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QFRESH.DOC
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1991-02-28
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QFRESH.DOC
DRAM, the type of memory used in most PCs, must be refreshed
frequently to keep it from forgeting. The PC is internally
programmed to do this every so often, and uses CPU time when
this is done. The memory refresh rate is set during boot by a
BIOS routine, using a default value contained in the BIOS. The
memory may need less refreshing than is called for by the BIOS
default value. The IBM standard for PCs was overly conservative.
If the rate is changed to less often, which is what QFRESH does,
less time is wasted in refreshing memory. This makes more time
available for processing. However,if you make the refresh rate
too long, you might start to see memory problems.
The following results were obtained on a 386/25 clone with AMI BIOS,
8M of memory, and OS/2 EE 1.3:
A program called CPULOAD constantly graphs the usage of the CPU.
It displays a value of 10% before QFRESH is run. After
the OS/2 version of the program is run, the load value drops to
7-8%. If the DOS version is run instead, the load drops to 6-7%.
Both programs used a refresh rate value of "90".
The DOS version of the program is included if anyone wants to
experiment. The rate value is hardcoded, but it can be changed by
disassembling the program.
Some brands may have decreased the refresh rate, which would explain
why QFRESH has no effect on some machines.
- Walt White and Don Palomaki
Walter White wanted QFRESH as an OS/2 program, and he posted the DOS
machine code, so I "wrapped" it for OS/2, "bound" it so it would work
under either OS/2 or DOS, and posted the result.
It does seem to reprogram the memory refresh timing, and that's all I
will say. If it's good for you, use it! The problem here is that I
use the original Microsoft Bus Mouse, and playing around with this
has some really noticable effects on my mouse tracking!? Also, if you
get "TRAP 02" you have gone too far!
This is a port of QFRESH for OS/2. To use this program, edit your
CONFIG.SYS file and put in a line that says:
IOPL=QFRESH
or
IOPL=YES
and reboot your machine.
To invoke QFRESH, use a line like
[C:\]QFRESH 90
Play with the number until optimal performance is reached (based on
your tolerance of crashing). When you find the right number, just put
the QFRESH statement into your STARTUP.CMD script.
A note on rebuilding:
IOPL requiring apps cannot be bound with recent versions of API.LIB,
that's why D_PORTAC.OBJ is included. If you try to bind with an older
API.LIB, you may want to try NOT binding with D_PORTAC.OBJ. If this
doesn't make any sense, ignore it.
Have fun,
Fred Weigel.