comment % release version 0.2.6 05/02/00 See history.txt for revision notes and differences. floppy diskette boot emulator (aka flopper) jeff leyda jeff@silent.net flat real mode memory routines written by NiX / MASSiVE cpu id code comes from the book "undocumented PC" chooser portion written by demonlord the following code and concept are to remain in the public domain as freeware to be used and modified by anyone who choses to use it. please don't be a dick and steal the code and try to sell it! compiled with TASM 3.0, linked with MS-LINK 5.10 will compile with TLINK using the /3 option. will also compile with MASM/LINK main documentation for program usage can be found in the file INSTALL.HTM or INSTALL.TXT 様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 memory map: 0:0 -> 512k DOS/game 513k -> ? flopper suport routines 1mb -> 1mb+512k DOS/game (1mb defined in equates.inc) 1mb+512k - >1mb+513k registers/reserved space 1mb+513k - >xxx disk image 様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 TODO: .cpu slowdown support keep slowing down and testing the cpu speed til it hits ~5Mhz. All of these games were originally written for a 4.77Mhz machine in the first place. .support for 128 and 1k and 2k byte sector sizes .better keyboard intercept routines. some games don't like the intercept that i'm doing right now. (jumpman) .add opening screen display? .shell to dos feature from within chooser .command line switches to over-ride defaults. ie: disk size, cpu slowdown, etc. .windows version using V-86 mode. We could do SOOO much with this. % STAPEL SEGMENT STACK USE16 'Stack' dw 200 dup(?) STAPEL ENDS CODE SEGMENT USE16 Assume cs:code, ss:stapel ;陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳 ; Include files ;陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳 include constant.inc ; Stuff that never changes. include equates.inc ; run time and compile time variables include debug.inc ; debugger support. Not really needed for now. include flatmem.inc ; Generic Memory and Flat Real Mode routines include revector.inc ; interrupt vector table loading routines include cpu.inc ; detect CPU code support include diskette.inc ; diskette definitions and code include fileio.inc ; file opening, closing, etc code include cmdline.inc ; command line input routines include flopisr.inc ; flopper ISR support code include scrnshot.inc ; screenshot support code include rtc.inc ; real time clock/cpu slowdown routines ;include misc.inc ;junk. old code that may be needed someday ;様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 ; MAIN CODE STARTING POINT ;様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 Start: ; system checks, get into flat memory model call check_cpu ; requires at least a 386. call check_himem ; no himem.sys! call check_2mb ; requires at least 2mb call Set4Gig ; Swap to Flat Real Mode call EnableA20 ; Enable the A20-line cli mov bx, ss mov cs:[ss_val], bx sti ; put chooser at INT 3F push es push cs pop es mov bx, offset chooser mov al, 03fh call changeISR pop es ; check files, load image call process_cmdline ; grab filenames, switches, etc call open_file ; open file if exists jnc open_ok jmp exit open_ok: call get_disk_params ; return disk image Spt/H/T info call load_image ; load diskette image call close_file ; close reboot: call put512high ; copy DOS area high in memory ; prepare for boot call change_base_size ; set BDA memory size to 512k call copy_code ; load flopper support above 512k nop call reset_vectors ; load virgin vector table ; call relocateIrqs ; relocate IRQ 0-7 -->50-57h ; figure out starting location of new INT service ; move this to a subroutine too. mov si, offset flopper_top ; point to start of flopper routines mov bx, offset int13 ; point to start of new INT13 sub bx, si ; from offset of flopper_top mov dx, offset realInt13 ; point to storage for old INT13 inc dx ; add 1 for "db EA" instruction. sub dx, si mov al, 13h call changeISR mov si, offset flopper_top ; point to start of flopper routines mov bx, offset int15 ; point to start of new INT15 sub bx, si ; from offset of flopper_top mov dx, offset realInt15 ; point to storage for old INT15 inc dx ; inc dx sub dx, si mov al, 15h call changeISR mov si, offset flopper_top ; point to start of flopper routines mov bx, offset int5 ; point to start of new INT5 sub bx, si ; from offset of flopper_top mov dx, offset realInt5 ; point to storage for old INT5 inc dx ; add 1 for "db EA" instruction. sub dx, si mov al, 5 call changeISR call disable_cache ; turn off L1 Cache if 486+ ; mov si, offset flopper_top ; mov bx, offset int70 ; sub bx, si ; mov al, 70h ; call changeISR ; call slowdown_cpu ; throttle back to 4.77MHz ; can't start this until INT 70 ; vector is in place cuz Int70 will ; start immediately after this call. ; "load" disk! xor ax, ax mov es, ax ; load 1st sector to 0:7c00 mov bx, 7c00h mov ah, 2 ; read mov al, 1 ; 1 sector mov ch, 0 ; track 0 mov cl, 1 ; sector 1 mov dh, 0 ; head 0 mov dl, 0 ; drive 0 (a:) int 13h xor ax, ax mov bp, ax ; set up registers like they would mov ds, ax ; be for "booting" mov ss, ax mov sp, 400h push 0 ; jump to 0:7c00 to "boot" diskette push 7c00h retf ;様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 ; CHOOSER STARTING POINT ;様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様様 chooser_msg db "Welcome to chooser!",CR,LF db "Current Image is:$" chooser_msg2 db CR,LF,CR,LF,"Select:",CR,LF db " 1. load image",CR,LF db " 2. save image",CR,LF db " 3. Write $" chooser_msg3 db " disk",CR,LF db " 4. Boot current image",CR,LF db " 5. Return to image",CR,LF db "ESC Exit to DOS$" prot_msg db "protect$" enab_msg db "enable$" ss_val dw 0 ; storage for Stack segment ss_ret dw 0 flags db 0 fname db 76 dup(0) newfilestr db CR,LF,CR,LF,'Enter new image filename: $' warning_msg db CR,LF,"Warning! Disk image was written!",CR,LF db "Changes will be lost! Press ESC again to exit$" cga_reg dw ? ; storage for 3d8, 3d9 register mode_page dw ? ; storage for video mode and page chooser: cli mov cs:[ss_ret], ss ; save game SS mov ss, cs:[ss_val] ; restore flopper SS sti pusha push ds push es push cs push cs pop ds pop es ; signal end of interrupt push ax mov al, 20h out 20h, al out 0a0h, al out 20h, al pop ax int 9 ; mov cs:[flags], al ; save flopper flags mov cs:[mode_page], bx ; save video info test al, SCREENSHOT jz chooser_menu call do_screenshot jmp exit_chooser chooser_menu: call savescreen mov dx, CGA_CONTROL_REGISTER in ax, dx mov [cga_reg], ax getselect: mov bx, 0 mov ax, 3 int 10h lea dx, chooser_msg mov ah, 9 int 21h ;print current image filename lea di, fname mov ax, 1212h int 2Fh add di, cx mov byte ptr [di],"$" lea dx, fname mov ah, 9 int 21h mov byte ptr [di],0 ; restore name to asciiz lea dx, chooser_msg2 int 21h test byte ptr flags, DISK_PROTECTED jz wpenabled lea dx, enab_msg int 21h jmp msg3 wpenabled: lea dx, prot_msg int 21h msg3: lea dx, chooser_msg3 int 21h mov ax, word ptr gs:[41ch] ; clear keyboard buffer mov word ptr gs:[41ah],ax xor ax, ax int 16h cmp al, ESCAPE jz check_written cmp al, "1" ; load new image jz load_disk cmp al, "2" ; save current image to HDD jz save_disk cmp al, "3" ; write protect current image jz wp_toggle cmp al, "4" ; reboot current image jz reboot cmp al, "5" ; nothing. jz restoreandexit cmp al, CR jz restoreandexit jmp getselect save_disk: lea dx, fname call save_image and flags, NOT DISK_WRITTEN ; update image written flag jmp getselect wp_toggle: xor flags, DISK_PROTECTED jmp getselect check_written: test flags, DISK_WRITTEN jz exit mov ah, 9 lea dx, warning_msg int 21h xor ax, ax int 16h cmp al,ESCAPE jnz getselect jmp exit load_disk: mov ah, 9 lea dx, newfilestr int 21h lea di, fname ;Filename buffer newkey: xor ax,ax int 16h cmp al,ESCAPE jz Exit cmp al,13 ;Enter jz NewFile cmp al,8 ;Backspace je Erase cmp al,32 ;Space+ jb newkey cmp di,offset FName+75 ;Not too long?? ja newkey stosb ;Store character mov ah,0eh mov bx,7 int 10h ;Show character entered jmp newkey Erase: cmp di,Offset FName jbe NewKey ;Check length mov ah,3 mov bh,0 int 10h ;Get cursor pos dec dl push dx mov ah,2 int 10h ;Move one step left mov ax,0e20h mov bx,7 int 10h ;Erase current char pop dx mov ah,2 int 10h ;Restore cursor pos dec di ;Remove last char from buffer jmp NewKey NewFile: cmp di,Offset FName jbe Exit_chooser ; Nothing entered mov al, 0 ; null terminate stosb lea dx, fname call open_file ; open file if exists jc exit call get_disk_params ; return disk image Spt/H/T info call load_image ; load diskette image call close_file ; close or flags,DISK_CHANGE ; set diskchange flag jmp getselect restoreandexit: mov ax, mode_page xor ah, ah int 10h mov ax, mode_page xchg al, ah mov ah, 05 int 10h call restorescreen ; restore video data mov dx, CGA_CONTROL_REGISTER mov ax, [cga_reg] out dx, ax exit_chooser: ; signal end of interrupt again? push ax mov al, 20h out 20h, al out 0a0h, al out 20h, al pop ax int 9 pop es pop ds popa cli mov ss, cs:[ss_ret] sti mov al, cs:[flags] iret exit: call restore_cache ; re-enable L1 cache if need be call rtc_off ; signal end of interrupt push ax mov al, 20h out 20h, al out 0a0h, al out 20h, al pop ax mov ah, 4ch int 21h endflag: CODE ENDS End Start