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pascal@24476
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1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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2 ;; ;;
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pascal@24476
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3 ;; "BootProg" Loader v 1.5 by Alexey Frunze (c) 2000-2015 ;;
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pascal@24476
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4 ;; 2-clause BSD license. ;;
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pascal@24476
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5 ;; ;;
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pascal@24476
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6 ;; ;;
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pascal@24476
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7 ;; How to Compile: ;;
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pascal@24476
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8 ;; ~~~~~~~~~~~~~~~ ;;
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pascal@24476
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9 ;; nasm boot32.asm -f bin -o boot32.bin ;;
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pascal@24476
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10 ;; ;;
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pascal@24476
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11 ;; ;;
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pascal@24476
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12 ;; Features: ;;
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pascal@24476
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13 ;; ~~~~~~~~~ ;;
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pascal@24535
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14 ;; - FAT32 supported using BIOS int 13h function 42h (IOW, it will only ;;
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pascal@24535
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15 ;; work with modern BIOSes supporting HDDs bigger than 8 GB) ;;
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pascal@24476
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16 ;; ;;
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pascal@24476
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17 ;; - Loads a 16-bit executable file in the MS-DOS .COM or .EXE format ;;
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pascal@24476
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18 ;; from the root directory of a disk and transfers control to it ;;
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pascal@24476
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19 ;; (the "ProgramName" variable holds the name of the file to be loaded) ;;
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pascal@25460
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20 ;; Its maximum size can be up to 637KB without Extended BIOS Data area. ;;
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pascal@24476
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21 ;; ;;
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pascal@24476
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22 ;; - Prints an error if the file isn't found or couldn't be read ;;
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pascal@24476
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23 ;; ("File not found" or "Read error") ;;
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pascal@24476
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24 ;; and waits for a key to be pressed, then executes the Int 19h ;;
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pascal@24476
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25 ;; instruction and lets the BIOS continue bootstrap. ;;
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pascal@24476
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26 ;; ;;
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pascal@24476
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27 ;; ;;
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pascal@25564
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28 ;; Known Limitation: ;;
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pascal@25564
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29 ;; ~~~~~~~~~~~~~~~~~ ;;
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pascal@25564
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30 ;; - Need a up to date field bpbHiddenSectors to work in a partition ; ;;
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pascal@25564
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31 ;; most formatters don't update it correcly in extended partitions. ;;
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pascal@25564
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32 ;; ;;
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pascal@25564
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33 ;; - Requires i80386 or better CPU. ;;
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pascal@25564
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34 ;; ;;
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pascal@25564
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35 ;; ;;
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pascal@24476
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36 ;; Known Bugs: ;;
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pascal@24476
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37 ;; ~~~~~~~~~~~ ;;
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pascal@24476
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38 ;; - All bugs are fixed as far as I know. The boot sector has been tested ;;
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pascal@24476
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39 ;; on my HDD and an 8GB USB stick. ;;
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pascal@24476
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40 ;; ;;
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pascal@24476
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41 ;; ;;
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pascal@24476
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42 ;; Memory Layout: ;;
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pascal@24476
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43 ;; ~~~~~~~~~~~~~~ ;;
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pascal@24476
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44 ;; The diagram below shows the typical memory layout. The actual location ;;
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pascal@24476
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45 ;; of the boot sector and its stack may be lower than A0000H if the BIOS ;;
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pascal@24476
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46 ;; reserves memory for its Extended BIOS Data Area just below A0000H and ;;
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pascal@24476
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47 ;; reports less than 640 KB of RAM via its Int 12H function. ;;
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pascal@24476
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48 ;; ;;
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pascal@24476
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49 ;; physical address ;;
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pascal@24476
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50 ;; +------------------------+ 00000H ;;
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pascal@24476
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51 ;; | Interrupt Vector Table | ;;
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pascal@24476
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52 ;; +------------------------+ 00400H ;;
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pascal@24476
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53 ;; | BIOS Data Area | ;;
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pascal@24476
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54 ;; +------------------------+ 00500H ;;
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pascal@24476
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55 ;; | PrtScr Status / Unused | ;;
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pascal@24476
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56 ;; +------------------------+ 00600H ;;
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pascal@24476
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57 ;; | Loaded Image | ;;
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pascal@24476
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58 ;; +------------------------+ nnnnnH ;;
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pascal@24476
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59 ;; | Available Memory | ;;
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pascal@25460
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60 ;; +------------------------+ A0000H - 1KB ;;
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pascal@24476
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61 ;; | Boot Sector | ;;
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pascal@25460
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62 ;; +------------------------+ A0000H - 0.5KB ;;
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pascal@25460
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63 ;; | 0.5KB Boot Stack | ;;
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pascal@24476
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64 ;; +------------------------+ A0000H ;;
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pascal@24476
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65 ;; | Video RAM | ;;
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pascal@24476
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66 ;; ;;
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pascal@24476
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67 ;; ;;
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pascal@24476
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68 ;; Boot Image Startup (register values): ;;
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pascal@24476
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69 ;; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ;;
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pascal@24945
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70 ;; ax = 0ffffh (both FCB in the PSP don't have a valid drive identifier), ;;
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pascal@25454
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71 ;; bx = 0, dl = BIOS boot drive number (e.g. 0, 80H) ;;
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pascal@24476
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72 ;; cs:ip = program entry point ;;
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pascal@24476
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73 ;; ss:sp = program stack (don't confuse with boot sector's stack) ;;
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pascal@24476
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74 ;; COM program defaults: cs = ds = es = ss = 50h, sp = 0, ip = 100h ;;
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pascal@24476
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75 ;; EXE program defaults: ds = es = EXE data - 10h (fake MS-DOS psp), ;;
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pascal@24476
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76 ;; cs:ip and ss:sp depends on EXE header ;;
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pascal@24476
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77 ;; Magic numbers: ;;
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pascal@24476
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78 ;; si = 16381 (prime number 2**14-3) ;;
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pascal@24476
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79 ;; di = 32749 (prime number 2**15-19) ;;
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pascal@24476
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80 ;; bp = 65521 (prime number 2**16-15) ;;
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pascal@24476
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81 ;; The magic numbers let the program know whether it has been loaded by ;;
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pascal@24476
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82 ;; this boot sector or by MS-DOS, which may be handy for universal, bare- ;;
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pascal@24476
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83 ;; metal and MS-DOS programs. ;;
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pascal@24945
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84 ;; The command line contains no arguments. ;;
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pascal@24476
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85 ;; ;;
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pascal@24476
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86 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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87
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pascal@24491
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88 %define bx(label) bx+label-boot
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pascal@25449
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89 %define si(label) si+label-boot
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pascal@25485
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90 ExtraBootSector equ 1
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pascal@25449
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91 ClusterMask equ 1 ; +9 bytes
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pascal@25460
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92 NullEntryCheck equ 1 ; +5 bytes
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pascal@25572
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93 CheckAttrib equ 0 ; +6 bytes
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pascal@25569
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94 NonMirroredFATs equ 1 ; +20 bytes
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pascal@25569
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95 ReadRetry equ 1 ; +6/7 bytes
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pascal@25569
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96 LBA48bits equ 1 ; +10 bytes
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pascal@25569
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97 CHSsupport equ 1 ; +35 bytes max 8GB
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pascal@25569
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98 CHSgeometryCheck equ 1 ; +20 bytes
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pascal@25569
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99 CHSsanityCheck equ 1 ; +9 bytes
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pascal@25569
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100 SectorOf512Bytes equ 0 ; -4 bytes
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pascal@25458
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101 Always2FATs equ 0 ; -4 bytes
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pascal@25564
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102 WaitForKey equ 0 ; +5 bytes
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pascal@24491
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103
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pascal@24476
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104 [BITS 16]
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pascal@25564
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105 [CPU 386]
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pascal@24476
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106
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pascal@24478
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107 ImageLoadSeg equ 60h ; <=07Fh because of "push byte ImageLoadSeg" instructions
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pascal@25460
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108 StackSize equ 512
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pascal@24476
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109
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pascal@24476
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110 [SECTION .text]
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pascal@24476
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111 [ORG 0]
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pascal@24476
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112
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pascal@24476
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113 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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114 ;; Boot sector starts here ;;
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pascal@24476
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115 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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116
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pascal@24491
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117 boot:
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pascal@25458
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118 DriveNumber equ boot+0
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pascal@25458
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119 HiLBA equ boot+2
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pascal@24476
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120 jmp short start ; MS-DOS/Windows checks for this jump
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pascal@24476
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121 nop
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pascal@24476
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122 bsOemName DB "BootProg" ; 0x03
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pascal@24476
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123
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pascal@24476
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124 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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125 ;; BPB1 starts here ;;
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pascal@24476
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126 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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127
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pascal@25564
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128 bpbBytesPerSector DW 0 ; 0x0B 512, 1024, 2048 or 4096
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pascal@25564
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129 bpbSectorsPerCluster DB 0 ; 0x0D 1, 2, 4, 8, 16, 32, 64 or 128
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pascal@25564
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130 bpbReservedSectors DW 0 ; 0x0E 32
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pascal@25564
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131 bpbNumberOfFATs DB 0 ; 0x10 2
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pascal@25564
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132 bpbRootEntries DW 0 ; 0x11 0
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pascal@25564
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133 bpbTotalSectors DW 0 ; 0x13 0
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pascal@25564
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134 bpbMedia DB 0 ; 0x15 F8, F0
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pascal@25564
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135 bpbSectorsPerFAT DW 0 ; 0x16 0
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pascal@24479
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136 bpbSectorsPerTrack DW 0 ; 0x18
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pascal@24479
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137 bpbHeadsPerCylinder DW 0 ; 0x1A
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pascal@24479
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138 bpbHiddenSectors DD 0 ; 0x1C
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pascal@24479
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139 bpbTotalSectorsBig DD 0 ; 0x20
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pascal@24476
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140
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pascal@24476
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141 ;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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142 ;; BPB1 ends here ;;
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pascal@24476
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143 ;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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144
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pascal@24476
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145 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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146 ;; BPB2 starts here ;;
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pascal@24476
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147 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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148
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pascal@24479
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149 bsSectorsPerFAT32 DD 0 ; 0x24
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pascal@24479
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150 bsExtendedFlags DW 0 ; 0x28
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pascal@24479
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151 bsFSVersion DW 0 ; 0x2A
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pascal@24479
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152 bsRootDirectoryClusterNo DD 0 ; 0x2C
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pascal@24479
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153 bsFSInfoSectorNo DW 0 ; 0x30
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pascal@24479
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154 bsBackupBootSectorNo DW 0 ; 0x32
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pascal@24479
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155 bsreserved times 12 DB 0 ; 0x34
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pascal@24479
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156 bsDriveNumber DB 0 ; 0x40
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pascal@24479
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157 bsreserved1 DB 0 ; 0x41
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pascal@25564
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158 bsExtendedBootSignature DB 0 ; 0x42 29
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pascal@24479
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159 bsVolumeSerialNumber DD 0 ; 0x43
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pascal@25458
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160 bsVolumeLabel times 11 DB " " ; 0x47 "NO NAME "
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pascal@25458
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161 bsFileSystemName times 8 DB " " ; 0x52 "FAT32 "
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pascal@24476
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162
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pascal@24476
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163 ;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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164 ;; BPB2 ends here ;;
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pascal@24476
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165 ;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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166
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pascal@24476
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167 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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168 ;; Boot sector code starts here ;;
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pascal@24476
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169 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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170
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pascal@24476
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171 start:
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pascal@24476
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172 cld
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pascal@24476
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173
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pascal@24476
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174 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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175 ;; How much RAM is there? ;;
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pascal@24476
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176 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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177
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pascal@24476
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178 int 12h ; get conventional memory size (in KBs)
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pascal@25460
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179 dec ax ; reserve 1K bytes for the code and the stack
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pascal@24525
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180 mov cx, 106h
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pascal@24525
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181 shl ax, cl ; and convert it to 16-byte paragraphs
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pascal@24476
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182
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pascal@24476
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183 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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184 ;; Reserve memory for the boot sector and its stack ;;
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pascal@24476
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185 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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186
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pascal@24525
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187 mov es, ax ; cs:0 = ds:0 = ss:0 -> top - 512 - StackSize
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pascal@25485
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188 %if ExtraBootSector == 0
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pascal@24525
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189 mov ss, ax
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pascal@24525
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190 mov sp, 512+StackSize ; bytes 0-511 are reserved for the boot code
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pascal@25485
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191 %endif
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pascal@24476
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192
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pascal@24476
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193 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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194 ;; Copy ourselves to top of memory ;;
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pascal@24476
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195 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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196
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pascal@24476
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197 mov si, 7C00h
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pascal@24476
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198 xor di, di
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pascal@24476
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199 mov ds, di
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pascal@25449
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200 push es
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pascal@25449
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201 mov [si(DriveNumber)], dx ; store BIOS boot drive number
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pascal@24478
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202 rep movsw
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pascal@24476
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203
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pascal@24476
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204 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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205 ;; Jump to the copy ;;
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pascal@24476
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206 ;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
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207
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pascal@25486
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208 %if ExtraBootSector != 0
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pascal@25486
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209 push word main
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pascal@25486
|
210 %else
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pascal@25450
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211 push byte main
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pascal@25486
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212 %endif
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pascal@24476
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213 retf
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pascal@24476
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214
|
pascal@25486
|
215 %if ExtraBootSector != 0
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pascal@25486
|
216 %macro MovedCode 0
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pascal@25486
|
217 %endif
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pascal@24476
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218 main:
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pascal@25485
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219 %if ExtraBootSector != 0
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pascal@25485
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220 add al, 32
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pascal@25564
|
221 push ax
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pascal@25564
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222 %endif
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pascal@25564
|
223 ;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@25564
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224 ;; Get drive parameters ;;
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pascal@25564
|
225 ;; Update heads count ;;
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pascal@25564
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226 ;; for current BIOS ;;
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pascal@25564
|
227 ;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@25564
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228
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pascal@25564
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229 %if CHSgeometryCheck != 0
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pascal@25564
|
230 mov ah, 8 ; update AX,BL,CX,DX,DI, and ES registers
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pascal@25564
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231 int 13h ; may destroy SI,BP, and DS registers
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pascal@25564
|
232 %endif
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pascal@25564
|
233 push cs
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pascal@25564
|
234 pop ds
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pascal@25564
|
235 xor ebx, ebx
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pascal@25564
|
236
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pascal@25564
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237 %if CHSgeometryCheck != 0
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pascal@25564
|
238 and cx, byte 3Fh
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pascal@25564
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239 je BadParams ; verify updated and validity
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pascal@25564
|
240 mov [bx(bpbSectorsPerTrack)], cx
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pascal@25564
|
241 mov cl, dh
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pascal@25564
|
242 inc cx
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pascal@25564
|
243 mov [bx(bpbHeadsPerCylinder)], cx
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pascal@25564
|
244 xor cx, cx
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pascal@25564
|
245 BadParams:
|
pascal@25564
|
246 %endif
|
pascal@25564
|
247 %if ExtraBootSector != 0
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pascal@25564
|
248 pop es
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pascal@25564
|
249 mul ebx ; edx:eax = 0
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pascal@25564
|
250 inc ax
|
pascal@25485
|
251 call ReadSectorBoot
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pascal@25485
|
252 push ds
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pascal@25485
|
253 pop ss
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pascal@25485
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254 mov sp, 512+StackSize ; bytes 0-511 are reserved for the boot code
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pascal@25485
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255 %endif
|
pascal@24476
|
256
|
pascal@25449
|
257 %if ClusterMask != 0
|
pascal@24491
|
258 and byte [bx(bsRootDirectoryClusterNo+3)], 0Fh ; mask cluster value
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pascal@25449
|
259 %endif
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pascal@24491
|
260 mov esi, [bx(bsRootDirectoryClusterNo)] ; esi=cluster # of root dir
|
pascal@24476
|
261
|
pascal@24478
|
262 push byte ImageLoadSeg
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pascal@24478
|
263 pop es
|
pascal@25449
|
264
|
pascal@25449
|
265 RootDirReadContinue:
|
pascal@25458
|
266 call ReadClusterSector ; read one sector of the root dir
|
pascal@24476
|
267
|
pascal@24476
|
268 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
269 ;; Look for the COM/EXE file to load and run ;;
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pascal@24476
|
270 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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pascal@24476
|
271
|
pascal@24476
|
272 xor di, di ; es:di -> root entries array
|
pascal@24476
|
273
|
pascal@24476
|
274 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
275 ;; Looks for a file/dir by its name ;;
|
pascal@24476
|
276 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
277 ;; Input: DS:SI -> file name (11 chars) ;;
|
pascal@24478
|
278 ;; ES:DI -> root directory array ;;
|
pascal@24525
|
279 ;; BP = paragraphs in sector ;;
|
pascal@24476
|
280 ;; Output: ESI = cluster number ;;
|
pascal@24476
|
281 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
282
|
pascal@24476
|
283 FindNameCycle:
|
pascal@25449
|
284 %if NullEntryCheck != 0
|
pascal@24525
|
285 cmp byte [es:di], bh
|
pascal@24478
|
286 je ErrFind ; end of root directory (NULL entry found)
|
pascal@25449
|
287 %endif
|
pascal@24478
|
288 pusha
|
pascal@25454
|
289 mov cl, NameLength
|
pascal@24525
|
290 mov si, ProgramName ; ds:si -> program name
|
pascal@24476
|
291 repe cmpsb
|
pascal@25467
|
292 VolumeLabel equ 8
|
pascal@25467
|
293 SubDirectory equ 10h
|
pascal@25564
|
294 %if CheckAttrib != 0
|
pascal@25467
|
295 jnz SkipFindName
|
pascal@25467
|
296 test byte [es:di], VolumeLabel+SubDirectory
|
pascal@25467
|
297 SkipFindName:
|
pascal@25467
|
298 %endif
|
pascal@24525
|
299 je FindNameFound
|
pascal@24478
|
300 popa
|
pascal@24525
|
301 add di, byte 32
|
pascal@24476
|
302 dec bp
|
pascal@24476
|
303 dec bp
|
pascal@24476
|
304 jnz FindNameCycle ; next root entry
|
pascal@25458
|
305 loop RootDirReadContinue ; next sector in cluster
|
pascal@25458
|
306 cmp esi, 0FFFFFF6h ; carry=0 if last cluster, and carry=1 otherwise
|
pascal@25458
|
307 jnc RootDirReadContinue ; continue to the next root dir cluster
|
pascal@24478
|
308 ErrFind:
|
pascal@24478
|
309 call Error ; end of root directory (dir end reached)
|
pascal@24476
|
310 db "File not found."
|
pascal@25564
|
311 %if ExtraBootSector != 0
|
pascal@25564
|
312 %endm
|
pascal@25564
|
313 %macro BootFileName 0
|
pascal@25564
|
314 %endif
|
pascal@24476
|
315 FindNameFound:
|
pascal@24525
|
316 push word [es:di+14h-11]
|
pascal@24525
|
317 push word [es:di+1Ah-11]
|
pascal@24478
|
318 pop esi ; esi = cluster no. cx = 0
|
pascal@24476
|
319
|
pascal@24525
|
320 dec dword [es:di+1Ch-11] ; load ((n - 1)/256)*16 +1 paragraphs
|
pascal@24525
|
321 imul di, [es:di+1Ch+1-11], byte 16 ; file size in paragraphs (full pages)
|
pascal@24476
|
322
|
pascal@24476
|
323 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
324 ;; Load the entire file ;;
|
pascal@24476
|
325 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
326
|
pascal@24476
|
327 push es
|
pascal@24476
|
328 FileReadContinue:
|
pascal@24476
|
329 push di
|
pascal@25458
|
330 call ReadClusterSector ; read one sector of the boot file
|
pascal@25458
|
331 dec cx
|
pascal@24476
|
332 mov di, es
|
pascal@24478
|
333 add di, bp
|
pascal@24478
|
334 mov es, di ; es:bx updated
|
pascal@24476
|
335 pop di
|
pascal@24478
|
336
|
pascal@24476
|
337 sub di, bp
|
pascal@24476
|
338 jae FileReadContinue
|
pascal@24943
|
339 xor ax, ax
|
pascal@24476
|
340 pop bp
|
pascal@24476
|
341
|
pascal@24476
|
342 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
343 ;; Type detection, .COM or .EXE? ;;
|
pascal@24476
|
344 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
345
|
pascal@24476
|
346 mov ds, bp ; bp=ds=seg the file is loaded to
|
pascal@24535
|
347
|
pascal@24476
|
348 add bp, [bx+08h] ; bp = image base
|
pascal@24476
|
349 mov di, [bx+18h] ; di = reloc table pointer
|
pascal@24476
|
350
|
pascal@24476
|
351 cmp word [bx], 5A4Dh ; "MZ" signature?
|
pascal@24476
|
352 je RelocateEXE ; yes, it's an EXE program
|
pascal@24476
|
353
|
pascal@24476
|
354 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
355 ;; Setup and run a .COM program ;;
|
pascal@24535
|
356 ;; Set CS=DS=ES=SS SP=0 IP=100h ;;
|
pascal@25454
|
357 ;; AX=0ffffh BX=0 DX=drive and ;;
|
pascal@25454
|
358 ;; cmdline=void ;;
|
pascal@24476
|
359 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
360
|
pascal@24535
|
361 mov di, 100h ; ip
|
pascal@24476
|
362 mov bp, ImageLoadSeg-10h ; "org 100h" stuff :)
|
pascal@24476
|
363 mov ss, bp
|
pascal@24476
|
364 xor sp, sp
|
pascal@24476
|
365 push bp ; cs, ds and es
|
pascal@25486
|
366 jmp short Run
|
pascal@25485
|
367 %if ExtraBootSector != 0
|
pascal@25486
|
368 %endm
|
pascal@25564
|
369 %macro BootCode 0
|
pascal@25485
|
370 %endif
|
pascal@24476
|
371
|
pascal@24476
|
372 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
373 ;; Relocate, setup and run a .EXE program ;;
|
pascal@24476
|
374 ;; Set CS:IP, SS:SP, DS, ES and AX according ;;
|
pascal@24476
|
375 ;; to wiki.osdev.org/MZ#Initial_Program_State ;;
|
pascal@25454
|
376 ;; AX=0ffffh BX=0 DX=drive cmdline=void ;;
|
pascal@24476
|
377 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
378
|
pascal@24476
|
379 ReloCycle:
|
pascal@24476
|
380 add [di+2], bp ; item seg (abs)
|
pascal@24476
|
381 les si, [di] ; si = item ofs, es = item seg
|
pascal@24476
|
382 add [es:si], bp ; fixup
|
pascal@24525
|
383 scasw ; di += 2
|
pascal@24525
|
384 scasw ; point to next entry
|
pascal@24476
|
385
|
pascal@24476
|
386 RelocateEXE:
|
pascal@24942
|
387 dec word [bx+06h] ; reloc items, 32768 max (128KB table)
|
pascal@24942
|
388 jns ReloCycle
|
pascal@24942
|
389
|
pascal@24945
|
390 les si, [bx+0Eh]
|
pascal@24945
|
391 add si, bp
|
pascal@24945
|
392 mov ss, si ; ss for EXE
|
pascal@24945
|
393 mov sp, es ; sp for EXE
|
pascal@24476
|
394
|
pascal@24476
|
395 lea si, [bp-10h] ; ds and es both point to the segment
|
pascal@24476
|
396 push si ; containing the PSP structure
|
pascal@24476
|
397
|
pascal@24476
|
398 add bp, [bx+16h] ; cs for EXE
|
pascal@24535
|
399 mov di, [bx+14h] ; ip for EXE
|
pascal@24476
|
400 Run:
|
pascal@24476
|
401 pop ds
|
pascal@24476
|
402 push bp
|
pascal@24535
|
403 push di
|
pascal@24476
|
404 push ds
|
pascal@24476
|
405 pop es
|
pascal@24942
|
406 mov [80h], ax ; clear cmdline
|
pascal@24942
|
407 dec ax ; both FCB in the PSP don't have a valid drive identifier
|
pascal@24476
|
408
|
pascal@24476
|
409 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
410 ;; Set the magic numbers so the program knows that it ;;
|
pascal@24476
|
411 ;; has been loaded by this bootsector and not by MS-DOS ;;
|
pascal@24476
|
412 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
413 mov si, 16381 ; prime number 2**14-3
|
pascal@24476
|
414 mov di, 32749 ; prime number 2**15-19
|
pascal@24476
|
415 mov bp, 65521 ; prime number 2**16-15
|
pascal@24476
|
416
|
pascal@24476
|
417 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
418 ;; All done, transfer control to the program now ;;
|
pascal@24476
|
419 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
420 retf
|
pascal@25485
|
421 %if ExtraBootSector != 0
|
pascal@25485
|
422 %endm
|
pascal@25485
|
423 %endif
|
pascal@24476
|
424
|
pascal@25458
|
425 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
426 ;; Error Messaging Code ;;
|
pascal@25458
|
427 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
428
|
pascal@25458
|
429 Error:
|
pascal@25458
|
430 pop si
|
pascal@25458
|
431 puts:
|
pascal@25458
|
432 mov ah, 0Eh
|
pascal@25458
|
433 mov bl, 7
|
pascal@25458
|
434 lodsb
|
pascal@25458
|
435 int 10h
|
pascal@25458
|
436 cmp al, '.'
|
pascal@25458
|
437 jne puts
|
pascal@25564
|
438 %if WaitForKey != 0
|
pascal@25458
|
439 cbw
|
pascal@25458
|
440 int 16h ; wait for a key...
|
pascal@25458
|
441 int 19h ; bootstrap
|
pascal@25564
|
442 %endif
|
pascal@25458
|
443
|
pascal@25458
|
444 Stop:
|
pascal@25458
|
445 hlt
|
pascal@25458
|
446 jmp short Stop
|
pascal@25458
|
447
|
pascal@25458
|
448 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
449 ;; Reads a FAT32 sector ;;
|
pascal@25458
|
450 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
451 ;; Inout: ES:BX -> buffer ;;
|
pascal@25458
|
452 ;; EAX = prev sector ;;
|
pascal@25458
|
453 ;; CX = rem sectors in cluster ;;
|
pascal@25458
|
454 ;; ESI = next cluster ;;
|
pascal@25458
|
455 ;; Output: EAX = current sector ;;
|
pascal@25458
|
456 ;; CX = rem sectors in cluster ;;
|
pascal@25458
|
457 ;; ESI = next cluster ;;
|
pascal@25458
|
458 ;; BP -> para / sector ;;
|
pascal@25458
|
459 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
460
|
pascal@25458
|
461 ReadClusterSector:
|
pascal@25458
|
462 %if SectorOf512Bytes != 0
|
pascal@25458
|
463 mov bp, 32 ; bp = paragraphs per sector
|
pascal@25458
|
464 %else
|
pascal@24525
|
465 mov bp, [bx(bpbBytesPerSector)]
|
pascal@24525
|
466 shr bp, 4 ; bp = paragraphs per sector
|
pascal@25458
|
467 %endif
|
pascal@25564
|
468 inc eax ; adjust LBA for next sector
|
pascal@24525
|
469 inc cx
|
pascal@24525
|
470 loop ReadSectorLBA
|
pascal@24525
|
471
|
pascal@25449
|
472 mul ebx ; edx:eax = 0
|
pascal@25458
|
473 %if SectorOf512Bytes != 0
|
pascal@25458
|
474 mov al, 128 ; ax=# of FAT32 entries per sector
|
pascal@25458
|
475 %else
|
pascal@24945
|
476 imul ax, bp, byte 4 ; ax=# of FAT32 entries per sector
|
pascal@25458
|
477 %endif
|
pascal@24525
|
478 lea edi, [esi-2] ; esi=cluster #
|
pascal@24476
|
479 xchg eax, esi
|
pascal@24478
|
480 div esi ; eax=FAT sector #, edx=entry # in sector
|
pascal@24476
|
481
|
pascal@24525
|
482 imul si, dx, byte 4 ; si=entry # in sector, clear C
|
pascal@25485
|
483 %if NonMirroredFATs != 0
|
pascal@25564
|
484 cdq
|
pascal@25485
|
485 or dl, byte [bx(bsExtendedFlags)]
|
pascal@25485
|
486 jns MirroredFATs ; Non-mirrored FATs ?
|
pascal@25485
|
487 and dl, 0Fh
|
pascal@25485
|
488 imul edx, dword [bx(bsSectorsPerFAT32)] ; we need to read the active one
|
pascal@25485
|
489 add eax, edx
|
pascal@25485
|
490 MirroredFATs:
|
pascal@25564
|
491 cdq
|
pascal@25485
|
492 %else
|
pascal@25485
|
493 %if LBA48bits != 0
|
pascal@25564
|
494 cdq
|
pascal@25485
|
495 %endif
|
pascal@25449
|
496 %endif
|
pascal@25458
|
497 call ReadSectorLBAfromFAT ; read 1 FAT32 sector
|
pascal@24476
|
498
|
pascal@25449
|
499 %if ClusterMask != 0
|
pascal@24478
|
500 and byte [es:si+3], 0Fh ; mask cluster value
|
pascal@25449
|
501 %endif
|
pascal@24478
|
502 mov esi, [es:si] ; esi=next cluster #
|
pascal@24476
|
503
|
pascal@25458
|
504 %if Always2FATs != 0
|
pascal@25458
|
505 imul eax, dword [bx(bsSectorsPerFAT32)], 2
|
pascal@25458
|
506 %else
|
pascal@24525
|
507 movzx eax, byte [bx(bpbNumberOfFATs)]
|
pascal@24525
|
508 mul dword [bx(bsSectorsPerFAT32)]
|
pascal@25458
|
509 %endif
|
pascal@24525
|
510
|
pascal@24525
|
511 xchg eax, edi
|
pascal@25454
|
512 movzx ecx, byte [bx(bpbSectorsPerCluster)] ; 8..128
|
pascal@24945
|
513 mul ecx ; edx:eax=sector number in data area
|
pascal@24525
|
514 add eax, edi
|
pascal@24476
|
515
|
pascal@25458
|
516 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
517 ;; Reads a sector form the start of FAT ;;
|
pascal@25458
|
518 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
519
|
pascal@25458
|
520 ReadSectorLBAfromFAT:
|
pascal@25449
|
521 %if LBA48bits != 0
|
pascal@25564
|
522 push dx
|
pascal@25449
|
523 %endif
|
pascal@25454
|
524 mov dx, [bx(bpbReservedSectors)]
|
pascal@25564
|
525 add eax, edx
|
pascal@25565
|
526 %if LBA48bits != 0
|
pascal@25564
|
527 pop dx ; 16TB FAT32 max
|
pascal@25564
|
528 adc dx, bx
|
pascal@25564
|
529 ReadSectorBoot:
|
pascal@25564
|
530 mov [bx(HiLBA)], dx
|
pascal@25564
|
531 %endif
|
pascal@24476
|
532
|
pascal@24478
|
533 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
534 ;; Reads a sector using BIOS Int 13h fn 42h ;;
|
pascal@24478
|
535 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25564
|
536 ;; Input: EAX+EDX = LBA ;;
|
pascal@24478
|
537 ;; ES:BX -> buffer address ;;
|
pascal@25564
|
538 ;; Keep: ESI = next cluster ;;
|
pascal@25564
|
539 ;; EDI = data cluster ;;
|
pascal@25564
|
540 ;; BP = paragraphs / sector ;;
|
pascal@25564
|
541 ;; CX = sector count ;;
|
pascal@24478
|
542 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
543
|
pascal@24476
|
544 ReadSectorLBA:
|
pascal@25449
|
545 %if LBA48bits != 0
|
pascal@25564
|
546 mov dx, [bx(HiLBA)]
|
pascal@25564
|
547 %else
|
pascal@25564
|
548 xor dx, dx ; 2TB FAT32 max
|
pascal@25564
|
549 ReadSectorBoot:
|
pascal@25449
|
550 %endif
|
pascal@25564
|
551 pushad
|
pascal@24476
|
552
|
pascal@25564
|
553 add eax, [bx(bpbHiddenSectors)]
|
pascal@25564
|
554 adc dx, bx ; 2TB partition offset max
|
pascal@25564
|
555
|
pascal@25564
|
556 push edx
|
pascal@24478
|
557 push eax
|
pascal@24476
|
558 push es
|
pascal@24476
|
559 push bx
|
pascal@24478
|
560 push byte 1 ; sector count word = 1
|
pascal@24525
|
561 push byte 16 ; packet size byte = 16, reserved byte = 0
|
pascal@24525
|
562
|
pascal@25449
|
563 %if CHSsupport != 0
|
pascal@25449
|
564 ; Busybox mkdosfs creates fat32 for floppies.
|
pascal@25449
|
565 ; Floppies may support CHS only.
|
pascal@25564
|
566 %if LBA48bits != 0
|
pascal@25564
|
567 ; The following check is only useful with bpbSectorsPerTrack < 8 with disk > 4TB...
|
pascal@25564
|
568 ; setnz dl ; force cylinder overflow without divide error
|
pascal@25458
|
569 %endif
|
pascal@25564
|
570 movzx ecx, word [bx(bpbSectorsPerTrack)]
|
pascal@25564
|
571 idiv ecx
|
pascal@25564
|
572 ; eax = LBA / SPT
|
pascal@25564
|
573 ; edx = LBA % SPT = sector - 1
|
pascal@25449
|
574 inc dx
|
pascal@25564
|
575 push dx ; save sector no.
|
pascal@25564
|
576 cdq
|
pascal@25564
|
577 mov cx, word [bx(bpbHeadsPerCylinder)]
|
pascal@25564
|
578 idiv ecx
|
pascal@25564
|
579 pop cx
|
pascal@25564
|
580 ; eax = (LBA / SPT) / HPC = cylinder
|
pascal@25564
|
581 ; dl = (LBA / SPT) % HPC = head
|
pascal@25449
|
582
|
pascal@25458
|
583 xchg ch, al ; clear al
|
pascal@25449
|
584 ; ch = LSB 0...7 of cylinder no.
|
pascal@25564
|
585 %if CHSsanityCheck != 0
|
pascal@25564
|
586 shl eax, 6
|
pascal@25564
|
587 %else
|
pascal@25564
|
588 shl ax, 6
|
pascal@25564
|
589 %endif
|
pascal@25564
|
590 or cl, ah
|
pascal@25449
|
591 ; cl = MSB 8...9 of cylinder no. + sector no.
|
pascal@25449
|
592 mov dh, dl
|
pascal@25449
|
593 ; dh = head no.
|
pascal@25449
|
594 %endif
|
pascal@25449
|
595
|
pascal@25454
|
596 ReadSectorRetry:
|
pascal@25564
|
597 mov dl, [bx(DriveNumber)] ; restore BIOS boot drive number
|
pascal@24525
|
598 mov si, sp
|
pascal@24478
|
599 mov ah, 42h ; ah = 42h = extended read function no.
|
pascal@24478
|
600 int 13h ; extended read sectors (DL, DS:SI)
|
pascal@24478
|
601 jnc ReadSuccess ; CF = 0 if no error
|
pascal@24476
|
602
|
pascal@25449
|
603 %if CHSsupport != 0
|
pascal@25572
|
604 mov ax, 201h ; al = sector count = 1
|
pascal@25572
|
605 ; ah = 2 = read function no.
|
pascal@25564
|
606 %if CHSsanityCheck != 0
|
pascal@25564
|
607 cmp eax, 0FFFFh ; max cylinder = 1023
|
pascal@25564
|
608 ja SkipCHS
|
pascal@25564
|
609 %endif
|
pascal@25449
|
610 int 13h ; read sectors (AL, CX, DX, ES:BX)
|
pascal@25449
|
611
|
pascal@25449
|
612 jnc ReadSuccess ; CF = 0 if no error
|
pascal@25564
|
613 SkipCHS:
|
pascal@25449
|
614 %endif
|
pascal@25449
|
615 %if ReadRetry != 0
|
pascal@25458
|
616 %if CHSsupport != 0
|
pascal@25449
|
617 cbw ; ah = 0 = reset function
|
pascal@25458
|
618 %else
|
pascal@24945
|
619 xor ax, ax ; ah = 0 = reset function
|
pascal@25458
|
620 %endif
|
pascal@24476
|
621 int 13h ; reset drive (DL)
|
pascal@24476
|
622
|
pascal@25457
|
623 dec bp ; up to 32 retries
|
pascal@25454
|
624 jnz ReadSectorRetry
|
pascal@25449
|
625 %endif
|
pascal@24525
|
626
|
pascal@24476
|
627 call Error
|
pascal@24476
|
628 db "Read error."
|
pascal@24476
|
629
|
pascal@24478
|
630 ReadSuccess:
|
pascal@24476
|
631
|
pascal@24476
|
632 popa ; sp += 16
|
pascal@25564
|
633 popad
|
pascal@25564
|
634 mov dx, [bx(DriveNumber)] ; restore BIOS boot drive number
|
pascal@24476
|
635 ret
|
pascal@24476
|
636
|
pascal@25486
|
637 %if ExtraBootSector != 0
|
pascal@25486
|
638 MovedCode
|
pascal@25564
|
639 BootCode
|
pascal@25486
|
640 %endif
|
pascal@25486
|
641
|
pascal@24942
|
642 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24942
|
643 ;; Fill free space with zeroes ;;
|
pascal@24942
|
644 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24942
|
645
|
pascal@25458
|
646 times (512-13-($-$$)) db 0
|
pascal@24476
|
647
|
pascal@24476
|
648 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
649 ;; Name of the file to load and run ;;
|
pascal@24476
|
650 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
651
|
pascal@25463
|
652 NameLength equ 11
|
pascal@25463
|
653 ProgramName times NameLength db 0 ; name and extension
|
pascal@24476
|
654
|
pascal@24476
|
655 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
656 ;; End of the sector ID ;;
|
pascal@24476
|
657 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
658
|
pascal@25564
|
659 dw 0AA55h ; BIOS checks for this ID
|
pascal@25485
|
660
|
pascal@25485
|
661 %if ExtraBootSector != 0
|
pascal@25564
|
662 dd 61415252h ; "RRaA"
|
pascal@25564
|
663 BootFileName
|
pascal@25564
|
664 times (996-($-$$)) db 0
|
pascal@25564
|
665 ; dd 41617272h ; "rrAa"
|
pascal@25485
|
666 %endif
|