VFP Display Aliasing
Because of the way Win95 switches tasks, when the Run box
is checked and the Execute menu's Chunky option is checked,
some register displays may not behave as expected. What is
happening is that the emulator is running many instructions
before the system can update the display, and the register(s)
can appear to be static, unchanging. They're changing and
being updated, it's just that they're back to the same state
that they were when they were last refreshed on the display.
Remember that the emulator is going much faster than the
display can follow. Unlike an analog display system,
which can follow such changes (and shows them as a blur,
usually), the VFP regularly "samples" the registers and
so displays a clear, if non-intuitive, value. Also, the
updates always occur at integer multiples of instruction
executions; that has the effect of making the displays
"alias" against the operating rate of various instruction
The faster your computer and its associated display
hardware is, the more useful the VFP is during RUN.
You can de-select the Chunky option and the emulator
will run one instruction at a time, instead of the
large batches it normally does. This has two effects;
one, it provides more of a timing window for the display
to update, and two, it slows down the emulator to a very
noticeable degree. Sometimes you'll want to do this,
especially when involved in software development.
You can also single step the emulator, which
will result in the expected correct register displays.