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Re: [midatlanticretro] Force-feeding an 8087 to a PC

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  • Brian Heise
    The PCID cartridge does one thing, it changes the Identification byte that tells the software, what kind of computer it is dealing with. Nothing more. With
    Message 1 of 8 , Mar 2, 2006
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      The PCID cartridge does one thing, it changes the Identification byte that tells the software, what kind of computer it is dealing with.  Nothing more.  With this being the case, a program might have instructions for a 5150 running an 8087 on it, but would bypass those instructions if it knew a jr was running the software in order to alleviate issues with the running of the program.
       
      There were 3rd party as well as IBM original adapters to run monitors other than the 4863.  If I remember correctly, the 4863 came out right before the 4860 was released.  Very few pre-dating release pictures of the jr have the 4863 monitor in them.  I could be rememebring wrong of course.
       
      Brian

      Chris M <chrism3667@...> wrote:
      please to make your acquaintance Brian.
      What is the PCID cart anyway? Not familiar with that
      one. Jim Scheef who's on this list is a fan of the jr
      also.
      While on the topic, I remember seeing an add with an
      IBM 5151 mono monitor sitting atop the jr. Was there
      an actual 3rd party add that made this possible?

      --- Brian Heise <nampcjr@...> wrote:

      > I was speaking with one of the members of micro-zone
      > (Thats my site BTW) about doing this addition.  The
      > programming is not going to be found in any jr
      > specific programs, but is found in some general PC
      > programs.  I wish to make a decent daughtercard with
      > soldered-on solckets etc....Im not slinging the iron
      > around TOO much ;)....As was told to me, the Racore
      > PCID cartridge "should" be able to help the jr look
      > for those calls to the 87. And my jr is pretty much
      > maxed out...booting HDD, 1.4mb floppy, 5.25
      > (standard), blah blah blah...all the good stuff...
      >   
      >   Brian
      >   
      >  
      >
      > Chris M <chrism3667@...> wrote:
      >   Brian, why in heaven's name are you soldering
      > anything! If it's as easy as "wiring it up" to a
      > Peanut in a similar fashion as you see in the PC's
      > schematic, then yes you do need a daughtercard, but
      > it's going to plug into the the 8088's space (which
      > granted will require some desoldering), and the 8087
      > will plug into a socket (the 8088 too). Perhaps some
      > jumpers possibly. Don't know if support is required
      > in
      > the BIOS. The 8087 works by having the 8088 offload
      > certain instructions to it, but this requires
      > special
      > programming...it's not automatic. People used to
      > think
      > that having a math coprocessor automatically speeds
      > up
      > their computer. Not so. The software has to take
      > advantage of the chip (it has it's own instruction
      > set), stuph like Autocad and the like.
      > My guess is this is a more complicated project then
      > it at first seems. Proceed slowly. And for Pete's
      > sake, put down that steaming soldering iron! LOL LOL
      > And is the Peanut a minimum or maximum mode design?
      > Try the question on classiccmp.org. Interesting, but
      > proceed cautiously.
      > There's also www.micro-zone.com for Peanut
      > afficianados.
      >
      > --- Brian Heise <nampcjr@...> wrote:
      >
      > > I've been doing some reading of the Sams
      > > Computerfacts schematics for the IBM 5150 and the
      > > PCjr in order to see how to build a daughtercard
      > for
      > > the jr to add a 8087 math coprocessor.
      > Now...beofre
      > > shooting at me...there was one made back in the
      > day
      > > for just this purpose.  Because it was nearly $200
      > > or so, it didnt sell well.  anyone else out here
      > > have experience with this modification?  Seems
      > like
      > > a pretty easy solder job on a blank breadboard,
      > but
      > > my reading of schematics can be juvenile at
      > times...
      > >   
      > >   Brian
      > >
      > >            
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    • Chris M
      dude, what s a 4863? Is the 4860 the standard color unit for the jr? __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo!
      Message 2 of 8 , Mar 2, 2006
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        dude, what's a 4863? Is the 4860 the standard color
        unit for the jr?

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      • Brian Heise
        The 4863 is the IBM PCjr Color Display Chris M wrote: dude, what s a 4863? Is the 4860 the standard color unit for the jr?
        Message 3 of 8 , Mar 2, 2006
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          The 4863 is the IBM PCjr Color Display

          Chris M <chrism3667@...> wrote:
          dude, what's a 4863? Is the 4860 the standard color
          unit for the jr?

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