hardware interaction in c

vineetwadwekar · 03-28-2002, 12:58 PM

hi there,
this is vineet.i am in MCA fourth sem.planning to submit "system manager for dos" as a minor project,which would provide a GUI for formatting(A drive),scanning and many other utilities.but i am facing a lot of problems.it would be really nice of u if u could help me with the following..

1-->how can i provide information about all the partition's on the sytem i.e. it's free and used space.

2-->How can i show exat RAM size used(it's 192 in mine).

3-->it would be really nice of u if u could provide me information about media discreptor of floppy(1.44MB).

vineet..

GaPe · 03-28-2002, 01:44 PM

At first you should write what compiler do you use and in which operating system are you writing your code.

Shiro · 03-28-2002, 02:38 PM

>system manager for dos

I assume you're using DOS. You could use the info in the BIOS.

Nutshell · 03-28-2002, 11:55 PM

How can i use the info in the BIOS? DOn't u need assembly stuff do access the partition table and things like that?

vsriharsha · 03-29-2002, 01:19 AM

> How can i use the info in the BIOS? DOn't u need assembly stuff do access the partition table and things like that?

In the first case, No assembly is required to access partition table information and any of the Hardware resource information for that matter. C (I use Turbo C) provides u a rich set of functions to do the same for some and for the others u always have memory under ur spell, so get the values from various memory locations. U can also have information from CMOS using the system CMOS ports 70h & 71h.
For partition table...

The hard disk is partitioned using utilities like DOS's FDISK. While partitioning the hard disk, FDISK stores the details like where one partition ends and the next begins, which is the bootable partition etc in the first physical sector (side 0, track 0 sector 1). It also stores a program called Master Boot Program in the PT (partition table). Thus a PT consists of a data part and the code part. This is how the PT is logically divided...

Code Part Data Data 55
(master boot program) data data AA
-------------- ----------------------- -----------
446 bytes 64 bytes 2 bytes
totally : 512 bytes

The data part begins at the 447th byte. the last 2 bytes in the PT are always 0x55, 0xAA. The data part is 64 bytes long and is further divided into 4 16-bit chunks. Each chunk consists of info abt a partition on the HDD. Hence there can be maximum four partitions on the HDD. (dont confuse with logical drives which can by any number). The break up for those 16-byte chunks are ...

Byte Meaning
----- -----------
0 Boot Indicator. Contains 0x80 for active partition and 0
otherwise.Only 1 partition can be active at a time
1 Side where partition begins
2 Low-six bits are the sector where partition begins
Two-high bits are the two high bits of the track where
partition begins
3 Low order 8 bits of the track where partition begins
4 Partition type indicator. The following values may exist...
0 - Unused partition
1 - DOS partition using 12-bit FAT
2 - Unix Partition
4 - DOS partition using 16-bit FAT
5 - Extended partition
6 - Huge Partition
5 Side where partition ends
6 Low-six bits are the sector where partition ends
Two-high bits are the two high bits of the track where
partition ends
7 Low order 8 bits of the track where partition ends
8-11 Double word containing the number of sectors preceding
the partition. Low order word is stored first
12-15 Double word containing the number of sectors in
the partition. Low order word is stored first

So, with these details, go ahead and try a program off ur brains... But remember (There is no mention for 32-bit FAT or Linux native / swap partitions. So, this is a premitive stuff (not suited for the latest partitions), so just be careful)

Best regards,
Sriharsha.

*Note: Dont play with ur PT or else U have to reset the whole disk.

Nutshell · 03-29-2002, 01:30 AM

What are the functions that can access the partition table?

vsriharsha · 03-29-2002, 09:01 AM

I never remember using any Off-the shelf functions. I always wrote it on my own.
I guess u can do it with the info i provided above.

03-28-2002, 12:58 PM	#1
vineetwadwekar Registered User Join Date: Mar 2002 Posts: 1	hardware interaction in c hi there, this is vineet.i am in MCA fourth sem.planning to submit "system manager for dos" as a minor project,which would provide a GUI for formatting(A drive),scanning and many other utilities.but i am facing a lot of problems.it would be really nice of u if u could help me with the following.. 1-->how can i provide information about all the partition's on the sytem i.e. it's free and used space. 2-->How can i show exat RAM size used(it's 192 in mine). 3-->it would be really nice of u if u could provide me information about media discreptor of floppy(1.44MB). vineet..
vineetwadwekar is offline

03-28-2002, 01:44 PM	#2
GaPe Code Warrior Join Date: Nov 2001 Posts: 669	At first you should write what compiler do you use and in which operating system are you writing your code. __________________ Current projects: 1) User Interface Development Kit (C++) 2) HTML SDK (C++) 3) Classes (C++) 4) INI Editor (Delphi)
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03-28-2002, 02:38 PM	#3
Shiro .... Join Date: Aug 2001 Location: Groningen (NL) Posts: 2,386	>system manager for dos I assume you're using DOS. You could use the info in the BIOS.
Shiro is offline

03-28-2002, 11:55 PM	#4
Nutshell Registered User Join Date: Jan 2002 Posts: 1,020	How can i use the info in the BIOS? DOn't u need assembly stuff do access the partition table and things like that?
Nutshell is offline

03-29-2002, 01:19 AM	#5
vsriharsha Im a Capricorn Join Date: Feb 2002 Posts: 192	> How can i use the info in the BIOS? DOn't u need assembly stuff do access the partition table and things like that? In the first case, No assembly is required to access partition table information and any of the Hardware resource information for that matter. C (I use Turbo C) provides u a rich set of functions to do the same for some and for the others u always have memory under ur spell, so get the values from various memory locations. U can also have information from CMOS using the system CMOS ports 70h & 71h. For partition table... The hard disk is partitioned using utilities like DOS's FDISK. While partitioning the hard disk, FDISK stores the details like where one partition ends and the next begins, which is the bootable partition etc in the first physical sector (side 0, track 0 sector 1). It also stores a program called Master Boot Program in the PT (partition table). Thus a PT consists of a data part and the code part. This is how the PT is logically divided... Code Part Data Data 55 (master boot program) data data AA -------------- ----------------------- ----------- 446 bytes 64 bytes 2 bytes totally : 512 bytes The data part begins at the 447th byte. the last 2 bytes in the PT are always 0x55, 0xAA. The data part is 64 bytes long and is further divided into 4 16-bit chunks. Each chunk consists of info abt a partition on the HDD. Hence there can be maximum four partitions on the HDD. (dont confuse with logical drives which can by any number). The break up for those 16-byte chunks are ... Byte Meaning ----- ----------- 0 Boot Indicator. Contains 0x80 for active partition and 0 otherwise.Only 1 partition can be active at a time 1 Side where partition begins 2 Low-six bits are the sector where partition begins Two-high bits are the two high bits of the track where partition begins 3 Low order 8 bits of the track where partition begins 4 Partition type indicator. The following values may exist... 0 - Unused partition 1 - DOS partition using 12-bit FAT 2 - Unix Partition 4 - DOS partition using 16-bit FAT 5 - Extended partition 6 - Huge Partition 5 Side where partition ends 6 Low-six bits are the sector where partition ends Two-high bits are the two high bits of the track where partition ends 7 Low order 8 bits of the track where partition ends 8-11 Double word containing the number of sectors preceding the partition. Low order word is stored first 12-15 Double word containing the number of sectors in the partition. Low order word is stored first So, with these details, go ahead and try a program off ur brains... But remember (There is no mention for 32-bit FAT or Linux native / swap partitions. So, this is a premitive stuff (not suited for the latest partitions), so just be careful) Best regards, Sriharsha. *Note: Dont play with ur PT or else U have to reset the whole disk. __________________ Help everyone you can
vsriharsha is offline

03-29-2002, 01:30 AM	#6
Nutshell Registered User Join Date: Jan 2002 Posts: 1,020	What are the functions that can access the partition table?
Nutshell is offline

03-29-2002, 09:01 AM	#7
vsriharsha Im a Capricorn Join Date: Feb 2002 Posts: 192	I never remember using any Off-the shelf functions. I always wrote it on my own. I guess u can do it with the info i provided above. __________________ Help everyone you can
vsriharsha is offline

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