DOS ain't dead - BIOS and memory

DOS386

25.08.2007, 02:47

BIOS and memory (Miscellaneous)

Japheth wrote (in other thread):

> However, modern BIOSes supporting SATA usually also support ultra DMA, so an external driver is not necessary.

Indeed ... seems to be pretty fast via INT $13 :-)

But how is it done ? They support DMA and USB storage - but where do they take the memory ? DMA drivers always need XMS, DOS USB drivers always have memory problems, and mostly do require XMS, or even worse EMM386 :-(

How do the new "dead" BIOS'es do "without" memory ? :-)

---
This is a LOGITECH mouse driver, but some software expect here
the following string:*** This is Copyright 1983 Microsoft ***

Japheth

Germany (South),
25.08.2007, 08:27

@ DOS386

BIOS and memory

Post reply

> But how is it done ? They support DMA and USB storage - but where do they
> take the memory ? DMA drivers always need XMS

No. A buffer - in XMS or EMS memory - is only needed if the source/destination address isn't DWORD aligned. And if no such buffer is available, the driver will use PIO mode.

---
MS-DOS forever!

DOS386

29.08.2007, 16:03

@ Japheth

BIOS and memory | no memory needed ?

Post reply

Thanks.

> No. A buffer is only needed if the source/destination address isn't DWORD
> aligned. And if no such buffer is available, the driver will use PIO mode.

Do you mean driver or BIOS here ?

Does it mean that BIOS can use DMA for almost no "cost" (RAM) ?

How can BIOS support USB (kbd, mouse, and storage), if it's that memory hoggy when using DOS drivers ?

---
This is a LOGITECH mouse driver, but some software expect here
the following string:*** This is Copyright 1983 Microsoft ***

Japheth

Germany (South),
30.08.2007, 07:38

@ DOS386

BIOS and memory | no memory needed ?

Post reply

> > No. A buffer is only needed if the source/destination address isn't
> DWORD
> > aligned. And if no such buffer is available, the driver will use
> PIO mode.
>
> Do you mean driver or BIOS here ?

the BIOS

> Does it mean that BIOS can use DMA for almost no "cost" (RAM) ?

Yes

> How can BIOS support USB (kbd, mouse, and storage), if it's that memory
> hoggy when using DOS drivers ?

Possibly there is large space for improvements in the current DOS USB drivers.

---
MS-DOS forever!

Jose Antonio Senna 09.09.2007, 23:59 @ Japheth	BIOS and memory \| no memory needed ? Post reply
	Would someone tell whether the boards which support USB in BIOS have specialized hardware or do use the CPU to provide the usb engine ? > Possibly there is large space for improvements in the current DOS USB > drivers. Or is it because almost all RAM is used by drivers for executable code ?

Berlin, Germany,
10.09.2007, 13:37

@ Jose Antonio Senna

BIOS and memory | no memory needed ?

Post reply

OT: Why do you not use your account "jassenna" for posting? Just curious.

---
Forum admin