Directory

The directory is a series of blocks which contain 8 file entries each (some may be unused). Each file entry contains a variety of information and uses 30 bytes:

Offset in directory entry
0	1~2	3~18	19~20	21	22	23~27	28~29
File Type	Main Link	Filename	Other Link	REL size	GEOS type	Date/Time stamp	Size

Let's take a look at each of these parts.

File type

This byte specifies the CBM file type in the lower 6 bits:

Value	Type
0	DEL
1	SEQ
2	PRG
3	USR
4	REL
5	CBM
6	DIR

Bit 6 is set to indicate the file is "locked" (read-only). Bit 7 is set to indicate the file has been properly closed. A standard CBM directory listing will show a * by the file-type if it is not properly closed; these are known a "splat" files.

Main Link

This points to the starting track and sector (first block) of the main file data. For GEOS VLIR files, it points to the VLIR table.

Filename

A filename may be up to 16 characters (bytes) long. Unused characters are filled with a "shifted space" = PETSCII code 160.

Other Link

This points to the starting track and sector of either a REL file's side-sector table, or to the only block of a GEOS "info sector".

REL Size

For RELative files, this byte indicates the record length (2 to 254 bytes). For GEOS files, it indicates the 'file structure': 0 is sequential and 1 is VLIR..

GEOS Type

This byte indicates the type of GEOS file:

Value	Type
0	Non-GEOS
1	BASIC program
2	Assembler file
3	Data file
4	System file
5	Desk Accessory
6	Application
7	Application data (user document)
8	Font file
9	Printer driver
10	Input driver
11	Disk driver
12	System boot file
13	Temporary file
14	Auto-execute file

GEOS Date & Time

These five bytes are used by GEOS as a last-modified date/time stamp:

Offsets 23~27 in directory entry
23	24	25	26	27
Year-1900	Month	Day	Hour	Minute

Notice the year is encoded as year - 1900. So byte 88 would appear for the year 1988 or byte 126 would appear for year 2026.

Size

This two-byte value (stored little-endian) indicates the size of all streams in blocks (multiples of 254 bytes rounded up). For example, if the file contained 1024 bytes, that would be 1024/254 = 4.0135... → 5 blocks.

For a standard PRG or SEQ file, use the number of blocks in the stream indicated by Main Link. For a GOES sequential-structure file, one would be added to account for the info block. For a REL file, you would add the number of blocks from Main Link to those from Other Link (other link typically has 1 to 6 blocks). For a GEOS VLIR file, one would need to add up each stream in the VLIR table, then add two: plus one for the VLIR table itself, and plus another one for the GEOS info block.