Image Map Image Map
Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Info on NEC V 20

  1. #1
    Join Date
    Nov 2009
    Location
    Dublin, Ireland
    Posts
    1,149

    Default Info on NEC V 20

    Is it worth replacing the 8088 in a 5150 with a NEC V 20? What speed benefit will I get?

  2. #2

    Default

    about 10% in synthetic benchmarks, but the main benefit is support for the 286 instruction set

  3. #3
    Join Date
    Nov 2009
    Location
    Dublin, Ireland
    Posts
    1,149

    Default

    Quote Originally Posted by maxtherabbit View Post
    about 10% in synthetic benchmarks, but the main benefit is support for the 286 instruction set
    What speed chip can I use?

  4. #4

    Default

    I believe the V20 supports the 80186 instruction set, not the 286.

  5. #5

    Default

    Quote Originally Posted by fjk61011 View Post
    What speed chip can I use?
    anything rated for 5MHz or higher

  6. #6

    Default

    Quote Originally Posted by BillGee View Post
    I believe the V20 supports the 80186 instruction set, not the 286.
    You're right. I said "286" out of convenience since most of the software that purports to "require 286" actually requires 186

  7. #7
    Join Date
    Nov 2009
    Location
    Dublin, Ireland
    Posts
    1,149

    Default

    Quote Originally Posted by maxtherabbit View Post
    anything rated for 5MHz or higher
    Would a 16 MHz work in the 5150?

  8. #8

    Default

    Quote Originally Posted by fjk61011 View Post
    Would a 16 MHz work in the 5150?
    Yes. There are no internal multipliers or any such silliness, the CPU just runs at whatever clock it's being fed.

  9. #9
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    2,393

    Default

    Quote Originally Posted by fjk61011 View Post
    Would a 16 MHz work in the 5150?
    I'm guessing you're looking at that perpetual eBay listing for 16mhz V20s; I bought two from it and they both worked fine in Tandy 1000 EX/HXes. (switchable 4.77/7.16mhz machines.)
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  10. #10

    Default

    Quote Originally Posted by BillGee View Post
    I believe the V20 supports the 80186 instruction set, not the 286.
    Which is equivalent to the 286's real-mode instruction set. Of course it doesn't support protected mode, but any programs designed for a 286 in real mode will run on an 80186/80188 or NEC V-series CPU.

    The NEC V-series chips also have an 8080 emulation mode, allowing 8-bit CP/M code to be run.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •