May 2014
Intermediate to advanced
320 pages
13h 41m
English
Content preview from Servicing Personal Computers, 3rd Edition
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266 Servicing Personal Computers
User and supervisor modes
In the design of the 68000, Motorola attempted to address a number of problems which had
previously beset
8-bit
microprocessors. In particular, it was felt that there could be significant
advantages in separating the operating system from an application program running under it.
The separation of the operating system and any applications program which would run
under it, is provided by allowing for two basic modes of operation; 'user mode' and
'supervisor mode'.
User mode refers to CPU operations which relate to the applications program whilst
supervisor mode is reserved for sole us ...