Perverted DOS idea

From: Roger Ivie <rivie_at_teraglobal.com>
Date: Thu Jun 8 10:15:30 2000

>How little memory could you run something like, say, DOS 3.3 in? All I
>would be supporting is a basic command set like COMMAND.COM, EDLIN, DEBUG,
>maybe XCOPY, etc. And are the INTs documented anywhere?

You could execute from disk, requiring just enough memory to hold a
disk sector. I.e., instead of reading memory by indexing into an
array like:

    Instruction = Memory[ IP ];

do something like:

     Block = IP >> 7; /* 128-byte sector, anyone? */
     Offset = IP & 0x7f;

     read( File, Block );
     Instruction = Memory[ Offset ];

-- 
Roger Ivie
TeraGlobal Communications Corporation
1750 North Research Park Way
North Logan, UT 84341
Phone: (435)787-0555
Fax: (435)787-0516

Received on Thu Jun 08 2000 - 10:15:30 BST