Disk Cartridge For The Console File - IBM System/370 145 Manual

the process position, and the CPU must be in process mode.. When the
system is in this status, an initial microprogram load
(I~PL)
is
initiated automatically when system power is turned on.
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Casing - 8 inches square
Recording disk
Sector pulse hole
Figure 10.15.2. Disk cartridge for the console file. Shaded areas
represent recording disk showing through cutout areas
in casing. Dotted lines show recording disk inside
the casing. Eight holes in the periphery of the disk
generate, via photoelectric sensing, sector pulses to
indicate beginning of sector.
When power is already on, IMPL is initiated via the start console
file key. Pressing this key causes power to be turned on in the file
(it is normally off), and as soon as the disk is up to speed--about five
seconds--reading from the console file begins. The key remains red from
the time i t is pressed until reading begins and then turns white to
indicate that loading has begun successfully. The key remains red if
the disk does not turn, a disk is not mounted, etc.
Approximately 45 seconds are required for the loading of 32K of
control storage (includes maximum arm positioning time). During
loading, considerable error checking occurs to ensure that the microcode
is read and loa~ed into control storage correctly. If an error is
detected, the console file key turns red to inform the operator. The
white indication and file power are turned off at the successful
completion of control storage loading. The system reset microcode (just
loaded) is executed, and the CPU is placed in the stopped state, ready
for an IPL of the operating system.
The basic system microcode control storage space requirement includes
room for a patch area, into which the user or the customer engineer can
load temporary patch engineering changes (EC's) from an I/O device at
the completion of IMPL. When temporary patches are received, the
customer engineer plugs a jumper card into the system to cause a request
for patch loading to be typed on the console at the completion of each
IMPL procedure. Checking is performed to ensure that EC's are correctly
loaded. Once microprogram patches have been made, no additional changes
28 A Guide to the IBM System/310 Model 145