RE: 8088 and 610 saga continues...

From: Bill Degnan <*billdeg_at_degnanco.com*> Date: Fri, 28 Jan 2011 12:58:24 -0500 Message-ID: <5fd2faec$48bd9c6a$366307eb$@com> · billdeg_at_degnanco.com

> 
> > Now, let's apply this theory to our 8088 case... After careful
> > isolation, I was able to determine that memory is corrupted after
> > this call: 
> > 
> > 0040:0674                 call    far ptr 0F000h:0F003h
> > 
> > Which is, of course, a call to IPC. Until then, no 8088 code is
> > executed from memory locations 0xxx21h nor 0xxxA1h.
> 
> Okay, now we know the programm code that corrupt the data.
> 
> > But in the ROM code at 0F000h:0F003... yes, we have an instruction at
> > location 0FF021h, and guess what it is?
> > 
> > F000:F021                 in	al,21h
> > 
> > Now that's a coincidence - an instruction at location 21 which
> > accesses port 21!
> 

Is there a wedge that could be written/run before loading MS DOS to bypass 
this problem?

Bill

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