9 Dec
2005
9 Dec
'05
12:35 p.m.
Subject: Re: Legacy apps in Windows/OS X was Re: Old MS-DOS & Win Software
From: "Chuck Guzis" <cclist at sydex.com>
Date: Thu, 08 Dec 2005 21:59:46 -0800
To: cctalk at classiccmp.org
On 12/8/2005 at 9:49 PM Allison wrote:
I think you're thinking of the NEC V20/ uPD70108 and the V30/uPD70116 CPUs.
Plug-compatible with the 8088 and 8086, but with a couple of instructions
added to switch modes into 8080 emulation. Overall, emulation was pretty
good, but should have been Z80 instead of 8080 and there were a couple of
small bugs in the emulation that weren't fixed.
The V series were 1982 introduction. I was with NEC on the launch. By then
>
>Subject: Re: Legacy apps in Windows/OS X was Re: Old MS-DOS & Win
Software
From:
woodelf <bfranchuk at jetnet.ab.ca>
Date: Thu, 08 Dec 2005 19:30:35 -0700
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at
classiccmp.org>
What I do find odd that the 8086 came out first then a few years later
the 8088.
It still think the 8086/8086 could have had two instruction sets --
8080 emulation and
a better 16 bit design.
Not that I know of. I remember being able to get 8088s before the 86s
and that was back in 78 or early 79. Most vendors used the V20/V30, however, because they
were low-power CMOS.
They also implemented some of the 80186 entensions, like ENTER and LEAVE
and PUSHA/POPA and multi-bit immediate count shifts like SHR AX,5. If
you've got an old 8088/8086 box and need to run some code compiled to use
the 186/286 extensions, the V20/V30 is a very neat drop-in solution.
Not initially, The first generation of Vseries were NMOS. I have samples
of both.
The other differences were internal effective address calculation was handled
differntly from 8088 which shaved a few cycles of the execution. For the
same clock V series were between 5-10% faster. Also the V20/V30 had 8080
emulation.
Allison