Legacy apps in Windows/OS X was Re: Old MS-DOS & Win Software

[Allison]

>
>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:
>
>>>
>>>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.
>
>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

>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