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Z Drivers (18 bits, Z, N)
The Z drivers 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 input/ output channel.
Arithmetic Unit (18 bits, no abb., N)
The arithmetic unit performs the following functions on the contents of Y and/ or M and puts the
result in the Z drivers.
Binary Addi ti on
Logical "AND"
Logical "OR"
Logical "EXCLUSIVE OR"
Shift left, right, circulate, etc.
Bit change
Scan
Other misc. operations as required, i.e., address modification
Branch Flip-Flops (3FF, BFF's, A)
The plus, zero and even flip-flops are connected to the Z drivers. These three flip-flops are set
at the completion of every non-branch instruction and will reflect the branch conditions of any
data passing through the Z drivers. The Plus Flip-Flop (PFF) stores the status of the high order
bit of the result.
The Zero Flip-Flop (ZFF) stores the status of the entire result. The Even
Flip-Flop (EFF) stores the status of the low order bit of the result. The result of an operation
is available for test on the next instruction.
Plus Flip-Flop (1 bit, PFF, A)
The PFF records (for testing) the condition of Z(18) at the end of an instruction.
If
Z(18)
was zero, the PFF would be plus; but if Z(18) was one, the PFF would be minus. The
notation Z(l8) refers to bit position 18 of Z, i.e., the high order position of Z.
Zero Flip-Flop (1 bit, ZFF, A)
The ZFF records (for testing) the condition of Z at the end of an instruction.
If
all of the Z
drivers were zero, the ZFF would be zero; but if any of the Z drivers were non-zero, the
ZFF would be non-zero.
Even Flip-Flop (1 bit, EFF, A)
The EFF records (for testing) the condition of Z(l) at the end of an instruction. If Z(l) was
zero, the EFF would be even; but if Z(l) was one, the EFF would be odd.
Insert Switches (18 switches, S, A)
The switches are located on the control console and are described in the discussion of the control
console. They can be gated in under program control.
_Internal Function Drivers (10 drivers, IFD, A)
These drivers can activate special control functions.
[ID/A\11/A\~~tr
c::l
~@------------
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