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Sepp J Morris 31738079c4 Upload
Digital Research
2020-11-06 18:50:37 +01:00

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;*****************************************************************
; *
; VIRTUAL SCREEN STRUCTURES AND EQUATES *
; *
;*****************************************************************
backsp equ 08H
escape equ 01bH
blank equ ' '
crt_col equ 80 ; screen sizings
crt_row equ 24
crt_size equ crt_col * crt_row
crtfull equ 0
; Screen Structure
vs_cursor equ word ptr 0[bx] ; cursor pts to attrib and char
vs_oldcursor equ word ptr 2[bx]
vs_column equ byte ptr 4[bx]
vs_row equ byte ptr 5[bx]
vs_mode equ byte ptr 6[bx] ; screen mode - see vsm values
vs_attrib equ byte ptr 7[bx]
vs_xy equ word ptr 8[bx] ; x-y coordinates for direct
vs_old_xy equ word ptr 0aH[bx] ; cursor positioning
vs_screen_seg equ word ptr 0cH[bx] ; for screen image buffer
vs_escape_rt equ word ptr 0eH[bx] ; escape routine to ret to
vs_struc_len equ 010h ; edge up to pp. boundary
; attribute bit values
vsa_reverse equ 01110000B ; IBM PC compatible
vsa_normal equ 00000111B
vsa_blink equ 10000000B
vsa_bright equ 00001000B
; mode bit values
vsm_no_wrap equ 00000010B ; CCP/M only
vsm_nocursor equ 00000100B
vccb_pcon equ 0ah
vccb_vcon equ 0bh