; save interrupts and registers; clear EA
; ....
MOV R1,#0x00      ; command: read IDs
MOV DPTR,#0x0000  ; descriptor: ID of Manufacturer
; map bootloader and reset watchdog if used
; ....
LCALL 0xFFF0      ; invoke Flash API
; here ACC contains returned Manufacturer ID; utilize it if need
; unmap bootloader, reset watchdog again
; restore registers and interrupts