IBM 4300 Manual page 55

Reset Function
In i t i al
Power-
Program Program Clear on
Area Affected Reset Reset Reset Reset
CPU
S S S S
Channels R R
R
R
PSW U C C C
CPU timer U C C C
Clock comparator U C C C
Time-of-day clock
U 1 Ul Ul
T
Control registers U I I I
General registers U U C C
Floating-point registers U U C C
Capacity counts U U I
I
Page descriptions U U
C
C
Storage
U
U P P
Machine-save information
U2 U2
Y Y
Explanation:
C The condition or contents are cleared. If the area affected
is a field, the contents are cleared to zero with valid
checking-block code.
I The state or contents are initialized. If the area affected
is a field, the contents are set to their initial values
with valid checking-block code.
P The first n storage pages are cleared and made address-
able, where n is the lesser of the available-frame-
capacity and page-capacity counts. Any remaining pages are
left disconnected.
R I/O-system reset is performed in the channels, and pending
I/O-interruption conditions are cleared. As part of this
reset, system reset is signaled to the I/O control units
and devices configured to the channels.
S The CPU is reset; current operations, if any, are termina-
ted; interruption conditions in the CPU are cleared; and the
CPU is placed in the stopped state.
T The time-of-day clock is initialized to zero and validated,
and it enters the not-set state.
U The contents remain unchanged. However, the resulting
value is unpredictable if an operation is in progress that
changes the contents of the field at the time of reset.
Y The machine-save information is made invalid.
1 Access to the time-of-day clock by means of STORE CLOCK at
the time a reset function is performed does not affect the
value of the time-of-day clock.
2 If a machine-save function is in progress at the time of
the reset, the machine-save function is halted, and any
partially altered machine-save information is made invalid.
Summary of Reset Actions
4-22 IBM 4300 Processors Principles of Operation