Apple Elite Series Computer Drive User Manual


 
ELITE SERIES USER MANUAL APPEN. A - DISK I/O
A total of 410 bytes is necessary to store the
original 256. This is calculated by finding the
total bits of data (256 x 8 = 2048) and dividing
by the number of bits per byte (2048 / 5 =
409.6) with two bits being unused. The data is
then transformed to valid “disk” bytes. This
involves simply looking at the following table.
Nybblized Data = Disk Byte
00 = AB 10 = DD
01 = AD 11 = DE
02 = AE 12 = DF
03 = AF 13 = EA
04 = B5 14 = EB
05 = B6 15 = ED
06 = B7 16 = EE
07 = BA 17 = EF
08 = BB 18 = F5
09 = BD 19 = F6
0A = BE lA = F7
0S = BF 1B = FA
0C = D6 1C = FB
0D = D7 1D = FD
0E = DA 1E = FE
0F = DB 1F = FF
* AA and D5 are reserved bytes
Fig. A-16: 5-plus-3 Conversion Table
Page A-35