Motorola DSP56309 User Manual page 321

Bootstrap Programs
; BOOTSTRAP CODE FOR DSP56309 - (C) Copyright 1997 Motorola Inc.
; Revised March, 18 1997.
;
; Bootstrap through the Host Interface, External EPROM or SCI.
;
; This is the Bootstrap program contained in the DSP56309 192-word Boot
; ROM. This program can load any program RAM segment from an external
; EPROM, from the Host Interface or from the SCI serial interface.
;
;
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; If MD:MC:MB:MA=x000, then the Boot ROM is bypassed and the DSP56309
; will start fetching instructions beginning with address $C00000 (MD=0)
; or $008000 (MD=1) assuming that an external memory of SRAM type is
; used. The accesses will be performed using 31 wait states with no
; address attributes selected (default area).
;
;
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; Operation modes MD:MC:MB:MA=0001-0111 are reserved.
;
;
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; If MD:MC:MB:MA=1001, then it loads a program RAM segment from consecutive
; byte-wide P memory locations, starting at P:$D00000 (bits 7-0).
; The memory is selected by the Address Attribute AA1 and is accessed with
; 31 wait states.
; The EPROM bootstrap code expects to read 3 bytes
; specifying the number of program words, 3 bytes specifying the address
; to start loading the program words and then 3 bytes for each program
; word to be loaded. The number of words, the starting address and the
; program words are read least significant byte first followed by the
; mid and then by the most significant byte.
; The program words will be condensed into 24-bit words and stored in
; contiguous PRAM memory locations starting at the specified starting address.
; After reading the program words, program execution starts from the same
; address where loading started.
;
;
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; If MD:MC:MB:MA=1010, then it loads the program RAM from the SCI interface.
; The number of program words to be loaded and the starting address must
; be specified. The SCI bootstrap code expects to receive 3 bytes
; specifying the number of program words, 3 bytes specifying the address
; to start loading the program words and then 3 bytes for each program
; word to be loaded. The number of words, the starting address and the
; program words are received least significant byte first followed by the
; mid and then by the most significant byte. After receiving the
; program words, program execution starts in the same address where
; loading started. The SCI is programmed to work in asynchronous mode
; with 8 data bits, 1 stop bit and no parity. The clock source is
; external and the clock frequency must be 16x the baud rate.
; After each byte is received, it is echoed back through the SCI
A-2 DSP56309UM/D MOTOROLA