Added an example of calculating Fibonacci numbers.

The maximum possible number of a number in the sequence is 47.
It is limited to the 32-bit value of numbers.
The result is displayed in hexadecimal value, since it is very
difficult to implement the conversion of such large numbers to
decimal representation (ASCII) without hardware division.

rom/fibo.rom

@@ -0,0 +1,2 @@
+v2.0 raw
+38 2F 0C 0A 53 74 61 72 74 69 6E 67 20 6C 6F 61 64 69 6E 67 20 74 68 65 20 46 69 62 6F 6E 61 63 63 69 20 70 72 6F 67 72 61 6D 2E 2E 2E 0A 24 4C 06 03 0E 01 2E 0C 36 03 2A 04 A8 2A 07 06 02 4E 16 02 1E 00 26 01 2E 0D 36 00 2A 07 38 E7 0D 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 AB 0A 45 6E 74 65 72 20 74 68 65 20 64 65 73 69 72 65 64 20 46 69 62 6F 20 6E 75 6D 62 65 72 20 28 32 20 74 6F 20 34 37 29 3A 20 24 16 20 A8 2E 0C 36 80 F8 30 11 48 32 0D 36 84 3E 01 36 88 3E 10 22 3C 0A 40 4B 0D 04 30 38 4F 0D 14 0A 04 41 22 C7 1E 00 0E 0A 16 00 14 10 60 60 0D 10 38 57 0D 04 10 39 41 0D 44 18 C2 3C 10 40 55 0D 39 41 0D 44 18 21 68 7F 0D 30 48 7B 0D 28 C7 38 55 0D 4E 06 01 16 01 2A 04 19 48 7F 0D 22 44 4C 54 5C 64 05 16 04 2E 0C 1E 80 26 84 F4 C7 CF F3 8F F9 F4 F8 18 20 11 48 99 0D 66 5E 56 4E 46 22 44 54 06 01 16 01 2A 04 56 46 22 0E 0A 39 AD 0D 22 4C 54 5C 64 26 00 30 48 C9 0D 28 D7 30 48 CF 0D 28 C7 14 30 C8 A8 1E 0A 84 19 48 D6 0D 81 E0 11 48 CA 0D C4 66 5E 56 4E 22 39 2B 0D 06 03 0E 01 2E 0D 36 00 2A 04 06 0C 0E 04 2E 0C 36 88 2A 05 2E 0C 36 88 39 BE 0D D0 11 39 8B 0D 0E 2E 39 AD 0D 11 48 07 0E 39 B8 0D 2E 0C 36 84 0E 30 39 AD 0D 0E 78 39 AD 0D 26 04 39 50 0D 39 B8 0D 38 E7 0D FF

src/fibo.asm

@@ -0,0 +1,307 @@
+org 0C00h
+jmp loader
+
+loader_msg:
+    db 0Ah, "Starting loading the Fibonacci program...", 0Ah, "$"
+
+loader:
+    push b
+
+    mov a, 3
+    mov b, 1
+    mov h, (loader_msg >> 8)
+    mov l, (loader_msg & 255)
+    int 4h
+
+    xor a, a
+    int 7h      ; reset storage system to copy
+
+    mov a, 2    ; read the second sector to RAM
+    pop b       ; storage number
+    mov c, 2    ; count of sectors to read
+    mov d, 0
+    mov e, 1
+    mov h, 0Dh
+    mov l, 00h
+    int 7h
+
+    jmp start
+
+padding:
+    ; db 176 dup 0    ; pad
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+signature:
+    db 0ABh         ; boot signature
+
+intro:
+    db 0Ah, "Enter the desired Fibo number (2 to 47): ", "$"
+
+num_a equ 0C80h
+num_b equ 0C84h
+kb_buf equ 0C88h
+KB_BUF_SIZE equ 16
+
+SETUP proc
+        mov c, (16 + KB_BUF_SIZE)
+        xor a, a    ; (A)=0
+
+        mov h, (num_a >> 8)
+        mov l, (num_a & 255)
+    set_loop:
+        mov mem, a
+        inc l
+        dec c
+        jnz set_loop
+
+        mov l, (num_b & 255)
+        mov mem, 01h    ; num_b = 1
+        mov l, (kb_buf & 255)
+        mov mem, KB_BUF_SIZE    ; set buffer max size
+
+        ret
+SETUP endp
+
+DIG_TO_HEX proc
+    ; (A) - digit to convert from num to HEX ASCII
+        cmp a, 10
+        jnc hex_conv_alpha  ; a >= 10
+    hex_conv_dig:
+        add a, '0'  ; a < 10
+        jmp hex_conv
+    hex_conv_alpha: ; a >= 10
+        sub a, 10
+        add a, 'A'
+    hex_conv:
+        ret
+DIG_TO_HEX endp
+
+PRINT_HEX proc
+    ; (H)(L) - address of number
+    ; (E) - number of bytes
+
+        mov a, mem
+        mov d, 0    ; cnt of digits
+        mov b, 10
+
+    hex_prep:
+        mov c, 0    ; remainder
+
+    hex_loop:
+        sub a, 16   ; eq div by 16
+        jc hex_save_ord
+        inc c
+        jmp hex_loop
+
+    hex_save_ord:
+        add a, 16   ; return digit to positive
+
+        call DIG_TO_HEX
+        push a  ; save digit
+        inc d
+
+        mov a, c
+        cmp a, 16
+        jnc hex_prep    ; jmp if remainder >= 16
+
+        call DIG_TO_HEX
+        push a  ; save digit
+        inc d
+
+        dec e
+        jz hex_print_loop
+        inc l
+        jnz hex1
+        inc h
+    hex1:
+        mov a, mem
+        jmp hex_prep
+
+    hex_print_loop:
+        pop b
+        mov a, 1
+        mov c, 1
+        int 4h
+        dec d
+        jnz hex_print_loop
+
+        ret
+PRINT_HEX endp
+
+ADD_UI32 proc
+    ; Realization the next sequence:
+    ;     t = a + b
+    ;     a = b
+    ;     b = t
+    ; or short:
+    ;     a, b = b, a + b
+    add_start:
+        push a
+        push b
+        push c
+        push d
+        push e
+
+        clc     ; clear carry flag
+        mov c, 04h  ; counter for 32bit numbers
+        mov h, (num_a >> 8) ; constant value
+
+        mov d, (num_a & 255)
+        mov e, (num_b & 255)
+
+    add_loop:
+        mov l, e
+        mov a, mem  ; t = b
+        mov b, mem  ; tb = b
+        mov l, d
+        adc a, mem  ; t = t(b) + a
+        mov mem, b  ; a = tb(b)
+        mov l, e
+        mov mem, a  ; b = t
+
+        inc d
+        inc e
+        dec c
+        jnz add_loop
+
+    add_end:
+        pop e
+        pop d
+        pop c
+        pop b
+        pop a
+
+        ret
+ADD_UI32 endp
+
+putc proc
+    ; (B) Char to write
+    push a
+    push c
+
+    mov a, 1
+    mov c, 1
+    int 4h
+
+    pop c
+    pop a
+
+    ret
+putc endp
+
+put_nl proc
+    mov b, 0Ah
+    call putc   ; new line
+    ret
+put_nl endp
+
+atoi proc
+    ; (H)(L) - address of string buffer by INT5
+    ; The string must contain only ASCII digits!
+    ; (A) - result return
+        push b
+        push c
+        push d
+        push e
+
+    atoi0:
+        mov e, 0    ; result
+        inc l
+        jnz atoi1
+        inc h
+
+    atoi1:
+        mov c, mem  ; string length
+    atoi1_loop:
+        inc l
+        jnz atoi2
+        inc h
+
+    atoi2:
+        mov a, mem
+        sub a, '0'
+        mov b, a
+
+        xor a, a
+        mov d, 10
+    atoi3_mult:
+        add a, e
+        dec d
+        jnz atoi3_mult   ; multiple by 10
+
+        add a, b
+        mov e, a    ; save result
+
+    atoi4:
+        dec c
+        jnz atoi1_loop
+
+    atoi_end:
+        mov a, e
+        pop e
+        pop d
+        pop c
+        pop b
+
+        ret
+atoi endp
+
+start:
+    call SETUP
+
+    mov a, 3
+    mov b, 1
+    mov h, (intro >> 8)
+    mov l, (intro & 255)
+    int 4h  ; print intro string
+
+    ; get desired fibo number (2 to 47) (int5 A=4, clear buffer before (A=12))
+    mov a, 0Ch
+    mov b, 4
+    mov h, (kb_buf >> 8)
+    mov l, (kb_buf & 255)
+    int 5h
+
+    mov h, (kb_buf >> 8)
+    mov l, (kb_buf & 255)
+    call atoi
+    mov c, a
+    dec c
+
+fibo:
+    call ADD_UI32
+
+    mov b, '.'
+    call putc   ; put dot for each set
+
+    dec c
+    jnz fibo
+
+    call put_nl ; new line
+
+result:
+    mov h, (num_b >> 8)
+    mov l, (num_b & 255)
+
+    mov b, "0"
+    call putc
+    mov b, "x"
+    call putc
+
+    mov e, 4
+    call PRINT_HEX
+
+    call put_nl ; new line
+
+    jmp start
+
+    hlt