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Kratznagel
Account closed
Registered: Aug 2005
Posts: 4 |
Searching for a fast-writing floppy routine
Hi there,
I am searching for a special floppy routine for the 1541 which I can use as a replacement for the CBM-DOS block-write command. Of course it should be faster than the original one. ;)
Can somebody help me out?
CU
Kratznagel |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
A static gap is not perfectly safe since different drives have different spinning speeds. |
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tlr
Registered: Sep 2003
Posts: 1714 |
Quote: A static gap is not perfectly safe since different drives have different spinning speeds.
Ofcourse, but the speed should be close to 300 rpm if the drive is properly calibrated. If not, it is probably time to calibrate it.
I agree though that it would be better to measure the track. Have a look at how SpeedDOS does it. This formatter is just as fast as mine, and manages to measure aswell. I guess it makes the assumption that the floppy rotates at a constant speed, which is a fair assumption. This way it needs to measure only once. Also it has been proven in "battle" as I stated earlier. :) |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Hardly any drive really has those theoretical 300 rpm. It ranges from 280 to 320 rpm. And in the future this problem is getting bigger since the spinning speeds get more and more uncalibrated. Also, some mechanics used for the 1541 had a default of ~280 rpm and not 300. |
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TNT
Account closed
Registered: Oct 2004
Posts: 189 |
Where do you get your drives from? I have tested eight drives and all of them have rotated between 295 and 305 RPM. Drives have ranged from Japan-made VC-1541 with original long board to C128D's internal 1571. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
One of my C128DCR drives has ~320 rpm, and I know that commodore used some 285 rpm mechanics in some 1541.
Anyway, even 295-305 is enough, 305 rpm has a tracklength of 7566 gcr bytes on a track and 295 rpm has a tracklength of 7822 gcr bytes. This makes a difference of 263 bytes in total or 12.5 bytes per sector gap!
Take for example this fast format routine with a default of 8 bytes sector gap: A sector has the size of 5+10+10+5+325+8 gcr bytes = 363. A track would be 363*21 = 7623... 57 bytes longer than a track on a 305 rpm drive, so the last sector overwrites 57 bytes of the first again -> format routine does not work at all on such drive. |
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Steppe
Registered: Jan 2002
Posts: 1510 |
Sorry for zombifying that thread, but is there a software I can use to measure my drive rotation speed? |
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Devia
Registered: Oct 2004
Posts: 401 |
Yes. Try this
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Frantic
Registered: Mar 2003
Posts: 1627 |
Vice (x64, didn't try x64sc) gives me 356.5 RPM with this test program. :) Huhu.. |
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Mr. SID
Registered: Jan 2003
Posts: 421 |
1541U gives 357RPM. |
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Steppe
Registered: Jan 2002
Posts: 1510 |
Hehe, same here. Thanks for posting the link, Devia. Returns a healthy sounding 300.2 rpm for my 1571 in the 128 DCR. |
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