Motorola DSP56303 User Manual page 250

Bootstrap Code
START
clr a #$0a,X0
jclr #2,omr,EPRSCILD
jclr #1,omr,OMR1IS0
jclr #0,omr,I8051HOSTLD; If MC:MB:MA=110, go load from 8051 Host
jmp MC68302HOSTLD
OMR1IS0
jset #0,omr,HC11HOSTLD ; If MC:MB:MA=101, go load from HC11 Host
;=============================================================================
; This is the routine which loads a program through the HI08 host port
; The program is downloaded from the host MCU with the following scenario:
; 1) 3 bytes - Define the program length.
; 2) 3 bytes - Define the address to which to start loading the program to.
; 3) 3n bytes (while n is any integer number)
; The program words will be 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.
; The host MCU may terminate the loading process by setting the HF1=0 and HF0=1.
; When the downloading is terminated, the program will start execution of the
; loaded program from the specified starting address.
; The HI08 boot ROM program enables the following busses to download programs
; through the HI08 port:
;
; 1 - ISA
;
; 2 - HC11
;
; 4 - i8051
;
; 5 - MC68302 - Single strobe non-multiplexed bus with negative strobe
;
;=============================================================================
ISAHOSTLD
movep #%0101000000011000,x:M_HPCR
A-4
; clear a and load X0 with constant 0a0000
; If MC:MB:MA=0xx, go load from EPROM/SCI
; IF MC:MB:MA=10x, go to look for ISA/HC11 options
; If MC:MB:MA=111, go load from MC68302 Host
; If MC:MB:MA=100, go load from ISA HOST
- Dual strobes non-multiplexed bus with negative strobe
pulses dual positive request
- Single strobe non-multiplexed bus with positive strobe
pulse single negative request.
- Dual strobes multiplexed bus with negative strobe pulses
dual negative request.
pulse single negative request.
; Configure the following conditions:
; HAP
; HRP
; HCSP
; HD/HS
; HMUX
; HASP
; meaning in non-multiplexed bus)
; HDSP
; HROD
; spare = 0 This bit should be set to 0 for
; future compatibility
; HEN
; HEN should be cleared
; HAEN
; HREN
; HCSEN = 1 Host chip select input enabled
; HA9EN
DSP56303 User's Manual
= 0 Negative host acknowledge
= 1 Positive host request
= 0 Negative chip select input
= 1 Dual strobes bus (RD and WR strobes)
= 0 Non multiplexed bus
= 0 (address strobe polarity has no
= 0 Negative data strobes polarity
= 0 Host request is active when enabled
= 0 When the HPCR register is modified
= 0 Host acknowledge is disabled
= 1 Host requests are enabled
= 0 (address 9 enable bit has no meaning in