FDD-Problem

[joachim_neu]

hi everybody,

i've a problem with FDD. i wrote a driver and i was happy, when i saw my driver running in bochs. but after checkin in real i realized: it doesn't run. i don't know why!!! what's the big difference between bochs and the PC? i'd be happy if you'd spend some time to check my code. the important funktions are "FDDReadSektor" and "FDDWriteSektor". from there are calls made and it'll be easy to follow the code.
(its attached!)

mfg
J!N

[distantvoices]

Haven't the possibility nor time to scan throu all your code, so I gonna give you some hints:

1. Ports correct? (I know I know it works in the bochs)

2. Timeouts present? the floppy controller chip is a slow beast. You need to give it some time to act. Bochs (any emulator) doesn't need such timeouts.

Erm ... Have I said already that you 're a lucky lad? Having managed to get a fdc driver working in the bochs is quite some achievement. I've managed to get it running on real hardware PRIOR to bochs & qemu!! And imagine this for the sake of testing file system development .

conclusion: it is my bet that you need to introduce some waits ere writing to fdc registers. Haven't checked for that thou' so pls forgive me if I have sinned.

[joachim_neu]

and how long do you think for this operations:

-seek
-read/write
-register use

? thank you.

J!N

[distantvoices]

The fdc controller tells in its status register, if it is ready or not. Have a search for fdc programming in this forum or look at www.mega-tokyo.com/osfaq2 or at www.osdever.net. I don't know the needed instructions by heart. :p

read write reset seek f. ex. require yu to wait for fdc irq nr 6.

[joachim_neu]

one problem is also that the irq is only activated with the seek-command. there i'm waiting for it, but in read and write it doesn't activate an IRQ, i don't know, why...

[Pype.Clicker]

might you be missing some event acknowledge (sending EOI, or maybe something FDC-specific that you should do in order to tell the floppy "okay, i'm done with the event you report.")

[Dex4u]

Here are some pointers as the code is not commented in a language i understand.
1. Do you do a FddReSet on first using your floppy driver ?
2. Do you let motor get up to speed before a read/write command
3. Do you do call FddRecalibrate
4. Do you read ST0, ST1,ST2 ,etc, at end of your commands like
"FddRecalibrate","FddReadWrite",etc.

[joachim_neu]

well,

1. i call FDDReboot.
2. the motor gets 512 millisecs to speed up.
3. no, i don't call FDDRecalibrate. is it important?
4. i fetch the returnbytes but i trash them. i think if there's a temporary error it wouldn't occur 3 times, because that's the number i call the functions to load my keymap and my bitmapfont.

J!N

[Curufir]

3. no, i don't call FDDRecalibrate. is it important?

Well the HUGE difference between the BOCHS emulation and a real floppy is that the BOCHS drive never gives errors. However on a real floppy it's quite usual to require a few resets even with a perfectly good disk.

[Dex4u]

I have uploaded the fasm code for my asm OS called "Dex4u" in it is the asm code for a full working pmode floppy driver, along with working pmode CLI ,which includes commands like Dir etc.
You can take alook to see were yours differs, also in there is a fully working ATAPI driver (CD/DVD), if you OS does not have a working CD driver, here you chance to get one.

http://board.flatassembler.net/topic.php?p=23904#23904

[joachim_neu]

well,

first thank you. fasm-board seems to be offline at the moment. thank you for the code i'll check it. but i won't take your driver f?r ATA i'll only keep it for the next problems that'll come but i'll like to code everything on my one.

J!N