# 6809 OS9 Flex Disassembler FLEX is the name of the Operating System for the Motorola 6800 and 6809. IDA can disassemble OS9 object and FLEX STX files and is probably the most powerful disassembler for that platform. Assembler code ```armasm TEXT:54A5 TEXT:54A5 * =============== S U B R O U T I N E ======================================= TEXT:54A5 TEXT:54A5 TEXT:54A5 sub_54A5 * CODE XREF: sub_4F06+78↑P TEXT:54A5 * sub_5048+1CB↑P ... TEXT:54A5 pshs dpr,y,u TEXT:54A7 ldy 7,s TEXT:54AA ldx ,y TEXT:54AC ldd 9,s TEXT:54AE aslb TEXT:54AF leay b,y TEXT:54B1 ldd $B,s TEXT:54B3 pshs a,b,x TEXT:54B5 tfr b,a TEXT:54B7 ldu ,y TEXT:54B9 beq loc_54BD TEXT:54BB jsr ,u TEXT:54BD TEXT:54BD loc_54BD * CODE XREF: sub_54A5+14↑j TEXT:54BD tfr a,b TEXT:54BF clra TEXT:54C0 leas 4,s TEXT:54C2 puls pcr,u,y,dpr TEXT:54C2 * End of function sub_54A5 TEXT:54C2 TEXT:54C4 TEXT:54C4 * =============== S U B R O U T I N E ======================================= TEXT:54C4 TEXT:54C4 TEXT:54C4 sub_54C4 * CODE XREF: sub_4C67+63↑P TEXT:54C4 * sub_4C67+87↑P ... TEXT:54C4 pshs dpr,y,u TEXT:54C6 lda $C,s TEXT:54C8 ldx 7,s ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.hex-rays.com/core/disassembler/disassembly-gallery/6809-os9-flex-disassembler.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.