Hi!
> My biggest problem with it, I think, will be that I've been using the Linux
> command line and shells for so long now that I forget most of the dos stuff I
> used to know. But given time, I think most of it will come back to me. I
Of course you can also keep using Linux and run DOS in a window, for
example using DOSEMU which creates some classic virtual hardware for
DOS, such as a SoundBlaster or VGA and VESA compatible graphics. The
CPU is not virtual on 32bit Linux, but sometimes is on 64bit Linux,
depending on kernel and drivers etc. This means that DOS also runs
very fast in DOSEMU :-)
> haven't had the time to actually try those old games yet. But I expect to have
> some fun. Most likely they will run too fast for me to actually play. Even on
> the old Toshiba. {One of the old dos toys I found was called parascan which...
> Well it took about 10 seconds to whip through it all so fast I couldn't read
> the jokes...}
You can try FDAPM SPEEDn where N is a value between 1 and 8: This is
using ACPI to program your mainboard to "freeze" your CPU at regular
intervals and let it run 1/8 to 8/8 of the time. I think I measured
this on one mainboard and found the time slices to be 1/16384 or 32k
seconds each, so 1/8 speed would mean running for 1/16384 second and
then freezing for 7/16384 and so on. This can make your games very
"jumpy", so SPEED2 or SPEED4 or similar might feel smoother... Also,
it is quite possible that your games still run to fast or show some
well-known "runtime error 200" because a delay loop which is meant
to auto-calibrate for your CPU speed cannot loop often enough as a
counter overflows. You can find patches for that online and modify
your game with such a patch tool in that case. Note that more modern
ACPI hardware has even more ways to adjust your speed, including a
way to adjust your CPU clock frequency, but see below for details.
> I don't suppose there is a way to tell FreeDOS to execute something
> more slowly???
There is nothing to tell FreeDOS to execute more slowly, but there
are several ways to tell your hardware to do so. Some examples from
my collection: oldskool.org free open throttle slowDOS, Bret Johnson
has "slowdown" (slowdn310.zip, also open source but the sources are
a separate file to download, free), MOSLO (moslo132.zip).
SLOWDOWN 3.10 by Bret Johnson (now known for his DOS USB drivers)
can be configured to "waste some time" either 18 or 1024 times per
second depending on how you configure it: Your CPU will be *more*
busy, but DOS (-games) will get less things done.
Throttle / slowDOS by Jeff Leyda keeps your CPU busy for multiples
of 1/20 millisecond, 8192 times per second. It can also be used to
switch off the internal PC speaker/beeper 8192 times per second if
you have a game with too annoying soundtrack - both functions are
independent from each other. Can be distributed freely.
MOSLO from hpaa.com is shareware, so if you like it, you buy the
improved version. Not sure if this is still sold / still the case.
The author is "Dr. David Perrell". It does not say much about how
exactly it works, but it lets you slow down DOS by some percentage
and probably wastes the rest of the speed for you :-)
Note that there are two main ways to slow down your system: Freeze
it from time to time and keep it busy with something else. Of course
the latter means extra wasted energy and extra heat. If you run a
virtual system which simulates even the CPU, things will be slower
anyway, because simulating a CPU is slower than just using one, so
running DOS in a completely virtual environment such as VirtualBox
or DOSBOX or VMWare will also run DOS slow enough but it is a pity
to waste the CPU time and energy ;-) If you run DOS inside Linux,
you can often control the CLOCK SPEED of your CPU. For example my
AMD has the settings "on demand", "always fast" or "always slow"
and I can pick a speed from a list in some panel / task bar icon.
As electrical power consumption might be quadratic with speed, in
my example the available speeds are 100%, roughly 4/5, 2/3 and 1/3
for "fast, still fast but lower energy, quite fast and quite slow"
and I guess everything still runs very nicely at 1/3, in particular
when the reason to set 1/3 speed was that I want to play DOS games.
As for the heat, you can run FDAPM APMDOS (even in combination with
FDAPM SPEEDn) to freeze your CPU while DOS is waiting for something
in an obvious way... DOS software should not experience noticeable
slowdown from that, but your CPU will stay cooler and if you run a
virtual machine in Linux, DOS will eat less CPU time from Linux :-)
Regards, Eric :-)
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