FLEX is the name of the Operating System for the Motorola 6800 and 6809. IDA can disassemble OS9 object and FLEX STX files
Assembler code\
TEXT:102F bcs loc_1065
TEXT:1031 leax ,u
TEXT:1033
TEXT:1033 loc_1033 * CODE XREF: start+25↓j
TEXT:1033 clr ,x+
TEXT:1035 subd #1
TEXT:1038 bhi loc_1033
TEXT:103A stu $80
TEXT:103C ldd ,s++
TEXT:103E std $B0
TEXT:1040 ldd ,s++
TEXT:1042 leax d,u
TEXT:1044 stx $82
TEXT:1046 ldd $B0
TEXT:1048 leax d,x
TEXT:104A stx $B0
TEXT:104C ldx $88
TEXT:104E OS9 F$All64 * '0' * Allocate Process/Path Descriptor
TEXT:1051 bcs loc_1065
TEXT:1053 stx $88
TEXT:1055 OS9 F$Ret64 * '1' * Return Process/Path Descriptor
TEXT:1058 leax word_16A2,pc
TEXT:105C stx $26
TEXT:105E leay word_1067,pc
TEXT:1061 OS9 F$SSvc * '2' * Service Request Table Initialization
TEXT:1064 rts
TEXT:1065 * ---------------------------------------------------------------------------
TEXT:1065
TEXT:1065 loc_1065 * CODE XREF: start+1C↑j
TEXT:1065 * start+3E↑j
TEXT:1065 jmp $6B
TEXT:1065 * End of function start
TEXT:1065
TEXT:1065 * ---------------------------------------------------------------------------
TEXT:1067 word_1067 fdb $7F00 * DATA XREF: start+4B↑r