker$ brew list sdl2
Error: No such keg: /usr/local/Cellar/sdl2
savaii:Earthworm baker$ brew list sdl
Error: No such keg: /usr/local/Cellar/sdl
savaii:Earthworm baker$ brew list libsdl
Error: No such keg: /usr/local/Cellar/libsdl
savaii:Earthworm baker$ brew list libsdl2
Error: No such keg: /usr/local/Cellar/libsdl2
savaii:Earthworm baker$ find /usr -name libsdl\*
find: /usr/sbin/authserver: Permission denied

As I recall, I did not have to change anything in the most recent SIMH build procedure on a Mac.

Larry Baker
US Geological Survey
650-329-5608

Date: Fri, 16 Feb 2018 20:23:22 -0000
Subject: [Simh] Installing SDL2 on Mac To Build SIMH
Content-Type: text/plain; charset="utf-8"
I don't have a Mac but I need someone to be able to build SIMH on his Mac
https://www.libsdl.org/download-2.0.php <https://www.libsdl.org/download-2.0.php>
I don't understand if you need runtime or dev libraries, I have tried
opening both dmg files with 7Zip and I can't find anything in either that
looks like a libsdl2.a file. What am I looking for and where would I put the
file to be able to link it? Compile already works.
Regards
Rob

[Clem Cole]

Strange:

% brew list sdl2
/usr/local/Cellar/sdl2/2.0.7/bin/sdl2-config
/usr/local/Cellar/sdl2/2.0.7/include/SDL2/ (72 files)
/usr/local/Cellar/sdl2/2.0.7/lib/libSDL2-2.0.0.dylib
/usr/local/Cellar/sdl2/2.0.7/lib/cmake/SDL2/sdl2-config.cmake
/usr/local/Cellar/sdl2/2.0.7/lib/pkgconfig/sdl2.pc
/usr/local/Cellar/sdl2/2.0.7/lib/ (4 other files)
/usr/local/Cellar/sdl2/2.0.7/share/aclocal/sdl2.m4
[ctcole-mac07:~] ctcole% brew --version
Homebrew 1.5.2-3-g0f44937
Homebrew/homebrew-core (git revision f4db43; last commit 2018-01-25)
ᐧ

Rob,
I don't understand why you need sdl2. I recently built SIMH on my El
Capitan Mac at work and my Sierra Mac at home and had no need to install
savaii:Earthworm baker$ brew list sdl2
Error: No such keg: /usr/local/Cellar/sdl2
savaii:Earthworm baker$ brew list sdl
Error: No such keg: /usr/local/Cellar/sdl
savaii:Earthworm baker$ brew list libsdl
Error: No such keg: /usr/local/Cellar/libsdl
savaii:Earthworm baker$ brew list libsdl2
Error: No such keg: /usr/local/Cellar/libsdl2
savaii:Earthworm baker$ find /usr -name libsdl\*
find: /usr/sbin/authserver: Permission denied
As I recall, I did not have to change anything in the most recent SIMH
build procedure on a Mac.
Larry Baker
US Geological Survey
650-329-5608 <(650)%20329-5608>
Date: Fri, 16 Feb 2018 20:23:22 -0000
Subject: [Simh] Installing SDL2 on Mac To Build SIMH
Content-Type: text/plain; charset="utf-8"
I don't have a Mac but I need someone to be able to build SIMH on his Mac
https://www.libsdl.org/download-2.0.php
I don't understand if you need runtime or dev libraries, I have tried
opening both dmg files with 7Zip and I can't find anything in either that
looks like a libsdl2.a file. What am I looking for and where would I put the
file to be able to link it? Compile already works.
Regards
Rob
_______________________________________________
Simh mailing list
http://mailman.trailing-edge.com/mailman/listinfo/simh

[Rob Jarratt]

I need SDL2 because the emulator I am writing needs it for audio and I am
also doing a graphical console.



Regards



Rob



From: Larry Baker [mailto:***@usgs.gov]
Sent: 16 February 2018 20:58
To: ***@ntlworld.com
Cc: SIMH <***@trailing-edge.com>
Subject: Re: Simh Digest, Vol 169, Issue 53



Rob,



I don't understand why you need sdl2. I recently built SIMH on my El
Capitan Mac at work and my Sierra Mac at home and had no need to install
sdl2. In fact, my brew does not even know about it:



savaii:Earthworm baker$ brew list sdl2

Error: No such keg: /usr/local/Cellar/sdl2





savaii:Earthworm baker$ brew list sdl

Error: No such keg: /usr/local/Cellar/sdl





savaii:Earthworm baker$ brew list libsdl

Error: No such keg: /usr/local/Cellar/libsdl





savaii:Earthworm baker$ brew list libsdl2

Error: No such keg: /usr/local/Cellar/libsdl2





savaii:Earthworm baker$ find /usr -name libsdl\*

find: /usr/sbin/authserver: Permission denied



As I recall, I did not have to change anything in the most recent SIMH build
procedure on a Mac.



Larry Baker
US Geological Survey
650-329-5608
***@usgs.gov <mailto:***@usgs.gov>







On 16 Feb 2018, at 12:32:08 PM, simh-***@trailing-edge.com
<mailto:simh-***@trailing-edge.com> wrote:



Date: Fri, 16 Feb 2018 20:23:22 -0000
From: "Rob Jarratt" < <mailto:***@ntlworld.com>
***@ntlworld.com>
To: < <mailto:***@trailing-edge.com> ***@trailing-edge.com>
Subject: [Simh] Installing SDL2 on Mac To Build SIMH
Message-ID: < <mailto:004b01d3a763$fdcfc7d0$f96f5770$@ntlworld.com>
004b01d3a763$fdcfc7d0$f96f5770$@ntlworld.com>
Content-Type: text/plain; charset="utf-8"

I don't have a Mac but I need someone to be able to build SIMH on his Mac
and be able to link SDL2. I have looked at this page:
<https://www.libsdl.org/download-2.0.php>
https://www.libsdl.org/download-2.0.php



I don't understand if you need runtime or dev libraries, I have tried
opening both dmg files with 7Zip and I can't find anything in either that
looks like a libsdl2.a file. What am I looking for and where would I put the
file to be able to link it? Compile already works.



Regards



Rob

[Larry Baker]

Sorry Clem and Bob,

I think you are mixing apples and oranges and adding confusion with your use of VM to describe two different things. Relying on my own recollections of the early days of virtual memory... What the PDP-11 does is memory mapping with an MMU. Virtual memory is a concept, described in a seminal ACM article by Peter Denning (https://en.wikipedia.org/wiki/Peter_J._Denning <https://en.wikipedia.org/wiki/Peter_J._Denning>). Memory mapping and virtual memory both require that whatever code or data that a program is permitted to access must actually be resident in memory. While there is hardware in an MMU to trap unmapped memory accesses, in a true VM architecture there is no aliasing of memory addresses to multiple code or data objects. Whether overlaying is done by overwriting already mapped program memory from storage or by remapping program address space to another memory block, the same memory addresses are reused to reference different objects. The MMU cannot tell whether the object being referenced is the "correct" object intended by the programmer. Other methods must be employed, such as an indirect "entry-point table" that can perform the MMU remapping on-the fly. In a true VM architecture, different objects can be distinguished by their program addresses. This is a key distinction between memory mapping and virtual memory.

That's my 2¢.

Respectfully,

Larry Baker
US Geological Survey
650-329-5608

Date: Fri, 16 Feb 2018 14:51:27 -0500
Subject: Re: [Simh] pdp11 i/o addressing
Content-Type: text/plain; charset="utf-8"
curmudgeon warning below.....
Date: Fri, 16 Feb 2018 20:23:05 +0000
Subject: Re: [Simh] pdp11 i/o addressing
Content-Type: text/plain; charset=ISO-8859-1
When I teach virtual memory, I start by talking about the 'old days'
and overlays. I remember Overlay Description Language on the PDP-11!

[Clem Cole]

Post by Larry Baker
In a true VM architecture, different objects can be distinguished by their
program addresses. This is a key distinction between memory mapping and
virtual memory

​Larry - I 100-% agree with you. My point was that from a programmer's
standpoint, I can (and have as Tim describes, I used those maps too),
remember pushing past the address space limits on our PDP-8 which was were
I first messed with manual overlays.​ But we had real VM (as described by
Denning) in the IBM 360/67 running TSS at the same time. Our first
PDP-10's did not and of course the 11's did not either.

So I just remind folks that programming in a memory constrained environment
can be done by an application program to get around the limits of the
number of address bits that the HW supplies. VM is supported by the OS,
without application programmer intervention - which certainly makes it
desirable. As Tim pointed 32 bits was both 'not enough' and the memory
scheme could be abused. It's not a universal solution to all memory
issues. It is handy, but we lost something too.

I was suggesting that not enough programmers are taught about overlays.
Frankly they should be before they learn about VM; IMO. Learning how your
program lays out in memory and how it is going to perform, what it is call
graph look like etc... these are skills that you acquired naturally in
the old days and much hard to understand, but less realize why they are
important.

BTW: a similar lost art of that of mathematical interpolation and
'significant digits.' I'm the last of a breed of engineer that learned on
a slide rule too; which is where you quickly get an understanding of those
two concepts. That said, just as I'd rather not go back to having to do
manual overlays; I did love my TI-50 (first calculator that have
transcendental functions) when I got it in the early 1970s.
:-)

Clem
ᐧ

[Johnny Billquist]

Post by Larry Baker
Sorry Clem and Bob,
I think you are mixing apples and oranges and adding confusion with your
use of VM to describe two different things.

Yes. We have a conflation of two different things. A rather common
mixup, unfortunately. Even more, though, while your comments below are
accurate, overlays are commonly not done through the MMU at all, so that
is yet another aspect. (That said, under RSX, there is the option of
having overlay mapping done through the MMU, which is faster, but
potentially waste a lot of memory space.)

Johnny

Post by Larry Baker
 Relying on my own
recollections of the early days of virtual memory...  What the PDP-11
does is memory mapping with an MMU.  Virtual memory is a concept,
described in a seminal ACM article by Peter Denning
(https://en.wikipedia.org/wiki/Peter_J._Denning).  Memory mapping and
virtual memory both require that whatever code or data that a program is
permitted to access must actually be resident in memory.  While there is
hardware in an MMU to trap unmapped memory accesses, in a true VM
architecture there is no aliasing of memory addresses to multiple code
or data objects.  Whether overlaying is done by overwriting already
mapped program memory from storage or by remapping program address space
to another memory block, the same memory addresses are reused to
reference different objects.  The MMU cannot tell whether the object
being referenced is the "correct" object intended by the programmer.
 Other methods must be employed, such as an indirect "entry-point
table" that can perform the MMU remapping on-the fly.  In a true VM
architecture, different objects can be distinguished by their program
addresses.  This is a key distinction between memory mapping and virtual
memory.
That's my 2¢.
Respectfully,
Larry Baker
US Geological Survey
650-329-5608

Date: Fri, 16 Feb 2018 14:51:27 -0500
Subject: Re: [Simh] pdp11 i/o addressing
Content-Type: text/plain; charset="utf-8"
curmudgeon warning below.....
Date: Fri, 16 Feb 2018 20:23:05 +0000
Subject: Re: [Simh] pdp11 i/o addressing
Content-Type: text/plain; charset=ISO-8859-1
When I teach virtual memory, I start by talking about the 'old days'
and overlays. I remember Overlay Description Language on the PDP-11!

_______________________________________________
Simh mailing list
http://mailman.trailing-edge.com/mailman/listinfo/simh