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3. Depress system reset pushbuttons; the
system should stop at next ROS address 2BA. FLT
2 and block indicators should light (to check ROAR,
depress force indicator lever). Each subsequent
address will appear in the next ROS address field
and
represents the true next address.
4. Set rate switch to SINGLE CYCLE.
5. Single cycle through the microprogram and
assure that the proper conditions are set.
6. Single-step through the bump storage loop
and local storage loop.
7. Enter 243 in ROS address entry keys.
8. Set the stop on ROS address switch to ON.
9. Set rate switch to PROCESS.
10. Depress the system start pushbutton; this
will loop through all of the bump storage loop.
Current ROS will stop at 243.
Halt Loop: The following procedure can be used to
check the halt loop on QT200:
1.
Perform step (7) through (10) from previous
operation (microprogram reset).
2. Set the rate switch to SINGLE CYCLE and
continue single stepping through the microprogram
until current ROAR 150.
3. Set the rate switch to PROCESS. Depress
START.
Current
I
ROS Address
l
Condition
T
243
I
Set allow error and error
I
interrupt on
204
I
150
Halt loop
191
I
Halt loop
18C
I
Halt loop
208
1
Halt loop
4. Enter 208 in ROS address entry keys, set the
stop on ROS address switch to ON.
5. Depress the system reset pushbutton; CPU
will stop with current ROAR at 208.
6. Return the stop on ROS address switch to
normal; depress the system reset pushbutton.
When ROAR is at address 208, halt loop is op-
erating correctly. Set the rate switch to PROCESS
and depress the system start pushbutton; all four
clock indicators should come on.
Initial Program Load
To load a program, the channel number and the de-
sired device must be entered in the three load unit
switches.
Pressing the load pushbutton causes a system reset
and
initiates a read operation from the selected in-
put device.
158
(3/71)
Model SO FF.MM
The first 24 bytes read are placed in storage lo-
cations 0-23. The doubleword in location O is the
IPL PSW. The doubleword read in location 8 is the
channel command word (CCW). When chaining is
specified in this CCW, the operation proceeds with
the CCW at location 16 (CCW2).
After the input operation is performed, the 1/0
address is stored in bits 21-31 of the first word in
storage. Bits 16-20 are set to zero; bits 0-15 re-
main unchanged. The CPU proceeds under control
of the new PSW in location 0 and the load indicator
is turned off. Interruptions that become pending
during IPL are taken before instruction execution.
If the PSW in location O has bit 14 set to one, the
CPU is in the wait state after IPL.
If
the
1/0
opera-
tion and PSW loading are not completed satisfactorily,
the CPU idles and the load indicator remains on.
IPL Operation
IPL timing and clock controls are shown on Timing
Chart 202--Load Sequence, #T2021. Microprogram
logic flow is shown on Figure 174 in this manual.
The IPL load switch forces address 240 on QUlOO.
The error and H registers are cleared; MD is set to
3; S3 is set to 1; and the common ,reset routine is
initiated. At the completion of system reset, MD
=
3
and S3
=
1 branches the microprogram to QK800.
On
QK800: CCW2 is set up, the unit and channel
addresses are set in the L register, and zeros are
set in the R register for the command address. S3
is reset; S7 is set; and Start 1/0 is issued. The
program then loops on block 988 waiting for the chan-
nel response.
With the channel response, S3 is set on to break
out of the wait loop. Stats 0-3 are reset and a test
is made for condition code (CC)
=
o.
CC
=
1, 2. or 3
indicates that Start 1/0 is not accepted by the channel
and the microprogram will loop in block 98C.
CC
=
O indicates that Start 1/0 has been accepted and
begun by the channel. S7 is reset, Test 1/0 is
issued, and the wait loop is taken for channel re-
sponse. S3 is turned on with channel response and
a test is made for CC= 1 (channel end). The micro-
program loops on CC = 2 (channel busy) until CC = 1
is received. After channel end sets CC = 1, channel
status and unit status checks are made on logicQK801.
Channel status (40-47 of CSW) must be XXOOOOOO
or the program will loop on block 990. Unit status
(33-39 of CSW) must be OXXOlXOO or the program
will loop on block 919.
If
both status checks are
good, the PSW is loaded from location zero and pro-
gram execution is. started.
~
If
IPL hangs up with the CPU idle and the
load indicator on, the microprogram will most
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