Problems Resulting From Upgrading an 8088 CPU to a V20 CPU
This upgrade results in the BIOS executing slightly faster than what the BIOS was written for.
On some computers, that is not a problem.
On other computers, subtle timing issues result.
My early IBM 5160 (first BIOS revision) contains the long version of the AST SixPakPlus card.
If I substitute the 8088 CPU with a V20, I discover that the 5160 will no longer start (power supply runs, but motherboard appears 'dead').
Put the 8088 back in, and the 5160 starts.
So, there is one example of a V20 upgrade causing a problem.
By the way, I discovered that I could use the V20 only if I did one of the following:
1. Remove SixPakPlus card, or
2. Upgrade BIOS to the final revision. [The POST in this revision waits longer before RAM is used.]
The cause of my problem appears to be described in the document at here.