A Brief History of the Pick Environment in Australia - History of Computing: Learning from the Past - page 148

2.1 The Data Model

The actual database was modeled as a “Hashed Indexed Sequential Access Method”
(HSAM) mechanism. Each data record was indexed by a unique primary key that is
used to calculate which frame (or bucket) is its home location inside a given fixed-
size file. So for a given file and frame the read and write commands “compiled”
directly to an absolute disk, head and sector address.
Unlike other data models Pick's record structure is not predetermined by a Data
Definition Language. Traditionally a database is created with the required number of
tables, each table having its own peculiar structure. In Pick, one created files as

Table 1. Student Record Layout in Pick

Attribute # Data

0..11 Traditional fields student ID, names, addresses, sex, phone numbers, DOB

12 Subject code (text)(MV Controlling)(Associated to file Subjects)

13 Semester code enrolled (text)(MV Dependent #12)

14 Result (number)(MV Dependent #12)

15 Assignment result(s)(MV Dependent #12)(Multi-sub-valued- multiple assignment

results allowed)

16… More attributes

When we look at an actual record, it might be represented like this …

Fig. 1. Representation of a Student Record