% hexdump -C CS_update_20071221-1120_2_0_4.bci | head
00000000  43 53 20 55 70 64 61 74  65 20 32 31 2e 31 32 2e  |CS Update 21.12.|
00000010  32 30 30 37 0a 61 70 70  6c 69 63 61 74 69 6f 6e  |2007.application|
00000020  20 20 32 2e 30 2e 34 0a  6c 69 6e 75 78 20 6b 65  |  2.0.4.linux ke|
00000030  72 6e 65 6c 20 32 2e 36  2e 31 39 2e 32 0a 00 87  |rnel 2.6.19.2...|
00000040  08 a3 c3 99 34 47 9b 27  ca c8 82 e7 c7 cf b5 2d  |....4G.'.......-|
00000050  f2 9a 0b aa c9 1c 62 6b  0e 4e ac 03 33 3d a6 f6  |......bk.N..3=..|
00000060  d6 db 8f 1d 76 b7 3f 39  ce 06 09 84 fb 1e a5 e8  |....v.?9........|
00000070  5b 07 53 69 55 ff 9e 59  29 b1 da b9 51 70 b6 90  |[.SiU..Y)...Qp..|
00000080  a9 85 96 b2 ad 52 0f 64  5a 63 af 6c 95 bf f8 e2  |.....R.dZc.l....|
00000090  78 7e 91 44 0c 24 f1 2e  43 92 60 4d cc 56 13 5e  |x~.D.$..C.`M.V.^|
 

BCI file format
used by ECoS and CS60212 update data
Inventor: probably ESU.
 
// header of varying size
first comment line LF-char terminated telling type and date of update
second comment line LF-char terminated telling "application" followed by version ID in ASCII
third comment line LF-char terminated telling "linux kernel" and version ID (ASCII)
forth comment line LF-char terminated telling "hc12 1.6.23" (only ESU version since v1.1.2)
terminating zero byte (this zero byte indicates end of header)
 
// encrypted data
structure unknown