24 bytes track 0 cylinder 0 1PL record -puts system into wait state if storage device is loaded (via IPt function).
f 1 100 02 00 00 00 00 00 00 03 00 00 00 20 00 00 CO 00 00 00 00 00 00 00 001 '--- J
Figure 3-4. Record 1 For.at l 4096 bytes - track 0 cylinder 0 Checkpoint record -this is the Checkpoint prograa load at V8/370 1Pt ti.e to retrieve and save control inforaation for a war. start.
Figure 3-5. Record 2 Format 1 consists of a 4-byte key and an aO-byte record.
Key Data
, I I Pointer key I Key I Label FO to VTOC 00 40 00 CP370 40 pointer
to user I I I I Directory I .J 0 3 0 4 10 11 16 21 41 46 51 52
Figure 3-6. Record 3 Format
72 IBM VM/370 Service Routines Program Logic
i I 401 I I 56 79
! 1024 bytes -track 0 cylinder 0 i I Record 4 is an allocation byte map used to identify cylinder usage. I Each byte ccrresponds to one cylinder; the value of the byte indicates
the type cf usage for the cylinder. Value 00-- 01 02 04 tem{:orary per.anent
T-disk 00 00 01 00 04 02 00 FF 0 O. 00 ... I Cylinder beyond the last cylinder
that can be allocated. This point varies
depending on the Figure 3-7. Record 4 Format 2 44 bytes key - track 0 cylinder 0 96 bytes data area
Format 4 DSCB type label -used to be compatible with other systems. I , r I 04-)04 I I FORKAT 4 LABEL L-- ____ .J 44-tyte Key 96-byte Data Area
igure 3-8. Record 5 Format Chapter 3. The Format Service Program 73
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