Info on 386 to 486 Upgrade cpus please

Hi all

I have a few Amstrad Mega PC's. One of them upgraded to 486 50mhz using a cyrix chip (Same as the SRX chip) I recently installed a new HDD and managed to get the cache and chips working using software supplied by a fellow Amibayer

Im looking for information what other chips could be used to upgrade a 386 sx 25. I dont mind if they have a large heatsink on top as I think the mega pc floppy/hdd cradle could be modified to accommodate.

I have heard of the IBM Blue lightning and apparently it is the fastest upgrade chip but dont know if this would work on an SX as some chips are particular to 386 DX models etc.

Any help would be appreciated.:thumbsup:

I have investigated the same in the past... there are some upgrade chips with IBM's "486slc" (in quotes bevause they are vastly superior to the cyrix ones since IBM ultra-finetuned the architecture) BUT they are almost impossible to find. I never saw one for sale and the only IBM 486slc cpus I have seen are soldered at IBM's motherboards...
Basically we are stuck with the 486slc2 (and similar) upgrades...
If you ever manage to get an IBM upgrade it will work just like the cyrix one: by disabling the soldered cpu and using double/triple internal speed.
Personally I gave up searching some ~2 years ago...

I have a Cyrix486SLC2@50MHz CPU. On my A2386 bridgeboard, Norton Sysinfo rates it as powerful as a 486DX33. About 4 times better than the original 386sx@25MHz. The 1KB cache needs to be activated by software in autoexec.bat. However it does run hot. The advantage is that i have been able to use a Math&Co 387FPU with it.
There are also some 486SLC3 able to run at 75MHz but i have never found one.
If you are willing to solder to install such a CPU, i have a new Texas Instrument 486SLC@25MHz available for swap. It has a 1KB cache similar to the Cyrix one.
As for the IBM Blue Lightning, several CPUs bear that name. Some of them are 486SLC3 CPU with a 8KB cache: that's why they are better than the Cyrix/Texas. I am unsure they have been sold as clip-on upgrade, but they can be found soldered on some IBM mobo.

Could this CPU be used for the upgrade? https://en.wikipedia.org/wiki/Intel_80486_OverDrive

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Originally Posted by alenppc

Could this CPU be used for the upgrade? https://en.wikipedia.org/wiki/Intel_80486_OverDrive

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No, those are not compatible with the 386sx class.

I have the Cyrix 486 DX2 50 with 1k cache and have the software thank to Keropi.

Has anyone got a picture of the IBM SLC chip so I can see what I am looking for.:thumbsup: (The only ones I can see are the normal processors) The clip on types must look similiar to mine?

they look like 386sx chips:

http://lh6.ggpht.com/_CzHY0sEvu6A/SY...-upgrade-L.jpg

also check this: http://redhill.net.au/c/c-4.html#slc2 and since you are there check the rest of the stuff on the article, it holds some GREAT info! index is here: http://redhill.net.au/ig.html

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Originally Posted by limboy777

I have the Cyrix 486 DX2 50 with 1k cache and have the software thank to Keropi.

Has anyone got a picture of the IBM SLC chip so I can see what I am looking for.:thumbsup: (The only ones I can see are the normal processors) The clip on types must look similiar to mine?

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Hi limboy777,
try this site CPU World --->Link

@lopos2000

these are 387 fpu chips , not 486slc cpu ones

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Originally Posted by keropi

@lopos2000

these are 387 fpu chips , not 486slc cpu ones

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I know. You have to scroll down a bit to see the 487 one's. Just wanted to show him the link to all Cyrix CPU's.:lol: