Let's me comment.
When Set Security Bit 1 is checked , Flash Magic sends
":020000030500F6"
But in Datasheet Table 12. ISP hex record formats
---------------------
03 Miscellaneous Write Functions
:nnxxxx03ffssddcc
Where:
nn = number of bytes in the record
xxxx = required field but value is a ‘don’t care’
ff = subfunction code
ss = selection code
dd = data (if needed)
cc = checksum
Subfunction code = 01 (Erase block 0)
ff = 01
Subfunction code = 05 (Program security bit, Double Clock)
ff = 05
ss = 01 program security bit
ss = 05 program double clock bit
Subfunction code = 08 (Erase sector, 128 B)
ff = 08
ss = high byte of sector address (A15:

dd = low byte of sector address (A7, A6:0 = 0)
Example:
:0300000308E000F2 (erase sector at E000H)
-------------------------------------
There are not ss = 00 imformation.
From my experiment,
ss = 00 causes Rectype 07's output's bit3 0 to 1 => flash Magic uses this command by mistake?.
ss = 01 causes Rectype 07's output's bit2 0 to 1 => mentioned by datasheet
ss = 02 causes Rectype 07's output's bit1 0 to 1
ss = 03,04 no change
ss = 04 causes Rectype 07's output's bit0 0 to 1 => mentioned by datasheet
Mucter,