RANA Systems Elite Controller, User Manual

Page: 311 / 328

ELITE SERIES USER MANUAL APPEN. A - DISK I/O
A total of 342 bytes are needed, shown by find-
ing the total number of bits (256 x 8 = 2048)
and dividing by the number of bits per byte
(2048 / 6 = 341.33). The transformation from the
six bit bytes to valid data bytes is also
performed by a one to one mapping, illustrated
in the figure below.
Again, the stream of data bytes written to the
diskette are a product of exciusive-ORs, similar
to the 5-plus-3 technique shown above.
Nybblized Data = Disk Byte
00 = 96 10 = B4 20 = D6 30 = ED
01 = 97 11 = B5 21 = D7 31 = EE
02 = 9A 12 = B6 22 = D9 32 = EF
03 = 9B 13 = B7 23 = DA 33 = F2
04 = 9D 14 = B9 24 = DE 34 = F3
05 = 9E 15 = BA 25 = DC 35 = F4
06 = 9F 16 = BB 26 = DD 36 = F5
07 = A6 17 = BC 27 = DE 37 = F6
08 = A7 18 = BD 28 = DF 38 = F7
09 = AB 19 = BE 29 = E5 39 = F9
0A = AC lA = BF 2A = E6 3A = FA
0B = AD lB = CD 2B = E7 3B = FB
0C = AE 1C = CD 2C = E9 3C = FC
0D = AF 1D = CE 2D = EA 3D = FD
0E = B2 lB = CF 2E = EB 3E = FE
0F = B3 1F = D3 2F = EC 3F = FF
* AA and D5 are reserved bytes.
F i g . A - 2 0 : 6 - p l u s - 2 C o n v e r s i o n T a b l e
P a g e A - 4 0