The two main BS2000 access methods are PPAM (Privileged Primary Access Method) and PTAM (Privileged Tape Access Method). PPAM and PTAM are used by DMS to handle file access. All file access requests are passed on to PPAM/PTAM by DMS.
PPAM handles all disk file access requests. PPAM uses standard blocks, known as PAM pages (also called PAM blocks or half-pages (HPs)). It supports the access methods ISAM, SAM, UPAM, FASTPAM, DIV and EAM for disk files.
PTAM handles all tape file access requests. PTAM supports not only the tape access method BTAM but also the access methods SAM and UPAM if these methods are used for processing tape files. PTAM functions independently of PPAM. From the viewpoint of PTAM, the content of a tape consists of a sequence of data blocks and tape marks.
