A Code Segment Descriptor is used to reference the Code in a CodeFile.
It is created as an entry in the Segment Dictionary by the compiler with a Tag 3 and it contains the Segment Address and the Size in Words of the Code Segment.
Tag 3 - SegDesc | ||
---|---|---|
Field | Name | Description |
[39:20] | SizeF | Size of the Code Segment in Words |
[19:20] | AddressF | The Sector Address in the Codefile of the start of the Code Segment. |
A PCW contains a Segment Dictionary Index (SDI) of a Segment Descriptor which describes a Code Segment.
The PCW contains a Word Index (PIR) of 13 bits and a Syllable Index (PSR) of 3 bits and they reference a Code Syllable in the Code Segment.
Since the PIR field is 13 Bits, a Code Segment is limited to 8191 Words (273 Sectors).
The BRxx Branch Operators also contain a PIR of 13 bits.