3 ms·

This was in the early IBM PCs. I know, because I remember I had to replace my 8088 when I got the 8087 floating point coprocessor. I don't recall exactly why th

by _tom_ 4y ago

This was in the early IBM PCs. I know, because I remember I had to replace my 8088 when I got the 8087 floating point coprocessor. I don't recall exactly why this caused it to hit the interrupt bug, but it did.

deleted 4y ago
[deleted]
anyfoo 4y ago
Maybe because IBM connected the 8087's INT output to the 8086's NMI, so the 8087 became a source of NMIs (and with really trivial stuff like underflow/overflow, forced rounding etc., to boot). Even if you could disable the NMI with external circuitry, that workaround quickly becomes untenable, especially when it's not fully synchronous.
- _tom_ 4y ago
  That sounds right. It's been a while.