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[/] [eco32/] [trunk/] [simtest/] [rom/] [romboot.s] - Blame information for rev 149

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Line No. Rev Author Line
1 9 hellwig
;
2
; romboot.s -- the ROM bootstrap
3
;
4
 
5
        .set    termbase,0xF0300000     ; terminal base address
6
        .set    diskbase,0xF0400000     ; disk base address
7
        .set    diskbuffer,0xF0480000   ; disk buffer address
8
        .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    stacktop,0xC0100000     ; where the stack is located
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12
        .set    PSW,0
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        .set    TLB_INDEX,1
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        .set    TLB_ENTRY_HI,2
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        .set    TLB_ENTRY_LO,3
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        .set    TLB_ENTRIES,32
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18
        .code
19
 
20
reset:
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        j       start
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23
interrupt:
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        j       interrupt
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26
miss:
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        j       miss
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29
start:
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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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        add     $8,$0,virtbase           ; by impossible virtual page number
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        add     $9,$0,$0
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        add     $10,$0,TLB_ENTRIES
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tlblp:
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        mvts    $8,TLB_ENTRY_HI
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        mvts    $9,TLB_INDEX
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        tbwi
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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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        bne     $9,$10,tlblp
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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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        jal     mout
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cmdlp:
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        add     $4,$0,prompt             ; show prompt
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        jal     mout
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        jal     echo
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        sub     $8,$2,0x0D              ; '<ret>'?
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        beq     $8,$0,rcmdlp
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        sub     $8,$2,'b'               ; 'b'?
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        beq     $8,$0,boot
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        add     $4,$0,'?'                ; unknown command
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        jal     cout
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rcmdlp:
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        jal     crlf
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        j       cmdlp
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boot:
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        jal     crlf
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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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boot1:
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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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        bne     $10,$0,boot2             ; ready - exit loop
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        sub     $9,$9,1
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        bne     $9,$0,boot1              ; try again
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        j       nodsk                   ; enough retries - error
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boot2:
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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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        add     $4,$0,dfmsg              ; say that we found a disk
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        jal     mout
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        add     $4,$16,$0                ; and how many sectors it has
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        jal     wout
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        add     $4,$0,sctmsg
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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     $9,$0,1                  ; sector count
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        stw     $9,$8,4
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        add     $9,$0,0                   ; first sector
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        stw     $9,$8,8
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        add     $9,$0,1                  ; start command
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        stw     $9,$8,0
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dskwt:
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        ldw     $9,$8,0
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        and     $9,$9,0x10              ; done?
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        beq     $9,$0,dskwt
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        ldw     $9,$8,0
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        and     $9,$9,0x08              ; error?
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        bne     $9,$0,dskerr
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        add     $8,$0,diskbuffer ; copy sector
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        add     $9,$0,virtboot
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        add     $10,$0,512
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dskcp:
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        ldw     $11,$8,0
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        stw     $11,$9,0
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        add     $8,$8,4
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        add     $9,$9,4
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        sub     $10,$10,4
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        bne     $10,$0,dskcp
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        add     $8,$0,virtboot           ; signature present?
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        ldbu    $9,$8,512-2
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        sub     $9,$9,0x55
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        bne     $9,$0,nosig
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        ldbu    $9,$8,512-1
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        sub     $9,$9,0xAA
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        bne     $9,$0,nosig
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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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nodsk:
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        add     $4,$0,dnfmsg             ; there is no disk
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        jal     mout
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        j       cmdlp
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dskerr:
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        add     $4,$0,demsg              ; disk error
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        jal     mout
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        j       cmdlp
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nosig:
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        add     $4,$0,nsgmsg             ; no signature
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        jal     mout
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        j       cmdlp
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crlf:
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        sub     $29,$29,4
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        stw     $31,$29,0
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        add     $4,$0,0x0D
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        jal     cout
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        add     $4,$0,0x0A
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        jal     cout
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        ldw     $31,$29,0
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        add     $29,$29,4
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        jr      $31
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mout:
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        sub     $29,$29,8
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        stw     $31,$29,4
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        stw     $16,$29,0
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        add     $16,$4,$0
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mout1:
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        ldbu    $4,$16,0
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        beq     $4,$0,mout2
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        jal     cout
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        add     $16,$16,1
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        j       mout1
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mout2:
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        ldw     $16,$29,0
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        ldw     $31,$29,4
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        add     $29,$29,8
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        jr      $31
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wout:
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        sub     $29,$29,8
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        stw     $31,$29,4
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        stw     $16,$29,0
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        add     $16,$4,$0
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        slr     $4,$16,16
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        jal     hout
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        add     $4,$16,$0
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        jal     hout
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        ldw     $16,$29,0
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        ldw     $31,$29,4
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        add     $29,$29,8
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        jr      $31
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hout:
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        sub     $29,$29,8
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        stw     $31,$29,4
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        stw     $16,$29,0
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        add     $16,$4,$0
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        slr     $4,$16,8
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        jal     bout
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        add     $4,$16,$0
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        jal     bout
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        ldw     $16,$29,0
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        ldw     $31,$29,4
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        add     $29,$29,8
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        jr      $31
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bout:
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        sub     $29,$29,8
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        stw     $31,$29,4
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        stw     $16,$29,0
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        add     $16,$4,$0
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        slr     $4,$16,4
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        jal     nout
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        add     $4,$16,$0
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        jal     nout
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        ldw     $16,$29,0
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        ldw     $31,$29,4
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        add     $29,$29,8
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        jr      $31
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nout:
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        sub     $29,$29,4
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        stw     $31,$29,0
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        and     $4,$4,0x0F
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        add     $4,$4,0x30
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        sub     $8,$4,0x3A
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        blt     $8,$0,nout1
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        add     $4,$4,7
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nout1:
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        jal     cout
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        ldw     $31,$29,0
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        add     $29,$29,4
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        jr      $31
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cin:
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        add     $8,$0,termbase
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cin1:
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        ldw     $9,$8,0
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        and     $9,$9,1
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        beq     $9,$0,cin1
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        ldw     $2,$8,4
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        jr      $31
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cout:
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        add     $8,$0,termbase
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cout1:
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        ldw     $9,$8,8
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        and     $9,$9,1
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        beq     $9,$0,cout1
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        stw     $4,$8,12
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        jr      $31
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echo:
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        sub     $29,$29,4
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        stw     $31,$29,0
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        jal     cin
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        add     $4,$0,$2
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        jal     cout
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        ldw     $31,$29,0
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        add     $29,$29,4
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        jr      $31
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signon:
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        .byte   0x0D, 0x0A
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        .byte   "ROM Bootstrap Version 1"
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        .byte   0x0D, 0x0A, 0x0D, 0x0A, 0
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prompt:
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        .byte   "#"
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        .byte   0
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dnfmsg:
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        .byte   "Disk not found!"
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        .byte   0x0D, 0x0A, 0
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253
dfmsg:
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        .byte   "Disk with 0x"
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        .byte   0
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257
sctmsg:
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        .byte   " sectors found, booting..."
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        .byte   0x0D, 0x0A, 0
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demsg:
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        .byte   "Disk error!"
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        .byte   0x0D, 0x0A, 0
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nsgmsg:
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        .byte   "MBR signature missing!"
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        .byte   0x0D, 0x0A, 0

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