IBM 5110 User Manual page 120

Note:
Assuming 010 is 0, the APL internal representation of a
character is equivalent to the hexadecimal value of that character's
index in the atomic vector. For example, the APL internal
representation of the character A (OA V [86]) is hex 56 (the bit value is
01010110). You can determine the bit value of the atomic vector index
using the encode (T) function. For example:
2 2 2 2 2 2 2 2
T
86
e
1. 0
:1' 1
P
:l 1 0
1
~HexadeCimal
56
The EBCDIC character A has a hexadecimal value of C1 or a decimal
value of 193. In non-translate mode (and 010+1), when the EBCDIC
character A is read from a diskette, the character is stored internally
and displayed as a lowercase h (OAV [193]).
The nontranslate format allows only character vectors to be written to
the file. Also, each sector on the diskette is considered one record.
Therefore, if you specify,that three records should be read or written,
you will read or write three sectors on the file.
Sector Boundaries
When nontranslate format is used,
three records are equal to three sectors.
Input/Output Control 115