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Index > OS Construction > int13h floppy and drive emulation.

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edfed



Joined: 20 Feb 2006
Posts: 4240
Location: 2018
edfed
last night, i coded an emulation of floppy and hard disk using DOS files.

it works for floppy at c:/fd0.bin, i have tested it on 2 of my old applications that used the floppy, it works fine, pretty usefull to replace the old dead floppy drives i have.

basical useage:
Code:
     org 100h ; and maybe any dos compatible header
     call int13h.new
;
; ...your code here
;
     call int13h.old
;
; ... exit program
;
include '/floppyemul/int13h.inc'   
    



it is in order to debug int13h useage without accessing to real hardware.
my floppy drives are dead, then, it can be interesting to play with an image file, and that will be faster than a real floppy, of course.

there can be other bugs but i didn't detect any fo the moment.


all that this "virtual driver" can do is bring a dos file as a drive image in place of a bios disk image, by installing over the original int13h, it will test for a drive number, then, if it is not the virtual drive number (drive 0 in this code) it will call the normal int13h handler.
if it is the virtual drive, it will read, write and get drive parameters from a file.

the file is fd0.inc, and should be located in c:/

the ideal would be first to be able to create this file from the driver if it don't exist.

about hdd emulation, i don't have positive results, it simply ignore the drive id step...
then for hd drives it don't works.


Description: the readme, in a separate file for the moment
Download
Filename: readme.txt
Filesize: 644 Bytes
Downloaded: 92 Time(s)

Description: the software here is given as is, use it at your own risk, etc etc...
Download
Filename: floppyemul.zip
Filesize: 3.03 KB
Downloaded: 72 Time(s)

Post 18 Nov 2010, 16:57
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edfed



Joined: 20 Feb 2006
Posts: 4240
Location: 2018
edfed
lba32 adress test opus1

this is the ram representation of a folder
a succesion of dwords and bytes.
Code:
;supposed to be at LBA= no matter, we are in a fptr,
;in local ram, LBA32 bit offsets maxi.
;and on ram, supposed to be at fptr[seg:0]
;all adresses will be for file link in the 32 bit limit.
;then, it will lead to problems.
macro list [element] {
 common
  local .a
        dd .a-$-4
 forward
        dd element
 common
  .a:
}
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
macro string [arg]  {
 common
  forward
        db arg
 common
        align 4
}
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
f:
.folder='dir'
.file='fil'

org 0

rootdir:
        .size=.end-$
        dd f.folder,.size,.content,.name
.name:  string 'root',0

.content:
        list .fil00,.fil01,.fil02,.fil03,.fil04,.fil05,.fil06,.fil07,.fil08,.fil09

.fil00: dd f.folder,asmdir.size,asmdir/256,@f
@@:     string 'asm',0     ;name

.fil01: dd f.folder,0,0,@f
@@:     string 'images',0

.fil02: dd f.folder,0,0,@f
@@:     string 'sons',0

.fil03: dd f.folder,0,0,@f
@@:     string 'musiques',0

.fil04: dd f.folder,0,0,@f
@@:     string 'films',0

.fil05: dd f.file,0,0,@f
@@:     string 'internet',0

.fil06: dd f.folder,0,0,@f
@@:     string 'datas',0

.fil07: dd f.folder,0,0,@f
@@:     string 'system',0

.fil08: dd f.file,80*2*18*512,floppydrive/256,@f
@@:     string 'fd0.bin',0

.fil09: dd f.file,0,0,@f
@@:     string 'hd0.bin',0

.end:
        align 256

asmdir:
        .size=.end-$
        dd f.folder,.size,.content,.name
.name:  string 'asm',0

.content:
        list .fil00,.fil01,.fil02

.fil00: dd f.folder,0,0,@f
@@:     string 'codes',0

.fil01: dd f.folder,0,0,@f
@@:     string 'fasm',0

.fil02: dd f.folder,0,0,@f
@@:     string 'livres',0

.end:

        align 256
floppydrive:
file 'boot/boot.bin'
file 'shell.com'
    


something like this as a first test of file system management.

the problem will be the file meta datas.
size, location, etc...

where to put them?
in the folder?
in the fileas a gap to a hard disk zone?
Post 19 Nov 2010, 23:13
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