How compatible were "MS-DOS Compatible" machines? - test-drb@ccmp.vtda.org

30 Jan 2008

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  Date: Wed, 30 Jan 2008 11:07:38 -0600
 From: Jim Leonard 
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   In the early
days, it was possible to call BASIC subroutines.  But, I
 don't think that they kept the same addresses for long.  
 Wow -- while that's cool, what was a useful application for that? 
 Borrowing the use of the floating-point routines, perhaps?  ROM has a
 faster access time than RAM, but would it have been all that much faster
 than doing it yourself, or would it have just been merely convenient? 
Any IBM system with BASIC-in-ROM kept the same addresses for 
subroutines throughout the life of that feature.  That's why you can 
run PC-DOS BASICA only on those machines having the ROM BASIC.  For 
generic MS-DOS, MS supplied GWBASIC as an option (which I still use 
on my XP-equipped machine when I need to do some quick figuring).

Several very early games required BASIC-in-ROM--the basic 5150 
shipped with 48K of DRAM, so memory was at a premium.  I don't think 
any productivity tools made use of the ROM BASIC, however.  Do any of 
the IBM diagnostics use it?

Cheers,
Chuck