I am writing a small program to zap (zero out) HDDs.

Currently, I use ah=03h_int13h to do the job.
It works but it is kind of slow - 37 minutes to finish a 6GB HDD.

Just wonder if there is any faster way.

Thanks,
YONG

write your own DMA routine. I don't know exact way, but google for something like "DMA HDD access" or "DMA harddisk acces" or so...

I'll make some digging about DMA programming.

Thank vid for the input.

YONG

hope to use your utility to zero out some "financial transaction recorded" hard disk here

Sounds like something that should use DOD quality zapping...

Helo,

zap out harddisk?

its not a really complicated task,
you can boot from dos floppy, and start some code that uses direct I/O, via port, DMA is usually slower BUT working in background!
i wanted to use port to read write my harddisk, but since i could only use my program in dos, i stayed with bios.
i have attached some docs on Port access
Ralph Brown's port list Whole of it !

i think its enough to upload this file here once

if you make use of it let me know, i'm interested too
i can help if needed.

Ralph Brown's Port List (full) link at - DOS Frequently Asked Questions (FAQ)

Here are some findings of my digging:

DMA programming:
http://www.isdaman.com/alsos/hardware/dma/
- Technical spec., basic concepts, example in C, etc.

Direct I/O access, via ports, to HDDs:
http://board.flatassembler.net/topic.php?t=25
- Code: IDE PC Bootloader for 386+
- Routine "HD_Read" is a good example which shows how to
directly read from a HDD using I/O ports

Using direct I/O, my zap program again takes about 37 minutes
to finish the 6GB HDD. It seems that in this scenario,
direct I/O access and BIOS (INT13h) differ very little in speed.

Matrix:
The file PORTS.LST is extremely useful.
Why not add a link to the file in the FAQs?
Links to all Ralf Brown's gems would be great.

Thank vbVeryBeginner, f0dder, and Matrix for the input.

YONG