! 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
44 bytes key -track 0 cylinder 0 96 bytes data area
Format 5 DSCB type label used to be compatible with other systeas. 05 05 05 05 00 FORMAT 5 LABEL L 44 Byte Key 96 Byte Data Area
Figure 3-9. Record 6 For.at 4096 bytes -1 page, track 0 or track 1 (2314/2319 devices only).
F3 Record is reserved for IBM use, and is referred to as a
filler record.
Figure 3-10. Record F3
1624 bytes track 1 (2314/2319 devices only) Record F4 is used only on 2314 and 2319 to align Record 4 on the
track.
Figure 3-11. Record F4 824 bytes -cylinder 0, track 1 (2314/2319 devices only).
The first segment of Record 4 is used for paging.
Figure 3-12. Record 4 74 IBM VMj370 Service Routines Program Logic
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