;ASC for the IBM Personal Computer - 1986 by Jeff Prosise ; kb_data equ 60h ;keyboard data port kb_ctrl equ 61h ;keyboard control port eoi equ 20h ;8259 end-of-interrupt value int_ctrl_port equ 20h ;8259 PIC port a_key equ 30 ;scan code for 'A' key alt_key equ 8 ;shift code for Alt key ; bios_data segment at 40h ;BIOS data area org 63h addr_6845 dw ? ;6845 Index Register address bios_data ends ; code segment para public 'code' assume cs:code org 100h begin: jmp initialize ;jump to initialization code ; notice db 'Copyright 1986 Ziff-Davis Publishing Co.' notice2 db 'Programmed by Jeff Prosise ' ibm_signature db 'IBM' ;EGA BIOS signature adapter db 2 ;0 = CGA, 1 = MDA, 2 = EGA video_segment dw 0B800h ;video segment address video_page db ? ;current video page border_attr db 0Fh ;window border attribute text_attr db 1Fh ;window text attribute header_attr db 1Eh ;window header attribute window_row db 1 ;row of left corner of window window_column db 3 ;column of left corner of window start_value db 0 ;first value in ASCII table int_status db 0 ;status of interrupt routine cursor_mode dw ? ;cursor scan line definition old_int_9h label dword ;old interrupt vector old_keyboard_int dw 2 dup (?) screen_buffer dw offset initialize ;pointer to screen buffer area ; enable_values db 2Ch,28h,2Dh,29h, ;values to enable CGA display db 2Ah,2Eh,1Eh header_text db ' Dec Hex Char Dec Hex Char ' ;window header text ; ;----------------------------------------------------------------------------- ;Front-end routine for the keyboard interrupt handler. Execution is vectored ;here whenever an interrupt 9 is generated by the PC keyboard. ;----------------------------------------------------------------------------- ascview proc near cmp int_status,0 ;is ASCII table already displayed? jne short_exit ;yes, then exit immediately sti ;enable interrupts push ax ;save registers push bx push cx push dx push si push di push ds push es in al,kb_data ;get scan code from keyboard cmp al,a_key ;was the 'A' key pressed? jne exit ;no, then exit to normal routine mov ah,2 ;get state of shift keys int 16h test al,alt_key ;is the Alt key depressed? jne asc1 ;yes, then continue ; ;Exit is achieved thru here when execution is to be transferred to the normal ;BIOS keyboard interrupt handling routine. ; exit: pop es ;restore registers pop ds pop di pop si pop dx pop cx pop bx pop ax short_exit: jmp old_int_9h ;goto BIOS keyboard routine ; ;The key combination Alt-A was just pressed. Reset the keyboard and issue an ;EOI to the 8259 PIC to enable hardware interrupts. ; asc1: call kb_reset ;reset keyboard, end 8259 int push cs ;set DS and ES to the code segment pop ds push cs pop es assume ds:code ; ;Check the current video mode to see if it's one of the 80-column text modes ;(2, 3, or 7). If it is, then continue. If it's not, gracefully abort this ;routine by exiting thru an IRET. ; mov ah,15 ;get video page and display mode int 10h cmp al,2 ;video mode 2? je asc2 ;yes, then continue cmp al,3 ;mode 3? je asc2 ;yes, then continue cmp al,7 ;mode 7 (monochrome)? je asc2 ;yes, then continue done: pop es ;restore register values for exit pop ds pop di pop si pop dx pop cx pop bx pop ax iret ;return to interrupted program ; ;Save the current video page number and the cursor scan line parameters, ;set the interrupt routine status flag, and blank the cursor. ; asc2: mov video_page,bh ;save page number mov int_status,1 ;set interrupt routine status flag mov ah,3 ;get the cursor shape int 10h mov cursor_mode,cx ;save it mov ah,1 ;hide the cursor for now mov ch,20h int 10h ; ;Save the contents of the portion of the screen that will underlie the window. ; cmp adapter,0 ;is this a CGA? jne asc3 ;no, then skip disable call disable_cga ;disable CGA video asc3: mov di,screen_buffer ;point DI to storage buffer call save_screen ;save screen contents ; ;Pop the window border onto the display by writing directly to video. Finish ;things up by filling the blank window with the text of the ASCII table. ; call open_window ;pop up the window border cmp adapter,0 ;is this a CGA? jne asc4 ;no, then skip enable call enable_cga ;enable CGA video asc4: call fill_window ;write the window text ; ;The window is now displayed on the screen. Wait for a keypress. ; asc5: mov ah,0 ;get a keypress int 16h cmp al,0 ;is it an extended code? je asc10 ;yes, then jump cmp al,27 ;ESC key pressed? jne asc5 ;no, then get another keypress ; ;The ESC key has been pressed. Restore the original contents of the screen, ;restore the cursor, reset the status flag, and exit to the application. ; cmp adapter,0 ;blank video if CGA installed jne asc6 call disable_cga asc6: mov si,screen_buffer ;point SI to holding buffer call restore_screen ;restore video memory contents cmp adapter,0 ;enable video if necessary jne asc7 call enable_cga asc7: mov ah,1 ;unblank the cursor mov cx,cursor_mode ;define cursor scan lines int 10h mov int_status,0 ;reset status flag jmp done ;exit ; ;A key has been pressed that returned an extended code. ; asc10: cmp ah,72 ;Up-Arrow pressed? jne asc11 ;no, then jump to next test call scroll_down ;yes, then scroll down jmp asc5 ;return for another keypress asc11: cmp ah,80 ;Down-Arrow pressed? jne asc12 call scroll_up ;scroll window up jmp asc5 asc12: cmp ah,73 ;PgUp pressed? jne asc13 call last_window_page ;flip window page back jmp asc5 asc13: cmp ah,81 ;PgDn pressed? jne asc14 call next_window_page ;flip window page forward jmp asc5 asc14: cmp ah,79 ;End pressed? jne asc15 call end_window_page ;flip to last window page jmp asc5 asc15: cmp ah,71 ;Home pressed? jne asc16 ;no, then start again call first_window_page ;goto first window page asc16: jmp asc5 ;look for another keypress ascview endp ; ;----------------------------------------------------------------------------- ;SAVE_SCREEN saves the contents of the screen beneath the window. ;Entry: ES:DI - buffer address ;----------------------------------------------------------------------------- save_screen proc near mov dh,window_row ;row and column of window corner mov dl,window_column mov bl,video_page ;get video page in BX xor bh,bh push di ;save buffer address call video_offset ;get starting address of window mov si,di ;transfer address to SI pop di ;retrieve buffer address push ds ;save DS mov ds,video_segment ;set DS to video segment assume ds:nothing mov cx,19 ;19 lines to save cld ;clear DF save1: push cx ;save line counter mov cx,30 ;30 words per line rep movsw ;transfer one line to buffer add si,100 ;adjust SI for next line pop cx ;get line count loop save1 ;loop until done pop ds ;restore DS assume ds:code ret save_screen endp ; ;----------------------------------------------------------------------------- ;RESTORE_SCREEN restores the contents of the screen beneath the window. ;Entry: DS:SI - buffer address ;----------------------------------------------------------------------------- restore_screen proc near mov dh,window_row ;row & column where window starts mov dl,window_column mov bl,video_page ;get video page in BX xor bh,bh call video_offset ;get window starting address mov es,video_segment ;set ES to video segment mov cx,19 ;19 lines to restore cld ;clear DF restore1: push cx ;save line counter mov cx,30 ;30 words per line rep movsw ;restore one line add di,100 ;set DI for next line pop cx ;retrieve count loop restore1 ;loop until done ret restore_screen endp ; ;----------------------------------------------------------------------------- ;VIDEO_OFFSET calculates the offset address in video memory that corresponds ;to the given row, column, and video page. ;Entry: DH,DL - row, column | Exit: DI - offset ; BX - video page | ;----------------------------------------------------------------------------- video_offset proc near mov al,160 ;row * 160 mul dh ;result in AX shl dl,1 ;column * 2 xor dh,dh ;byte to word in DX add ax,dx ;add the two mov di,ax ;save result in DI mov ax,1000h ;length of one video page mul bx ;page * 1000h add di,ax ;complete the offset address ret video_offset endp ; ;----------------------------------------------------------------------------- ;DISABLE_CGA and ENABLE_CGA routines disable and enable CGA video by writing ;to the Mode Select Register at port address 3D8h. ;----------------------------------------------------------------------------- disable_cga proc near mov dx,3DAh ;load Status Register address disable1: in al,dx ;get video status test al,8 ;vertical retrace active? je disable1 ;no, then wait until it is sub dx,2 ;load MSR address mov al,25h ;value to disable video out dx,al ;send it to the adapter ret disable_cga endp ; enable_cga proc near mov ah,15 ;get current video mode int 10h lea bx,enable_values ;offset of enable value table xlat ;get the value to enable video mov dx,3D8h ;load address of MSR out dx,al ;OUT the enable value ret enable_cga endp ; ;----------------------------------------------------------------------------- ;KB_RESET resets the keyboard and issues an EOI to the 8259 PIC. ;----------------------------------------------------------------------------- kb_reset proc near in al,kb_ctrl ;get current control port value mov ah,al ;save it in AH or al,80h ;set bit 7 out kb_ctrl,al ;send reset value mov al,ah ;get original value out kb_ctrl,al ;send it out to enable keyboard cli ;suspend interrupts mov al,eoi ;get EOI value out int_ctrl_port,al ;send EOI to 8259 sti ;enable interrupts ret kb_reset endp ; ;----------------------------------------------------------------------------- ;BIN2ASC outputs a byte value to the screen in decimal or hexadecimal form. ;Entry: DH,DL - row, column ; AL - number to output ; BL - divisor (10 for decimal output, 16 for hex) ;----------------------------------------------------------------------------- bin2asc proc near push ax ;save value to output xor cx,cx ;zero digit counter xor ah,ah ;byte to word in AX bin1: div bl ;divide AX by 10 or 16 push ax ;save AH (remainder) inc cx ;increment counter xor ah,ah ;byte to word (quotient) or al,al ;was the quotient zero? jne bin1 ;no, then go back for more bin2: pop ax ;get digit to print next mov al,ah ;put it in AL or al,48 ;convert binary to ASCII cmp al,'9' ;alphanumeric hex digit? jna bin3 ;no, then jump ahead add al,7 ;yes, then more conversion needed bin3: mov ah,text_attr ;set text attribute for write call output_char ;print the digit inc dl ;advance cursor loop bin2 ;loop until done pop ax ;restore value of AX ret bin2asc endp ; ;----------------------------------------------------------------------------- ;OUTPUT_CHAR writes the designated character directly to video memory. ;Entry: DH,DL - row, column ; AH,AL - attribute, character ;----------------------------------------------------------------------------- output_char proc near push dx ;save DX and AX push ax mov bl,video_page ;get page in BX xor bh,bh call video_offset ;calculate address to write to cmp adapter,0 ;is this a CGA? jne output3 ;no, then skip wait loop mov dx,3DAh ;get CGA Status Register address output1: in al,dx ;wait until horiz. retrace done test al,1 jne output1 cli ;suspend interrupts during write output2: in al,dx ;wait for next horizontal retrace test al,1 je output2 output3: pop ax ;get character and attribute stosw ;write them to video memory sti ;enable interrupts pop dx ;restore DX ret output_char endp ; ;----------------------------------------------------------------------------- ;FILL_WINDOW writes the text of the ASCII table to the window. ;----------------------------------------------------------------------------- fill_window proc near mov dh,window_row ;set DH for first text row add dh,2 mov al,start_value ;get first table value in AL mov cx,16 ;16 lines to fill fill1: push cx ;save line counter mov dl,window_column ;specify starting column add dl,2 call write_line ;write first half of the line add dl,5 ;advance cursor for next half add al,16 ;adjust AL for next half call write_line ;write second half sub al,15 ;set AL for start of next line inc dh ;set cursor for next row pop cx ;retrieve line counter loop fill1 ;loop until table full ret fill_window endp ; ;----------------------------------------------------------------------------- ;WRITE_LINE outputs one ASCII character and its decimal and hex equivalents. ;Entry: AL - ASCII code for character to output ; DH,DL - row, column to start writing at ;----------------------------------------------------------------------------- write_line proc near mov es,video_segment ;set ES to video for writing cmp al,100 ;advance cursor if AL < 100 jae write1 inc dl cmp al,10 ;advance again if AL < 10 jae write1 inc dl write1: mov bl,10 ;set BL for decimal output call bin2asc ;output decimal text add dl,2 ;set cursor to next field cmp al,10h ;advance cursor if AL < 10h jae write2 inc dl write2: mov bl,16 ;set BL for hex output call bin2asc ;output hexadecimal text add dl,2 ;goto next field mov ah,text_attr ;set text attribute call output_char ;print the character ret write_line endp ; ;----------------------------------------------------------------------------- ;OPEN_WINDOW draws the window border onto the screen. Character/attribute ;pairs are sent directly to video memory for fast display speed. ;----------------------------------------------------------------------------- open_window proc near mov dh,window_row ;get coordinates of window corner mov dl,window_column mov es,video_segment ;point ES to video buffer cld ;clear DF for string operations mov bl,video_page ;get video page in BX xor bh,bh call video_offset ;calculate starting address ; ;Write the top line of the window border to video. ; mov al,218 ;start with upper left corner mov ah,border_attr ;set attribute stosw mov cx,28 ;do the next 28 characters mov al,196 rep stosw mov al,191 ;do upper right corner stosw ; ;Do the window header line. ; add di,100 ;set DI for new line mov al,179 ;left window border character stosw ;write it lea si,header_text ;point SI to text of line mov cx,28 ;28 characters to write mov ah,header_attr ;use header attribute for these open1: lodsb ;get the text character stosw ;write char/attr pair to video loop open1 ;repeat for all 28 mov ah,border_attr ;do rightmost column mov al,179 stosw ; ;Now write the next 16 lines (no text) to the display. ; add di,100 ;set DI for new line mov cx,16 ;16 lines to do open2: push cx ;save line counter mov al,179 ;do leftmost column mov ah,border_attr stosw mov al,32 ;do next 28 columns (blank) mov ah,text_attr mov cx,28 rep stosw mov al,179 ;do rightmost column mov ah,border_attr stosw add di,100 ;adjust DI for next line pop cx ;retrieve counter loop open2 ;loop until finished ; ;Finish things up by writing the last line. ; mov al,192 ;lower left corner stosw mov cx,28 ;next 28 characters mov al,196 rep stosw mov al,217 ;lower right corner stosw ret open_window endp ; ;----------------------------------------------------------------------------- ;SCROLL_UP scrolls the window contents up one line. ;----------------------------------------------------------------------------- scroll_up proc near cmp start_value,224 ;can we scroll more? je scrup1 ;no, then do nothing mov ah,6 ;use INT 10h to scroll up mov al,1 ;one line call define_window ;set CX and DX for scroll mov bh,text_attr ;define attribute int 10h ;scroll up inc start_value ;adjust starting value mov al,start_value ;calculate new value to write add al,15 mov dh,window_row ;determine row to be written to add dh,17 mov dl,window_column ;set starting column add dl,2 call write_line ;write the first half of new line add al,16 ;adjust AL add dl,5 ;move cursor to next half of line call write_line ;write second half scrup1: ret scroll_up endp ; ;----------------------------------------------------------------------------- ;SCROLL_DOWN scrolls the window contents down one line. ;----------------------------------------------------------------------------- scroll_down proc near cmp start_value,0 ;can we scroll more? je scrdn1 ;no, then do nothing mov ah,7 ;use INT 10h to scroll down mov al,1 ;one line call define_window ;set CX and DX mov bh,text_attr ;set attribute int 10h ;do the scroll dec start_value ;adjust starting value mov al,start_value ;new value to write mov dh,window_row ;determine row for write add dh,2 mov dl,window_column ;set starting column add dl,2 call write_line ;write new line at top add al,16 ;adjust AL add dl,5 ;move cursor to second half call write_line ;write second half of line scrdn1: ret scroll_down endp ; ;----------------------------------------------------------------------------- ;LAST_WINDOW_PAGE pages the window back one page. ;----------------------------------------------------------------------------- last_window_page proc near cmp start_value,0 ;can we go back more? je last3 ;no, then do nothing cmp start_value,31 ;starting value > 31? ja last1 ;yes, then jump mov start_value,0 ;no, then zero value jmp last2 ;skip next line last1: sub start_value,32 ;adjust START_VALUE last2: call clear_window ;clear interior of window call fill_window ;write the new table last3: ret last_window_page endp ; ;----------------------------------------------------------------------------- ;NEXT_WINDOW_PAGE pages the window forward one page. ;----------------------------------------------------------------------------- next_window_page proc near cmp start_value,224 ;can we go forward more? je next3 ;no, then do nothing cmp start_value,193 ;starting value <193? jb next1 ;yes, then jump mov start_value,224 ;set START_VALUE to maximum jmp next2 ;skip next line next1: add start_value,32 ;adjust for next page next2: call clear_window ;clear window call fill_window ;write new text page next3: ret next_window_page endp ; ;----------------------------------------------------------------------------- ;FIRST_WINDOW_PAGE flips the window contents to the first page. ;----------------------------------------------------------------------------- first_window_page proc near cmp start_value,0 ;already at beginning? je first1 ;yes, then do nothing mov start_value,0 ;zero starting value call clear_window ;clear window call fill_window ;write text to window first1: ret first_window_page endp ; ;----------------------------------------------------------------------------- ;END_WINDOW_PAGE flips the window contents to the final page. ;----------------------------------------------------------------------------- end_window_page proc near cmp start_value,224 ;already at end? je end1 ;yes, then do nothing mov start_value,224 ;set START_VALUE to maximum call clear_window ;clear window call fill_window ;write window text end1: ret end_window_page endp ; ;----------------------------------------------------------------------------- ;CLEAR_WINDOW clears the interior of the window. ;----------------------------------------------------------------------------- clear_window proc near mov ah,6 ;use INT 10h to clear window mov al,0 ;code for blank function call define_window ;set CX and DX mov bh,text_attr ;set attribute for cleared area int 10h ;perform the clear ret clear_window endp ; ;----------------------------------------------------------------------------- ;DEFINE_WINDOW sets the values of CX and DX for call to BIOS scroll functions. ;----------------------------------------------------------------------------- define_window proc near mov ch,window_row ;define upper left corner in CX add ch,2 mov cl,window_column add cl,2 mov dx,cx ;define lower right corner in DX add dh,15 add dl,25 ret define_window endp ; ;----------------------------------------------------------------------------- ;INITIALIZE performs a variety of tasks to set the stage for the resident part ;of the program. ;----------------------------------------------------------------------------- initialize proc near ; ;See if the display adapter is an EGA by looking for the EGA BIOS signature. ; mov ax,0C000h ;set ES to EGA BIOS segment mov es,ax mov di,1Eh ;point DI to signature location lea si,ibm_signature ;point SI to 'IBM' text mov cx,3 ;three bytes to compare cld ;clear DF repe cmpsb ;check three bytes je init1 ;jump if EGA signature found ; ;The display adapter is not an EGA. Determine whether it's a CGA or an MDA. ; mov adapter,0 ;zero ADAPTER for CGA mov ah,15 ;get video mode int 10h cmp al,7 ;is it mode 7? jne init1 ;no, then it's a CGA - jump inc adapter ;yes, it's an MDA - set ADAPTER ; ;If this is a monochrome system, modify color-dependent values accordingly. ; init1: cmp al,7 ;is current video mode 7? je init2 ;yes, then branch cmp al,15 ;is current video mode 15? jne init3 ;no, then skip modification code init2: sub video_segment,800h ;set VIDEO_SEGMENT for monochrome mov border_attr,70h ;change attributes for monochrome mov text_attr,07h mov header_attr,07h ; ;Reset the cursor to scan lines 6 and 7 (color) or 12 and 13 (monochrome). ; init3: mov cx,0C0Dh ;monochrome cursor type cmp al,7 ;video mode 7? je init4 ;yes, then jump cmp al,15 ;video mode 15? je init4 ;yes, then jump mov cx,0607h ;scan lines 6 and 7 for color init4: mov ah,1 ;set cursor type int 10h ; ;Now save the old interrupt 9 vector and replace it with one pointing to the ;code that we will leave behind in memory. ; mov ah,35h ;get current interrupt 9 vector mov al,9 int 21h mov old_keyboard_int,bx ;save vector offset mov old_keyboard_int[2],es ;save vector segment mov ah,25h ;set new vector mov al,9 lea dx,ascview ;point it to body of program int 21h ; ;Exit thru INT 27h and reserve enough room beyond the actual code to store the ;contents of the area of screen that underlies the pop-up window. ; mov dx,offset initialize+1140 ;reserve space for code and buffer int 27h ;terminate-but-stay-resident initialize endp ; code ends end begin