On Sat, 29 Mar 2008 14:36:11 +0000, =?UTF-8?B?Sm/Do28gSmVyw7NuaW1v?=
<spamtrap@[EMAIL PROTECTED]
> wrote:
>Dirk Wolfgang Glomp wrote:
>>>> But if you write your own HD-driver, the physical CHS-limit is:
>>>> 16 heads, 255 sectors, 65536 tracks(cylinders), and this gives
>>>> us 267386880 sectors (= 127.5 GB).
>>>> So if the the hardware can handle it then it works almost like LBA28
>>>> (max= 128 GB), ...except for the unconvenient calculation needs.
>>> But is this a DOS or a BIOS level driver?
>>
>> If you write the driver for DOS it´s a DOS-driver, else if you write
>> it for your own OS maybe you can call it BIOS-driver?
>
>Nop. But I don't know whether DOS can have it's own drivers to control
HDs.
>DOS usually calls the BIOS, so one can replace the BIOS HD driver and
have
>DOS call it, thinking it's the original BIOS driver.
>
>Did you understand, or need more explaining?
>
>JJ
>
If you replace the INT 13h vector with a vector to your own
handler, you would effectively have a "DOS driver". I have done this
long ago for a different reason than drive size: The DOS INT 13h shut
off all interrupts during transfers to disk, but I needed to respond
to A/D sample interrupts on non-DMA data acquisition systems,
in order to allow Direct-to-Disk recording. My INT 13h was pretty
much an ordinary CHS type, except it allowed the sample interrupts to
pass through during the block moves. Worked great: There was no
problem with sample rates of more than 100 kHz. Above about 120 kHz
the sample timing was adversely affected, so I never tried to go
higher to see if or when disk transfers might have suffered.
Best regards,
Bob Masta
DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
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