last Intel cpu to run in 8mhz mode?

R

Ron Edward

New Member
Hello,
I am trying to find out what was the last Intel based computer to run in 8mhz mode or Non-turbo or de turbo mode . for now i had to build a old 286/16 system from all kinds or old parts . I have a old CNC circuit boardmaker that only works when you run the 286/16 in non turbo mode which is 8mhz.

so now I figure I could build alittle newer model possibly a Pentium or 486 then run it in non turbo mode.

I tried running a P4 with slow down software and 286 emu software this didn't work.

Thank for any help on this . I seem to recall the Pentiums had a turbo switch

BTW amd also ok , since the 286/16s is a AMD. just wanted to make sure we dont include Motorolas or something ;)
 
I think the 8086 came in 4Mhz, 8Mhz and 10Mhz. The 8088 came in speeds from 4.77Mhz to 8Mhz and the slowest 80286 was 8Mhz. After that you are looking at CPUs that start at 16Mhz minimum.
 
OK...actually, now that I think of it, I do beleive my old comp downstairs is an 8088 at 8MHz(I was thinkin 8086 :P)

They did have 286s at 16MHz, maybe 20. I know because I had at least a 16MHz. An OLD acer.
 
Thank you Guys for the speedy reply.
My 286 being a amd is 16mhz and if you hit the turbo button it will drop down to 8mhz
which is the speed that the CNC board maker likes. another words the turbo light is off so I guess you would call it non-turbo mode .

if i remember 386 and 486 had this Turbo button, and possible the first Pentiums (586?)
what I would like to know is if anyone remembers if the 486 or Pentium will drop down to 8mhz speed when the turbo light is off. (non turbo mode) ?

Thank you for Your Patience and Help. I realize its been along time for everyone playing with machines this old. I know i had to hack my Brain to remember all the jumper settings and Hard drive numbers just to get this 286 pieced to to gether will all kinds of old parts I had in my junk pile. :)

Much appreciated .
 
I think i found the answer . I had to look up the manual for this old Pentium motherboard I have Intel Zappa . if this is true for all Pentium motherboards
it wont go down to 8mhz like 286,386 and 486 CPUs. but to 25mhz :(

here is a clip from manual:
FRONT PANEL CONNECTORS
There is no front panel connector on the baseboard for a Turbo/Deturbo switch. The processor speed can be set either through a parameter in the CMOS Setup Utility, or from the keyboard (<CTL><ALT><+> = Turbo, <CLT><ALT><-> = Deturbo). Changing processor speed from the keyboard may be prohibited by the operating system, or when the processor is in protected mode.
Setting the processor to deturbo (or slow) only slows the processor to the approximate equivalent of a 25 MHz clock rate, not the standard 8 MHz clock rate.

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Again Thank You for the help. hopefully this info will help someone else in the future.
like we all care flying in the gigahertz range now days :)

Take Care
 
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