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DOS CPU speed tester?

M

Mike Chambers

Veteran Member
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Sep 2, 2006
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is there a good and simple utility out there that i can run on an 8088 to verify the CPU speed? i'm trying to get the turbo 8 MHz mode working on a motherboard and i want to verify.
 
thanks for the link Ole Juul! i downloaded cputest.zip ..... i really hope it's inaccurate. here's the output when i run it on one of my 8088s.

Elapsed time in second ... 17.25
Detected 8088 CPU at equivalent of ... 4.77 mhz
Effective clock speed is ... 3.37 mhz
Estimate MIPS at ... 0.16
Times faster than original 4.77 mhz PC ... 0.71
Click to expand...

if that's accurate i think my motherboard has problems. :(

i'll try another program and see what happens.
 
I don't suppose you have access to an oscilloscope? Nothing like testing hardware with hardware!
 
cosam said:
I don't suppose you have access to an oscilloscope? Nothing like testing hardware with hardware!
Click to expand...

nope, unfortunately i don't but it seems like it's an issue with the prog. i get the exact same result on both my turbo board and my BMI XT clone. so that's good. :)
 
Mike,
The turbo mode is definitely not enabled. You are running at the slowest rate possible, PC with 4.77 MHz clock and with a wait state or two for slow memory. I did not know that any 8088 machines had 'turbo mode' capability. I thought that all started with 286 machines.
 
I'm no pro, but any "turbo" switch that I've evern encountered was actually for slowing down the CPU. I think they just labeled them that way around because it looked good. :p I always thought it was kinda funny but perhaps that just a certain generation.
 
surely your QB's good enough to read the RTC, do a for-next loop 100000 times, read the RTC again and subtract the 2 readings,
then do it again with the turbo on.

if the two times are in the ratio 8 to 4.77 then you're working!

I did once have a turbo clock jumper fall off a motherboard, the PC worked, but incredibly slowly, presumably on an clock induced from elsewhere into the open circuit line. It was the machine I then went on to build a varispeed clock for, as I knew where to put the signal in. That got me through the "space skimmer" bit in Spacequest 1!
 
nige the hippy: I did once have a turbo clock jumper fall off a motherboard, the PC worked, but incredibly slowly
Click to expand...
I guess there is something I don't get about this turbo thing. :) On 386/486 boards if you put the turbo jumper (or switch) on it goes slowly. What am I not understanding here? Were there some boards that actually had some serious overdrive? It seems to me that a (eg) 40Mhz board goes at 40Mhz and if you want to go faster by any significant amount you have to get a faster CPU. Your only realistic speed choice is to go slower. My understanding is that some unscrupulous manufactures put a switch (or jumper) on the clock and labeled it backwards so as to fool unsuspecting customers. Correct me if I am wrong.
 
One interpretation of the button for the 'turbo mode' is that it is not to make the machine to go faster, but to slow it down for compatibility purposes. Most people would normally run the machine at full speed, unless they were playing a game that was too fast.
 
mbbrutman said:
One interpretation of the button for the 'turbo mode' is that it is not to make the machine to go faster, but to slow it down for compatibility purposes. Most people would normally run the machine at full speed, unless they were playing a game that was too fast.
Click to expand...
Thanks for the reality check Mike. :) That's how I understood it too, but I was beginning to wonder if there actually was such a thing as "turbo" - I don't think there is.
 
Just to clear up, the jumper that fell off was actually feeding a clock in rather than being just a switch (for different speed CPUs)

I never thought about the nature of turbo mode, I just always used machines with a turbo switch, in whatever was the fastest mode (unless otherwise required) I always just assumed that turbo was fast, and didn't take much note of whether the switch was pressed in, or the light on or whatever.
 
In 1984 I built my first clone XT, it had a turbo motherboard that could run at 8 Mhz or 4.77 Mhz. As I recall, the early clone bios could not format disks at 8 Mhz so I normally ran the computer at 8 Mhz but switched to 4.77 Mhz to format disks. Later the bios was updated and supported formatting at 8 Mhz so I could run 100% of the time at 8 Mhz. There was a very definite speed improvement difference between 4.77 and 8 Mhz.
 
The turbo switch also threw me off when I was young. I think the only thing I noticed was in QB it would do a simple 10 ? "I'm cool": goto 10 quicker in turbo mode although everything else was slower? .. it's been a long time but from what I recall that's how it was. It wasn't until I stopped eating school lunches long enough to save up and get a pretty sweet Toshiba luggable/laptop from the neighbors garage sale that was a 386 and had high and low mode for it's processor. (ctrl+alt+h or l) that I started to realize the use of it.
 
I've got PC doctor that will run on my Philips NMS9100 (P3105) so should work on most other systems. It has a whole load of other functions too.
Anyone want it ?
 
SunDown79 said:
I've got PC doctor that will run on my Philips NMS9100 (P3105) so should work on most other systems. It has a whole load of other functions too.
Anyone want it ?
Click to expand...

I do believe that I could use it.Email or hard copy?Thanks!
cgrape2
 
Try this little program. It shows cpu speed and video speed. ;) The main program SST.EXE is only 52K. Hope this helps.
 

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