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A novel and extremely effective feature are the Branch Flip-Flops (BFF). After the data has
been processed by the arithmetic unit, it is sent to the Z drivers which are a common data
distribution center for all data coming from the arithmetic unit and going to a working register,
memory, control unit, or an output channel.
Since the results of instructions go through the Z
drivers on the way to their destinations, this is a point which is common to the result of every
instruction.
The branch flip-flops record whether the result was zero or non-zero, even or odd,
plus or minus.
This provides simple tests for equality, or for the end of a loop process. The
branch flip-flops are not limited to these uses, and can be used with powerful effect.
REPRESENTATION OF INFORMATION IN MEMORY
Alphanumeric Data Words
Each DATANET-30 word can contain three six-bit alphanumeric characters. The 64 possible bit
combinations can be assigned to 64 symbols in any manner desired, because the DATANET-30
does not use alphanumeric data as such. Therefore, other system conditions (e.g., the character
set of the computer,
if
there is one in the system) will determine the actual bit pattern-to-symbol
assignment. An alphanumeric data word is formulated like this in memory:
WORD IN
MEMORY
Numeric Data Words
an alphanumeric character
an alphanumeric character
an alphanumeric character
r ..
BIT POSITION
Numbers are represented by integers in the DATANET-30. Negative numbers are represented
in the two's complement form. The DATANET-30 utilizes two's complement arithmetic. There-
fore, the high-order bit is properly thought of as the sign bit, when it is understood that the sign
is a two's complement sign, not an algebraic sign. A few examples are given below to show how
various numbers are represented in the DATANET-30. The bits are shown in groups merely to
simplify the presentation.
[ID£1J£~[filc:J ~@------------
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