kim@amdahl.amdahl.com (Kim DeVaughn) (10/04/87)
[ For all you do ... this line's for you ... ]
Yeah, I know ... the ink is hardly dry on the shipping containers, but ...
Has anyone tried replacing the 8088 in the Bridge card with a NEC V20
chip? If so, have you run into any problems?
For those of you that don't know, the NEC V20 is a replacement chip for
the 8088 (and the V30 is a replacement for an 8086). It is electrically,
logically, and mechanically compatible with the Intel parts, but provides
improved performance without any other changes (many instructions require
fewer cycles to execute). Also, the NEC parts include the 80186 instructions,
several NEC exclusive instructions, and an 8080/8085 compatibility mode.
There are some s/w packages on the market that take advantage of the 8085
mode to allow one to run CP/M on a PClone.
The compatibility is *very* good; I've had a V30 in my MS-DOS machine for a
couple years, and the only thing that has been a problem are some braindead
copy-protected crap, and some stuff that used s/w timing loops. The increase
in performance is definitely noticeable ... subjectively about 15% for string
intensive applications like editors, a little more for integer intensive code,
and nothing for floating-point programs.
Not a bad deal for the $10-$15 that a V20 costs these days!
Should anyone want to try this ... I would suggest getting the 8 MHz V20
part, due to a slight difference in the required clock duty-cycle that the
5 MHz part wants to see.
Anyone at CBM Engineering try one of these puppies out yet?
/kim
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