HP 61010A Owner's Manual page 27

determined by the settings of the base, complement,
length, start, threshold, and logic sense fields. If you
change any of these settings (except base), the display area
on your screen becomes blank. This indicates that the way
the present input data is displayed is invalid. The display
area remains blank until the next time input data is read
by the Digital Input.
BASE • contains four choices (one is hidden), that allow
you to represent input data on the display area of the
Interactive Instrument Window in decimal, binary, octal,
or hexadecimal format. The current selection is always
bright. If the desired base is not bright, use the arrows at
the bottom of the field to move the desired base to the
center location. When the desired base appears in the
center location, point to and select it to activate the base.
The newly selected base will now be bright to indicate that
it is the current selection.
SET COM PL - when the decimal base is pointed to and
selected, the set compl field appears on your screen as
shown in Figure 3-1. When you point to and select this
field, it toggles between 2's arid UNSIGN. The field
always indicates the complement that is currently active.
Selecting this field will activate the hidden choice. When
2's-com.plement is active, your input data is displayed as
positive and negative decimal values on the display area of
the screen. The left-most bit of any specified data field
automatically becomes the sign bit. Unsigned format
displays your input data as positive decimal values only. If
a base other than decimal is selected, the set compl field
does not appear on the screen.
To help you understand how the base selection affects the
way input data is displayed, lets assume that input bits 0
through 12 are set low, and bits 13 through 15 are set
high. Depending on the base, the input data is displayed
as follows:
Decimal (2's compl) - -8192
Decimal (unsigned) = 57344
Manual Instrument Control 3-3