Epson PX-8 Technical Manual page 148

REV.-A
Data field
FF .. - - _. _ A series of Block data'-
'--_-,. _ _ _ .... 80-bit zeros
--.l-...J..-H...J...-I.......J...+¥ .................................................... ~ .......................
-+-+--'--"'--'---"T"""---'
IBG
'--'I---Block identification number
1
1 -f"W-
Header block
'----Block :dentlfler "0"- Data block
I
"E": EOF block
1
character value by
Cyclic Redundancy
Check (CRC)
... 1 . .
_ - - - - - + - - -
Processed by CRC feature - - - - I - __
-"I
I I I
1
1 i , .. ..
- - - - B l o c k length - - - -........
...,1
1
Fig. 3-2 Microcassette Tape Data Format
One tape reel (or one tape volume) consists of a directory and one or more files. The directory
consists of three blocks; the first block contains identification data for the tape and directory and
the second and third blocks contain control data for the files.
One file consists of a header block, one or more data blocks, and an end-of-file (EOF) block. Fig.
3-3 illustrates the general data structure of one reel.
File n
~t----------------Tape
reel (volume)
---------~----.-.j
Directory
I
File 0
I
File 1
I ))
I
File N
~
' - i
' - - - - - - - - ,
First block
Second block Third bloCk - -
Tape and directory identification data 'File control data (for up to 8 fileS)' File control data (for up to 4 fileS)1
Header block
Data block 1
File structure data' File data ,
v
These data are read
into memory by MOUNT.
Data block 2
Data block n
File data' ))
I
File data File data
Fig. 3-3 Cassette Tape Reel Structure
3-2
EOF block
End of file