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device only works with a 486 boit a slow pentium

wdegroot

Experienced Member
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Sep 19, 2006
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132
I WISH i COULD EDIT THE TITLE
DOES NOT WORK WITH A PENTIUM ONLY A 486


I got a call from someone who tells me that he has a serial semiconductor testing device,
it works with a 486. but not on any pentium.
He argues that a serial port is a serial port.
I countered that a 486 will have a isa bus and a an older Uart chip. ( not sure)
he says this device ( used for semiconductor testing) runs at 9600 baud.
short of finding another 486 what can he do.?
 
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For 486 stuff, he's right--a serial port is just that. I think the 16550 UART came in during the late 286 era. At any rate, it'll be part of a 486 and the Pentium will imitate it. It could well be that the 486 software uses CPU loops for timing and they break down using a Pentium.
 
Umh, I'm not sold on the timing loops, thinking of really slow Pentiums, and really fast 486's, but Pentium systems do have differences.
wdegroot, could you be more specific as to the systems the device worked on, the system the device doesn't work on, oh, and, if you have any details on the device itself, that would be FAB! :)
patscc
 
i've got a handy DOS program called throttle, which (depending on the model/year of the pentium machine*) can make a fast machine appear as a slow machine.
Back in my early testing, I used this program to get an 800MHz P3 to perform closer to a 286 in performance, but you can pick the throttling amount via a small menu.
The throttling itself is done in hardware, so it doesn't interfere with any software. I have gotten reports from people in similar situations who have used this software successfully to slow down machines enough to work with proprietary software that controlled external hardware. I only developed it because I wanted to play games. :)

http://www.oldskool.org/pc/throttle/DOS

This program also (optionally) turns off the L1 cache. Doing that alone might make a pentium machine slow enough that any timing loops work in this software.

* what's interesting here is that you might need a newer/faster machine in order to get the hardware support (ACPI) in order to slow the machine down enough! ACPI didn't really come onto the scene until the mid 1990s.
 
How about SLOWDOWN.COM from PC Magazine's ‘DOS Power Tools’? It was originally written for an AT but I'd bet it's worth a try.
 
I had great results with MOSLO, but looks like throttle is a better tool, nothing against the author of MOSLO, but I do know the work of the author of throttle, and everything is pretty good.
 
the downside for throttle is that it only works on certain chipsets. There is an internal database of a few dozen of them, and i cover all of them that I am aware of that support ACPI throttling. Some oddball chipsets like SIS are less supported than the mainstream intel and via varieties because some chipset manufacturers just don't release their datasheets.

The upside is that it is not a TSR, consumes no memory, and can work in conjunction with moslow, slowdown, etc software for even bigger performance losses.
 
If it is a CPU delay, those "slowdown" programs might not have any effect, due to their granularity. For example, it's not uncommon for a CPU to have been used to delay, say, 50 microseconds when talking to a chip. A CPU slowdown program will do nothing in that case.
 
Other modifications to the Pentium I would try is to disable the cache in the BIOS which most BIOSes permit. I have written code that turned out to be confused once larger caches were available.

I would also move the serial port card from the 486 to the Pentium. If the software and hardware was sold as a package, there is a chance that the developer is checking for the specific serial port card as a crude copy protection method.
 
all useful suggestions.
it is a bit too late tonight to didturb him- he does go to work-
I will email hima at work and suggest eirst they he turn off the cpu cache in bios
If he has a old serial card from 8088 days
he and I go back to 1987, Likely the mouse in the p1 si a ps/2
but he will be running dos I assume.
another thought is to operate from a floppy with older dos as it responds slower than a hard disk I will get specifics on the serial port device..
I and possibly thois man will have some of there old slowdown programs as we both started with 8088 systems
I realize his company is somewhat RETRO
but testing a big box of 387's and similar stuff
requires older tools. the testing stuff we ues when we worked together in 1988 only needed and old pc. it was a long time ago. His daughter born years later is about ready for college. He and his wife have gray hair.
Mine is white.
,
 
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