Category : System Diagnostics for your computer
Archive   : DMV.ZIP
Filename : DMV.DOC

************************************************************************
* *
* Announcing DMV ( Dynamic Memory Viewer ) *
* *
* A Debugging Tool for ASSEMBLER Programmer *
* *
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Version 1.01 ( Minor modification )

/A option is added to use the display as it is, i.e. without
re-initialization of display controller when DMV is activated.
PRT SC key problem is fixed. This key works as DMV screen print, only if
DMV is active.

Version 1.00 ( Initial release )

DMV is a special debugging tool for programmers, especially for ASSEMBLE,
that allows them to view contents of any memory address at any time
without halting PC execution.
DMV, once called, remains resident and occupies about 8k storage.
DMV traps keyboard interrupt ( INT 9 ) to check key for DMV, and traps
timer tick ( INT 1C ) to refresh the screen.
While refreshing the screen, DMV ignores NMI ( non-maskable interrupt )
which might occur if non-installed memory is to be displayed.

Activated by hitting Ctl-Alt-5(in cursor keys), DMV displays 256 bytes
of specified memory. The screen refresh cycle is under user control, from
1 to 255 timer tick periods ( about 55 ms / timer tick ) and is indicated
at upper right corner.

On the screen, there are 10 memory addresses assigned as function keys,
which can be used to load/store any memory address desired.

DMV contains an online help screen that describes how it is used.

DMV supports both black/white and color/graphic displays. If both are
installed, one can be used to view memory contents while the other is
used by any other program.

Because of the hardware limitation of color/graphic display, DMV on PC
disables video signal while refreshing the screen. This takes about 30ms
or PC/XT. If the screen is refreshed with every timer tick,a noticeable
flickering will occur with every refresh. It is thus recommended to use
increased refresh cycle time, or to use a mono display for DMV.