Hexadecimal
Displacement
------------ 0 0 8 10 10 18 1C 20 24
28 30 38 40 48 50 57
58
5C 60 61
62 7C 80 88
Field
Name DIOSECT DSECT IOOLD DC DIOCSi DC gbIsT IQ DS PiAIT DC 1D'0' 1D'0' DMSIOW OP--- CL8'WAIT' Field Description, Contents, Meaning I/O cld PSW (from interrupt routine) CSW (from interrupt routine) DIOSECT DC C'DSK-' Filled in to correct symbolic disk number DC DC QQDSK1 DC QQDSK2 EQO cell Chain CCii----- CCii CCi1A CCW CCW2 CCW CCli3 CCW RiCCW CCli F'O' F'O' F'O' First two bytes are always 0 QQDSK1+2 Halfword X!07!,SEEKADR,X'40',6 X'03',O,X'40',1 X'31',SEEKADR+2,X'40',5 X'08',*-8,0,1 X'00',*-*,X'20',*-* copy of 16th track disk Seek Seek or set sectcr Search TIC back to search
Read or write data
address SEEKADR DC XL7'00' Seek/search information (first 3 bytes are 0) SECTNOM DC X'OO' ILQ LASTCYL DC F'O' LASTHED DC F'O' DEVTYP DC X'OO' DIOFLAG DC X'OO' in DIOFLAG TOO BIG EQO --X'04'--- liRTKF EQU X'02' QQTRK EQO X'01' DIAGNUM EQU SENSB 24 XL24'00' OF Sector number Becomes last cylinder number used
Becomes last head number used
A*1 01=2311, 08=2314, 09=3330 A*2 RDTK/WRTK flag:
Byte count is greater than 800 Writing first chain link
Handling first chain link Number assigned by CP for tIAGNOSE I/O Sense information SENCCli DC DS CCli X'04',SENSB,X'20',24 REAt 24 BYTES SILl (Scratch area, for CVD use, etc.) !1! Order 90 XRSAVE DS 15F --Registers 0-14 saved here for RDTK/WRTK CC DC AL3(0) First 3 bytes of R15 error code CF ERRCODE DC AL1(*-*) Error code (in R15 at exit) !QllQ!!1!9 I!Q in Order DO FREERO DC F'O' ----wo. cf doublewords of free storage (if any)
D4 DIOFREE DC F'O' Address of free storage for buffer or CCis D8 EO E8 E9 EA SAVEADT DC CCliX CCW DIAGRET DC IOCOMM DC LASTREC DC F'O' Handy place for an ADT address X'23',SECTNUM,X'40',1 Set sector X'OO' A*3 CP's tIAGNOSE return code if nonzero X' 00' A*4 Set to read (06) or write (05) X'OO' A*5 Number (1-14) of the last reccrd processed Section 2. CMS tata Areas and Contrel Blocks 161
DMSCCB DMSCCE describes all fields of a DOS Co.mand Control Block (CCB). This DSECT is used by DMSXCP to map the CCB specified by a user for an SVC 0 (EXCP) and passes the address of CCB to DMSXCP. I o I A*1 1*2 A*3 1*4 I A*5 A*6 1---------------------------------------------------------
8 I 1*7 CCBCCW A*8 CCECSW 10 I CCBLDITB CCBLCCWE 1--------------------------------------------------------
18 1///////////////////////////1 A*9 CCEFSCCW 1----------------------------------------------------- 20 I CCBRDCCW CCBWTCCi 1------------------------------------------------- 28 I CCBLWCCW 1///////////////////////////
1------,--------------------------------------------------- 30 1///////////////////////////1/////////////////////////// 1--------------------------------- 38 I CCBNCCB 1///////////////////////////
Hexadecimal Field
Displacement Name Field Description, Contents, Meaning o
o
2
2
3 CCBST CCBD CCBL-Elf CCBCNT EQU EQU DS DS CCBERMIP DS CCBCOM1 DS
Bits defined CCBWAIT--EQU CCBEOF EQU CCBIOERR EQU CCBERROK EQU CCBRDC EQU CCBPDE EQU CCBDCV EQU CCBUERR EQU CCBCOM2 DS !!i!§ CCBDCCNT EQU CCBTRKOV EQU CCBEOC EQU CCBDC EQU CCBNOREC EQU CCBRETRY EQU CCBVER EQU CCBCC EQU *
* OCL16 XL2 OXL4 XL1 in CCBCOM1 --X'80'-- X'40' X'20' X'10' X'08' X'04' X'02' X' 01' XL1 in CCBCOM2 -X'80'-- X'40' X'20' X'10' X'08' X'04' X'02' X' 0 l' Start CCB Command control block lIapcftherOS CCB Residual count
Four bytes used to check errors 1*1 Communications byte 1 1*2 Traffic bit (set at CE) End cf file Unrecoverable I/O error AcceIt unrecoverable error
Return data checks Post at device end
Return data check RD/CHK User error routine Communications byte 2
Data check in count area
Track overrun
End cf cylinder
Data check
No record found
Retry no record found Verify error Command chain (retry)
162 IBM VM/370 Data Areas and Control Block Logic
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