我一直在摆弄ZX Spin模拟器和汇编语言。我曾经在80年代写过BASIC游戏，一直想学习机器代码，但作为一个12岁的孩子太愚蠢了。我已经把这个简单的代码放在一起，它只是创建了一系列组成图像的UDG，并应该将图像打印到屏幕上。我有点卡住了，虽然如何让它使用我的TIT_X_POS和TIT_Y_POS变量，我已经存储和初始化到内存位置。它似乎与DEFB语句中的“_AT”坐标绑定在一起，并且似乎不能向其中传递变量。有人有什么快速提示吗？代码如下：

ORG 30000

    _MAIN 

        CALL SUB_STARTUP
        CALL SUB_PRINT_TIT                                  ;Print TIT sprite
    RET                                                 ;Return to BASIC

    _SUBS 

    SUB_STARTUP

        CALL CLS

        LD A, 0
        LD (TIT_Y_POS), A
        LD A, 25
        LD (TIT_X_POS), A

    RET

    SUB_PRINT_TIT               

        LD HL, TIT_UDGS                                         ;Get location of UDG data.
        LD (UDGPOINTER), HL                                     ;Set UDG SYSVAR pointer.
        LD A, 2                                                 ;Set output channel 2 (upper screen).
        CALL OUTCHAN                                            ;Activate output channel.
        LD DE, TIT_STR                                          ;Start of string.
        LD BC, TIT_STR_END-TIT_STR                              ;Length of string.
    
        ;;;;;;;;;;STUCK HERE - How do I get it to use TIT_Y_POS and TIT_X_POS instead of the _AT values in DEFB?
    
        CALL PRINTSTRING                                    ;Print string.

    RET                                                 ; Return from SUB_PRINT_TIT

    _SYSVARS 

    UDGPOINTER          EQU 23675                           ;UDG pointer.
    TIT_X_POS           EQU 23700                           ;Memory location for X coordinate
    TIT_Y_POS           EQU 23701                           ;Memory location for Y coordinate

    _ROM 

    BORDER              EQU 8859                            ;Set border color.
    CLS                 EQU 3503                            ;Clear screen using attributes in ATTR-P (23693)
    OUTCHAN             EQU 5633                            ;Activate output channel.
    PRINTNUMSMALL           EQU 6683                            ;Print number in BC (9999 max).
    PRINTNUMBIG1            EQU 11563                           ;(1 of 2) to print number in BC (65535 max).
    PRINTNUMBIG2            EQU 11747                           ;(2 of 2) to print number in BC (65535 max).
    PRINTSTRING             EQU 8252                            ;Print string (DE start, BC length).

    _VALUES 

    ;Store values into memory here.

    _STRINGS 

    TIT_STR                                             ;TIT sprite string.

        DEFB _AT, 0, 0, ink, blk, paper, wht, flash, off, bright, off, ua, ub, ue, uf           ;TIT - top
        DEFB _AT, 1, 0,ink, blk, paper, wht, flash, off, bright, off, uc, ud, ug, uh            ;TIT - bottom

    TIT_STR_END EQU $                                       ;Marker for end of string data.

    _CODES EQU $ 

    cr  equ 13                                              ;carriage return.
    ink  equ 16                                             ;INK control code.
    paper  equ 17                                           ;PAPER control code.
    flash  equ 18                                           ;FLASH control code.
    bright  equ 19                                          ;BRIGHT control code.
    inverse equ 20                                          ;INVERSE control code.
    off equ 0                                           ;OFF control code.
    on equ 1                                            ;ON control code.
    _at  equ 22                                             ;AT control code.
    _tab  equ 23                                            ;TAB
    blk  equ 0                                              ;Blk.
    blu  equ 1                                              ;Blue.
    red  equ 2                                              ;Red.
    mag  equ 3                                              ;Magenta.
    grn  equ 4                                              ;Green.
    cyn  equ 5                                              ;Cyan.
    yel  equ 6                                              ;Yellow.
    wht  equ 7                                              ;White.
    ua  equ 144                                             ;UDG "A".
    ub  equ 145                                             ;UDG "B".
    uc  equ 146                                             ;UDG "C".
    ud  equ 147                                             ;UDG "D".
    ue  equ 148                                             ;UDG "E".
    uf  equ 149                                             ;UDG "F".
    ug  equ 150                                             ;UDG "G".
    uh  equ 151                                             ;UDG "H".
    ui  equ 152                                             ;UDG "I".
    uj  equ 153                                             ;UDG "J".
    uk  equ 154                                             ;UDG "K".
    ul  equ 155                                             ;UDG "L".
    um  equ 156                                             ;UDG "M".
    un  equ 157                                             ;UDG "N".
    uo  equ 158                                             ;UDG "O".
    up  equ 159                                             ;UDG "P".
    uq  equ 160                                             ;UDG "Q".
    ur  equ 161                                             ;UDG "R".
    us  equ 162                                             ;UDG "S".
    ut  equ 163                                             ;UDG "Y".
    uu  equ 164                                             ;UDG "U".

    _UDGS ;********************************* UDGS ********************************

    TIT_UDGS                                            ;UDGs.
        ; (A,B)Top-left TIT sprite
        DEFB 15,18,33,41,41,41,33,17, 255,2,1,0,32,16,16,32
        ; (C,D)Bot-left TIT sprite
        DEFB 18,13,0,0,0,1,0,0, 0,255,64,64,64,255,0,0
        ; (E,F)Top-right TIT sprite
        DEFB 255,32,144,72,72,48,0,0, 255,1,2,2,4,8,16,16
        ; (G,H)Bot-right TIT sprite
        DEFB 0,255,2,2,2,255,0,0, 32,192,0,0,0,128,0,0

字符串
提前感谢。