;
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;
|
; romboot.s -- the ROM bootstrap
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; romboot.s -- the ROM bootstrap
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;
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;
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|
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.set termbase,0xF0300000 ; terminal base address
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.set termbase,0xF0300000 ; terminal base address
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.set diskbase,0xF0400000 ; disk base address
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.set diskbase,0xF0400000 ; disk base address
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.set diskbuffer,0xF0480000 ; disk buffer address
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.set diskbuffer,0xF0480000 ; disk buffer address
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.set virtbase,0xC0000000 ; base of kernel virtual addresses
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.set virtbase,0xC0000000 ; base of kernel virtual addresses
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.set virtboot,0xC0000000 ; where to start the bootstrap sector
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.set virtboot,0xC0000000 ; where to start the bootstrap sector
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.set stacktop,0xC0100000 ; where the stack is located
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.set stacktop,0xC0100000 ; where the stack is located
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|
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.set PSW,0
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.set PSW,0
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.set TLB_INDEX,1
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.set TLB_INDEX,1
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.set TLB_ENTRY_HI,2
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.set TLB_ENTRY_HI,2
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.set TLB_ENTRY_LO,3
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.set TLB_ENTRY_LO,3
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.set TLB_ENTRIES,32
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.set TLB_ENTRIES,32
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|
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.code
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.code
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|
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reset:
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reset:
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j start
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j start
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interrupt:
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interrupt:
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j interrupt
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j interrupt
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miss:
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miss:
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j miss
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j miss
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|
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start:
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start:
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mvts $0,PSW ; disable interrupts and user mode
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mvts $0,PSW ; disable interrupts and user mode
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mvts $0,TLB_ENTRY_LO ; invalidate all TLB entries
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mvts $0,TLB_ENTRY_LO ; invalidate all TLB entries
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add $8,$0,virtbase ; by impossible virtual page number
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add $8,$0,virtbase ; by impossible virtual page number
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add $9,$0,$0
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add $9,$0,$0
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add $10,$0,TLB_ENTRIES
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add $10,$0,TLB_ENTRIES
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tlblp:
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tlblp:
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mvts $8,TLB_ENTRY_HI
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mvts $8,TLB_ENTRY_HI
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mvts $9,TLB_INDEX
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mvts $9,TLB_INDEX
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tbwi
|
tbwi
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add $8,$8,0x1000 ; all entries must be different
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add $8,$8,0x1000 ; all entries must be different
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add $9,$9,1
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add $9,$9,1
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bne $9,$10,tlblp
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bne $9,$10,tlblp
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add $29,$0,stacktop ; set stack pointer
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add $29,$0,stacktop ; set stack pointer
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add $4,$0,signon ; show sign-on message
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add $4,$0,signon ; show sign-on message
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jal mout
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jal mout
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cmdlp:
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cmdlp:
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add $4,$0,prompt ; show prompt
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add $4,$0,prompt ; show prompt
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jal mout
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jal mout
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jal echo
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jal echo
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sub $8,$2,0x0D ; '<ret>'?
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sub $8,$2,0x0D ; '<ret>'?
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beq $8,$0,rcmdlp
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beq $8,$0,rcmdlp
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sub $8,$2,'b' ; 'b'?
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sub $8,$2,'b' ; 'b'?
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beq $8,$0,boot
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beq $8,$0,boot
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add $4,$0,'?' ; unknown command
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add $4,$0,'?' ; unknown command
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jal cout
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jal cout
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rcmdlp:
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rcmdlp:
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jal crlf
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jal crlf
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j cmdlp
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j cmdlp
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|
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boot:
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boot:
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jal crlf
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jal crlf
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add $8,$0,diskbase ; check if disk present
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add $8,$0,diskbase ; check if disk present
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add $9,$0,1000000 ; retry count
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add $9,$0,1000000 ; retry count
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boot1:
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boot1:
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ldw $16,$8,0 ; get status
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ldw $16,$8,0 ; get status
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and $10,$16,0x20 ; check if disk ready
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and $10,$16,0x20 ; check if disk ready
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bne $10,$0,boot2 ; ready - exit loop
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bne $10,$0,boot2 ; ready - exit loop
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sub $9,$9,1
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sub $9,$9,1
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bne $9,$0,boot1 ; try again
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bne $9,$0,boot1 ; try again
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j nodsk ; enough retries - error
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j nodsk ; enough retries - error
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boot2:
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boot2:
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ldw $16,$8,12 ; check if capacity greater than 0
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ldw $16,$8,12 ; check if capacity greater than 0
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beq $16,$0,nodsk ; no - report error
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beq $16,$0,nodsk ; no - report error
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add $4,$0,dfmsg ; say that we found a disk
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add $4,$0,dfmsg ; say that we found a disk
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jal mout
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jal mout
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add $4,$16,$0 ; and how many sectors it has
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add $4,$16,$0 ; and how many sectors it has
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jal wout
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jal wout
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add $4,$0,sctmsg
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add $4,$0,sctmsg
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jal mout
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jal mout
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add $8,$0,diskbase ; try to load the boot sector
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add $8,$0,diskbase ; try to load the boot sector
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add $9,$0,1 ; sector count
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add $9,$0,1 ; sector count
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stw $9,$8,4
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stw $9,$8,4
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add $9,$0,0 ; first sector
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add $9,$0,0 ; first sector
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stw $9,$8,8
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stw $9,$8,8
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add $9,$0,1 ; start command
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add $9,$0,1 ; start command
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stw $9,$8,0
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stw $9,$8,0
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dskwt:
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dskwt:
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ldw $9,$8,0
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ldw $9,$8,0
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and $9,$9,0x10 ; done?
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and $9,$9,0x10 ; done?
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beq $9,$0,dskwt
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beq $9,$0,dskwt
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ldw $9,$8,0
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ldw $9,$8,0
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and $9,$9,0x08 ; error?
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and $9,$9,0x08 ; error?
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bne $9,$0,dskerr
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bne $9,$0,dskerr
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add $8,$0,diskbuffer ; copy sector
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add $8,$0,diskbuffer ; copy sector
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add $9,$0,virtboot
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add $9,$0,virtboot
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add $10,$0,512
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add $10,$0,512
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dskcp:
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dskcp:
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ldw $11,$8,0
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ldw $11,$8,0
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stw $11,$9,0
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stw $11,$9,0
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add $8,$8,4
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add $8,$8,4
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add $9,$9,4
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add $9,$9,4
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sub $10,$10,4
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sub $10,$10,4
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bne $10,$0,dskcp
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bne $10,$0,dskcp
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add $8,$0,virtboot ; signature present?
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add $8,$0,virtboot ; signature present?
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ldbu $9,$8,512-2
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ldbu $9,$8,512-2
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sub $9,$9,0x55
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sub $9,$9,0x55
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bne $9,$0,nosig
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bne $9,$0,nosig
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ldbu $9,$8,512-1
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ldbu $9,$8,512-1
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sub $9,$9,0xAA
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sub $9,$9,0xAA
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bne $9,$0,nosig
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bne $9,$0,nosig
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jalr $8 ; finally... lift off
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jalr $8 ; finally... lift off
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j cmdlp ; in case we ever return to here
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j cmdlp ; in case we ever return to here
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|
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nodsk:
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nodsk:
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add $4,$0,dnfmsg ; there is no disk
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add $4,$0,dnfmsg ; there is no disk
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jal mout
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jal mout
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j cmdlp
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j cmdlp
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|
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dskerr:
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dskerr:
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add $4,$0,demsg ; disk error
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add $4,$0,demsg ; disk error
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jal mout
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jal mout
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j cmdlp
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j cmdlp
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nosig:
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nosig:
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add $4,$0,nsgmsg ; no signature
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add $4,$0,nsgmsg ; no signature
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jal mout
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jal mout
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j cmdlp
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j cmdlp
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|
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crlf:
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crlf:
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sub $29,$29,4
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sub $29,$29,4
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stw $31,$29,0
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stw $31,$29,0
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add $4,$0,0x0D
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add $4,$0,0x0D
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jal cout
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jal cout
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add $4,$0,0x0A
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add $4,$0,0x0A
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jal cout
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jal cout
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ldw $31,$29,0
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ldw $31,$29,0
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add $29,$29,4
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add $29,$29,4
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jr $31
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jr $31
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|
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mout:
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mout:
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sub $29,$29,8
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sub $29,$29,8
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stw $31,$29,4
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stw $31,$29,4
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stw $16,$29,0
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stw $16,$29,0
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add $16,$4,$0
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add $16,$4,$0
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mout1:
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mout1:
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ldbu $4,$16,0
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ldbu $4,$16,0
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beq $4,$0,mout2
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beq $4,$0,mout2
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jal cout
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jal cout
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add $16,$16,1
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add $16,$16,1
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j mout1
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j mout1
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mout2:
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mout2:
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ldw $16,$29,0
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ldw $16,$29,0
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ldw $31,$29,4
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ldw $31,$29,4
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add $29,$29,8
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add $29,$29,8
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jr $31
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jr $31
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|
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wout:
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wout:
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sub $29,$29,8
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sub $29,$29,8
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stw $31,$29,4
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stw $31,$29,4
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stw $16,$29,0
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stw $16,$29,0
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add $16,$4,$0
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add $16,$4,$0
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slr $4,$16,16
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slr $4,$16,16
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jal hout
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jal hout
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add $4,$16,$0
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add $4,$16,$0
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jal hout
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jal hout
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ldw $16,$29,0
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ldw $16,$29,0
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ldw $31,$29,4
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ldw $31,$29,4
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add $29,$29,8
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add $29,$29,8
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jr $31
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jr $31
|
|
|
hout:
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hout:
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sub $29,$29,8
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sub $29,$29,8
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stw $31,$29,4
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stw $31,$29,4
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stw $16,$29,0
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stw $16,$29,0
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add $16,$4,$0
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add $16,$4,$0
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slr $4,$16,8
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slr $4,$16,8
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jal bout
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jal bout
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add $4,$16,$0
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add $4,$16,$0
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jal bout
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jal bout
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ldw $16,$29,0
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ldw $16,$29,0
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ldw $31,$29,4
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ldw $31,$29,4
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add $29,$29,8
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add $29,$29,8
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jr $31
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jr $31
|
|
|
bout:
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bout:
|
sub $29,$29,8
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sub $29,$29,8
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stw $31,$29,4
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stw $31,$29,4
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stw $16,$29,0
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stw $16,$29,0
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add $16,$4,$0
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add $16,$4,$0
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slr $4,$16,4
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slr $4,$16,4
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jal nout
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jal nout
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add $4,$16,$0
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add $4,$16,$0
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jal nout
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jal nout
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ldw $16,$29,0
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ldw $16,$29,0
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ldw $31,$29,4
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ldw $31,$29,4
|
add $29,$29,8
|
add $29,$29,8
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jr $31
|
jr $31
|
|
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nout:
|
nout:
|
sub $29,$29,4
|
sub $29,$29,4
|
stw $31,$29,0
|
stw $31,$29,0
|
and $4,$4,0x0F
|
and $4,$4,0x0F
|
add $4,$4,0x30
|
add $4,$4,0x30
|
sub $8,$4,0x3A
|
sub $8,$4,0x3A
|
blt $8,$0,nout1
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blt $8,$0,nout1
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add $4,$4,7
|
add $4,$4,7
|
nout1:
|
nout1:
|
jal cout
|
jal cout
|
ldw $31,$29,0
|
ldw $31,$29,0
|
add $29,$29,4
|
add $29,$29,4
|
jr $31
|
jr $31
|
|
|
cin:
|
cin:
|
add $8,$0,termbase
|
add $8,$0,termbase
|
cin1:
|
cin1:
|
ldw $9,$8,0
|
ldw $9,$8,0
|
and $9,$9,1
|
and $9,$9,1
|
beq $9,$0,cin1
|
beq $9,$0,cin1
|
ldw $2,$8,4
|
ldw $2,$8,4
|
jr $31
|
jr $31
|
|
|
cout:
|
cout:
|
add $8,$0,termbase
|
add $8,$0,termbase
|
cout1:
|
cout1:
|
ldw $9,$8,8
|
ldw $9,$8,8
|
and $9,$9,1
|
and $9,$9,1
|
beq $9,$0,cout1
|
beq $9,$0,cout1
|
stw $4,$8,12
|
stw $4,$8,12
|
jr $31
|
jr $31
|
|
|
echo:
|
echo:
|
sub $29,$29,4
|
sub $29,$29,4
|
stw $31,$29,0
|
stw $31,$29,0
|
jal cin
|
jal cin
|
add $4,$0,$2
|
add $4,$0,$2
|
jal cout
|
jal cout
|
ldw $31,$29,0
|
ldw $31,$29,0
|
add $29,$29,4
|
add $29,$29,4
|
jr $31
|
jr $31
|
|
|
signon:
|
signon:
|
.byte 0x0D, 0x0A
|
.byte 0x0D, 0x0A
|
.byte "ROM Bootstrap Version 1"
|
.byte "ROM Bootstrap Version 1"
|
.byte 0x0D, 0x0A, 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0x0D, 0x0A, 0
|
|
|
prompt:
|
prompt:
|
.byte "#"
|
.byte "#"
|
.byte 0
|
.byte 0
|
|
|
dnfmsg:
|
dnfmsg:
|
.byte "Disk not found!"
|
.byte "Disk not found!"
|
.byte 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0
|
|
|
dfmsg:
|
dfmsg:
|
.byte "Disk with 0x"
|
.byte "Disk with 0x"
|
.byte 0
|
.byte 0
|
|
|
sctmsg:
|
sctmsg:
|
.byte " sectors found, booting..."
|
.byte " sectors found, booting..."
|
.byte 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0
|
|
|
demsg:
|
demsg:
|
.byte "Disk error!"
|
.byte "Disk error!"
|
.byte 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0
|
|
|
nsgmsg:
|
nsgmsg:
|
.byte "MBR signature missing!"
|
.byte "MBR signature missing!"
|
.byte 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0
|
|
|
