The address of the CCP/M data segment is returned in ES:BX by the S_SYSDAT call (9Ah). It is laid out as follows:
Offset Size Data Description ============================================================================ 00 DD sup_entry ; Entry to the CCP/M-86 Supervisor module 04 DD sup_init ; Supervisor cold start 08 DD rtm_entry ; Entry to the CCP/M-86 RTM module 0C DD rtm_init ; RTM cold start 10 DD mem_entry ; Entry to the CCP/M-86 MEM module 14 DD mem_init ; MEM cold start 18 DD cio_entry ; Entry to the CCP/M-86 CIO module 1C DD cio_init ; CIO cold start 20 DD bdos_entry ; Entry to the CCP/M-86 BDOS module 24 DD bdos_init ; BDOS cold start 28 DD xios_entry ; Far pointer to the XIOS main entry. 2C DD xios_init ; Far pointer to the XIOS cold boot routine. 30 DD reserved_entry ; Far pointer to an extra module (if present) 34 DD reserved_init ; that intercepts certain functions ; (network redirector?) If not present, ; segments are 0. 38 DD dispatcher ; Handles interrupt returns. Used by XIOS ; when it wants to do an IRET. 3C DD pdisp ; Handles far returns. Used by the XIOS ; when it wants to do a RETF. 40 DW ccpmseg ; CCP/M start segment 42 DW rspseg ; Segment of the highest Resident System ; Process loaded. The first 2 bytes of the ; indicated segment will be the segment of the ; previous RSP, or 0 at the end of the list. 44 DW endseg ; First paragraph beyond the area used by ; the OS. 46 DB modflags ; Bitmapped flags for which modules (as listed ; above) should have their initialisation ; function called. Bit 3 is tested for BDOS, ; bit 4 for CIO, bit 5 for the XIOS. 47 DB nvcns ; Number of virtual consoles. 48 DB nprinters ; Number of printers in the system. 49 DB nccb ; Number of character device control blocks. 4A DB n_flags ; Number of system flags. 4B DB sys_disk ; Default system disk (search path for ; command files). 4C DW mmp ; Maximum memory per process 4E DB 0 ; Reserved 4F DB dayfile ; If nonzero, system displays date and time ; when a CMD or RSP file is executed. 50 DB tempdisk ; Temporary file drive, 0=default or 1-16 51 DB ticks ; System clock ticks/second 52 DW lul ; Linked list of unused lock entries 54 DW ccb ; Address of the character device control ; block table 56 DW flags ; Address of the system flag table 58 DW mdul ; Linked list of unused memory descriptors 5A DW mfl ; Linked list of free memory blocks 5C DW pul ; Linked list of unused process descriptors 5E DW qul ; Linked list of unused queue descriptors 60 DW 0 ; Reserved 62 DW qmau ; Queue buffer memory allocation unit 66 DW 0 ; Reserved 68 DW rlr ; Linked list of processes that are ready to ; run. First entry is the running process. 6A DW dlr ; Linked list of processes that are ; waiting on system timers. 6C DW drl ; Linked list of processes that have just ; become ready to run. 6E DW plr ; Linked list of processes waiting on devices 70 DW 0 ; Reserved 72 DW thrdrt ; Linked list of all processes in the system 74 DW qlr ; Linked list of all system queues 76 DW mal ; Linked list of active memory allocation ; units 78 DW version ; Offset of version string (segment is CCPMSEG) 7A DW vernum ; Version number returned to function 0Ch 7C DW ccpmvernum ; Version number returned to function A3h 7E DW tod_day ; Days since 31-12-1977 80 DB tod_hr ; Time, hours (BCD) 81 DB tod_min ; Time, minutes (BCD) 82 DB tod_sec ; Time, seconds (BCD) 83 DB ncon_dev ; Number of consoles 84 DB nlst_dev ; Number of printers 85 DB ncio_dev ; Total number of character devices 86 DW lcb ; List Device control block table offset 88 DW open_file ; Bitmap of drives with open files on them 8A DB lock_max ; Maximum number of locked records per process 8B DB open_max ; Maximum number of open files per process 8C DW owner_8087 ; The process using the 8087. If 0, no ; process. If -1, no 8087. 8E DS 11h ; reserved 9F DB xpcns ; Number of physical consoles A0 DW off_8087 A2 DW seg_8087 ; Address of the 8087 interrupt vector A4 DW sys_87_of A6 DW sys_87_sg ; Address of the 8087 exception handlerJohn Elliott 16 July 2005
CP/M pages