page 64,132 Comment @ This is a patch to the ROM BIOS keyboard routine. When the patch is loaded, the Alt, Ctrl, Left Shift and Right Shift keys toggle between their shifted and unshifted states. There are two main entry points. 1. 'Keyloc' sets up the keyboard interupt vector to point to the patch instead of the normal BIOS routine. After Keyloc executes, it leaves the new interupt handler resident in memory. 2. 'Ikeyloc' is the new keyboard interupt handler. The first section is a duplication of the ROM BIOS routine until a point where tests for the input of a Alt, Ctrl, Left Shift or Right Shift key can be made. If it is one of those keys, the appropriate bits in the keyboard flag byte are twiddled. John Black 5225 Pooks Hill Rd. #1715 N. Bethesda MD. 20814 @ port_b equ 60h ; 8255 port a addr timer equ 40h kb_data equ 60h ; keyboard scan code port kb_ctl equ 61h ; control bits for keyboard sense data abso segment at 0 org 24h kb_vector label dword abso ends rom_version = 3 if (rom_version eq 1) or (rom_version eq 2) bioscode segment at 0F000h ; ; Location definitions from Technical Reference Manual for Versions ; 04/24/81 or 10/19/81 of BIOS rom. ; org 0E9AFh ; page A-27 of Technical Reference K16 label far ; resume code if not shift org 0EA23h ; page A-27 K23 label far ; break for shift key org 0EA5Eh ; page A-27 K26 label far ; return from interupt org 0EC24h ; page A-31 K62 label far ; error bioscode ends endif if rom_version eq 3 bioscode segment at 0F000h ; ; Location definitions from Technical Reference Manual for Version ; 10/27/82 of BIOS rom ; org 0E9ADh ; page A-30 of Technical Reference K16 label far ; resume code if not shift org 0EA1Eh ; page A-30 K23 label far ; break for shift key org 0EA59h ; page A-31 K26 label far ; return from interupt org 0EC27h ; page A-35 K62 label far ; error bioscode ends endif biosdata segment at 40h org 17h kb_flag label byte ; ...bit definitions for kb_flag ins_state equ 80h ; insert state is active caps_state equ 40h ; caps lock state has been toggled num_state equ 20h ; num lock state has been toggled scroll_state equ 10h ; scroll lock state has been toggled alt_shift equ 08h ; alternate shift key depressed ctl_shift equ 04h ; control shift key depressed left_shift equ 02h ; left shift key depressed right_shift equ 01h ; right shift key depressed ; ...scan codes num_key equ 69 scroll_key equ 70 alt_key equ 56 ctl_key equ 29 caps_key equ 58 left_key equ 42 right_key equ 54 ins_key equ 82 del_key equ 83 biosdata ends keylocs segment para public 'CODE' assume cs:keylocs keyloc_ident db 'KEYLOC' ident_length equ 6 ikeyloc proc far ; interupt entry point sti ; begin copy of ROM BIOS push ax push bx push cx push dx push si push di push ds push es cld mov ax,biosdata mov ds,ax in al,kb_data push ax in al,kb_ctl mov ah,al or al,80h out kb_ctl,al xchg ah,al out kb_ctl,al pop ax mov ah,al cmp al,0FFh jnz keylocpatch jmp K62 ; End of rom code copy keylocpatch: push ax assume ds:biosdata and al,01111111b ; mask out break indicator cmp al,alt_key je alt_in cmp al,ctl_key je ctrl_in cmp al,left_key je leftshift_in cmp al,right_key je rightshift_in ; ...return to normal bios keyboard routine retbioskey: pop ax jmp K16 alt_in: mov al,alt_shift call Depress_lock ; ... if this is a break, enter bios at K23 pop ax mov ah,alt_shift test al,80h ; if jz fi ; . test kb_flag,alt_shift ; . jnz fi ; . ; / break and not depressed ; . or kb_flag,alt_shift ; . Reset depressed flag jmp K23 ; . Return in case using ; . alt keypad entry fi: ; fi jmp K26 ctrl_in: mov al,ctl_shift call Depress_lock jmp retdone leftshift_in: mov al,left_shift call Depress_lock jmp retdone rightshift_in: mov al,right_shift call Depress_lock jmp retdone retdone: pop ax jmp K26 ikeyloc endp ;--------------------------------------------- ; ; Depress_lock ; ; For keys that normally are depressed and held down ; while another key is depressed. (Cntl for example) ; ; ah input key, with break indicator (80h) ; al contains depressed indicator bit mask ; Down db ? ; indicates the key is held down Depress_lock proc near push dx test ah,80h ; if1 jnz fi1 ; . test Down,al ; . jnz fi1 ; . ; / make and not down test kb_flag,al ; . if2 je else2 ; . . ; . / depressed call high_beep ; . . call delay ; . . call low_beep ; . . mov dl,al ; . . dl:=depressed bit not dl ; . . and kb_flag,dl ; . . key := not depressed jmp fi1 ; . . else2: ; . / not depressed call low_beep ; . . call delay ; . . call high_beep ; . . or kb_flag,al ; . . key := depressed fi1: ; fi1 fi2 test ah,80h ; if5 jnz else5 ; . ; / make or Down,al ; . down := true jmp fi5 ; . else5: ; / break mov dl,al ; . not dl ; . and Down,dl ; . down := false fi5: ; fi5 pop dx ret Depress_lock endp ;--------------------------------- h_cycles equ 20 h_half equ 300 l_cycles equ h_cycles / 3 l_half equ h_half * 3 low_beep proc push dx push bx mov bx,l_cycles mov dx,l_half call beep pop bx pop dx ret low_beep endp high_beep proc push dx push bx mov bx,h_cycles mov dx,h_half call beep pop bx pop dx ret high_beep endp ;--------------------------------- ; Adapted from BIOS Beep routine ; ; bx = # of cycles ; dx = length of half cycle beep proc near push ax push cx in al,kb_ctl push ax k65: and al,0FCh out kb_ctl,al mov cx,dx k66: loop k66 or al,2 out kb_ctl,al mov cx,dx k67: loop k67 dec bx jnz k65 pop ax out kb_ctl,al pop cx pop ax ret beep endp ;-------------------------------- delay proc near push cx mov cx,15000 loop $ pop cx ret delay endp ikeylast equ $ ; last location + 1 to remain in memory stacks segment stack 'STACK' db 64 dup('stack ') stacks ends ;------------------------------------- loaded_mess db 'KEYLOC loaded$' err_mess db 'error - KEYLOC is already loaded$' keyloc proc far push ds sub ax,ax push ax push ds ; save program seg ; ...Check to see if a copy of KEYLOC has ; already been loaded by comparing Keyloc_ident ; with the same locations relative the the current ; keyboard interupt routine ( it is pointed to by the ; the keyboard interupt vector) cld ; increment assume ds:abso mov ax,abso mov ds,ax mov si,offset keyloc_ident mov ax,kb_vector+2 ; segment mov di,kb_vector ; offset to ident sub di,ident_length mov es,ax assume ds:keylocs mov ax,keylocs mov ds,ax mov cx,ident_length repne cmpsb ; ds:[si],es:[di] cmp cx,0 ; if je NotLoaded ; . ; / already loaded mov ah,9h ; . print string mov dx,offset err_mess ; . int 21h ; . pop ds ; . get rid of pseg ret ; . return to DOS NotLoaded: ; fi ; ...set up keyboard interupt vector mov ah,9h mov dx,offset loaded_mess int 21h assume ds:abso mov ax,abso mov ds,ax mov ax,offset ikeyloc ; ip mov kb_vector,ax mov ax,seg ikeyloc ; cs mov kb_vector+2,ax ; ...return to DOS, but leave ikeyloc resident pop es ; get program segment mov es:byte ptr 1,27h ; change int 20 to 27 mov dx,offset ikeylast+100h ; dx:=lastaddr+1+prfx ret keyloc endp keylocs ends end keyloc