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is there any diffrence between an amd and an intel 8088?

oblivion

oblivion

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I'm asking this because I recently bought a Packard Bell pb500 8088 based machine off the forums. This machine has a turbo mode that changes the led from yellow to green when activated. Now this machine came to me with the NEC V20 upgrade. a weird side effect though seems to be that the led will not change color when turbo mode is activated. so for fun since I don't have an Intel 8088 around me I threw in an AMD 8088 just to play around but oddly enough the led still does not change color when turbo mode is activated which leads to my question. is there a difference between the intel and amd chip that somehow confuses the motherboard about the led color change? unfortunately I don't have an Intel chip to check if that's really what the issue was but i thought it was an interesting question to ask wither way.
 
As far as I know there are no detectable differences between Intel and AMD 8088... Moreover as far as I know AMD used Intel masks to manufacture 8088/8086 (according to some sources AMD, Harris/MHS, and Siemens had Intel masks while NEC and other Japanese companies had to reverse engineer 8088).

Now to the turbo mode - there is no special support for turbo mode in the 8088 or V20 CPU, other than the CPU just needs to be fast enough to support the turbo frequency. CPU clock generation happens outside of CPU. Standard approach for implementing the turbo mode in XT-class machines is to switch the frequency on the EFI input of 8284 clock generator. Usually there is a glitch-less clock switching multiplexer that is used to select either 14.31818 MHz (normal) or the turbo clock. Depending on motherboard this multiplexer can be controlled either by an external switch (turbo button) or software (normally through an unused bit of 8255 port B, e.g. bit #2), in some cases both can be used.

Not sure how turbo LED is controlled in your case. In some computers turbo LED is simply connected directly to the turbo switch, so LED won't work if turbo turned on using software.

By the way are you sure that what you have is the turbo LED at all? Check its polarity... or test it connecting to a different LED header (e.g. instead of the power LED).
 
That Packard Bell used to be mine. When I first got it, the power indicator LED did change color when switching from normal (4.77 MHz) to turbo (9.54 MHz) mode using Ctrl-Alt-+ on the keyboard. Somewhere along the line, the LED stopped changing color even though turbo mode still worked fine (system info / benchmark programs still report it as running at 9.54 MHz). I thought that was due to me replacing the 8088 with a NEC V20 chip, but maybe not. So who knows, maybe the second color in the LED simply burned out!
 
So the light stays the same color, or goes out when turbo is activated? You would think the light would go out if it was burned out. Unless both led colors illuminated at the same time?
 
I remember AMD used copied Microcode of Intel till 80386 was released.
After 80486, AMD should change the Microcode.

Of course AMD 8088 is different from Intel.
But each compatibility must be nearly 100% if the microcode is same as Intel.
 
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