USB compatibility
#11
(08-07-2014, 03:40 PM)obo Wrote: I got writing working a few days ago for general MFM and FM formats, but haven't added pre-compensation yet. The documentation wasn't completely clear on how the bulk data for writes should be supplied, though I figured (correctly) it'd probably be the reverse of reading and require a RAM upload in advance.

I've a few extra questions too:

1) If the index is already active when an index-synchronised read/write is started, does the firmware wait for the start of the next index or start immediately?

2) Does the density setting control double-stepping tracks, or something else?

3) What difference does the 300 vs 360rpm make for reads and writes? Is it only for drives that support programmatic control of the motor speed?

4) Do you have any recommendations on when (if ever) the device needs resetting? Does closing and re-opening the device give a fresh session, or is it still possible there may be buffered data from a previous session?

Cheers Smile

Hi! Sounds like you are making progress. A DoCMD_ReadFlux() fills the RAM with the data from the track, which can then be transferred via the USB port or serial ports. DoCMD_WriteFlux() writes whatever length you want from the contents of the RAM. So, you need to transfer what you want to write to the RAM prior to doing the write command. For dual drives, you can read and write without doing a transfer at all because the RAM is holding the data.


Answers to your questions:

1) When a read or write command is issued, you can specify the ff_Index flag and that will wait for the index before the command starts. If the index pulse is low (active) when the command is issued, it waits for the start of the next index pulse. This guarantees that data always starts at the very beginning of the index pulse.

2) The density control is for changing between low density and density drive modes. This changes the drive hardware so it works with DD or HD types of disks.

3) Most all 1.2MB 5.25" drives can switch between 300RPM and 360RPM modes. Most do this when changing the density though, with DD using 300RPMs and HD using 360RPMs. Some drives have individual DD/HD and drive speed jumpers.

4) SCP never resets, and there is no need to reset it. The RAM contents remain the same until you power it off.
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Messages In This Thread
USB compatibility - by admin - 11-01-2013, 08:18 PM
RE: USB compatibility - by obo - 07-29-2014, 03:57 PM
RE: USB compatibility - by admin - 07-29-2014, 11:03 PM
RE: USB compatibility - by obo - 07-30-2014, 09:26 AM
RE: USB compatibility - by obo - 07-30-2014, 02:32 PM
RE: USB compatibility - by admin - 07-30-2014, 08:35 PM
RE: USB compatibility - by admin - 08-01-2014, 08:31 AM
RE: USB compatibility - by obo - 08-01-2014, 08:27 PM
RE: USB compatibility - by admin - 08-01-2014, 08:33 PM
RE: USB compatibility - by obo - 08-07-2014, 03:40 PM
RE: USB compatibility - by admin - 08-07-2014, 10:59 PM
RE: USB compatibility - by obo - 08-11-2014, 02:26 PM
RE: USB compatibility - by admin - 08-11-2014, 04:10 PM
RE: USB compatibility - by obo - 08-12-2014, 01:02 PM
RE: USB compatibility - by admin - 08-12-2014, 06:43 PM
RE: USB compatibility - by admin - 09-04-2014, 07:24 AM
RE: USB compatibility - by obo - 09-05-2014, 05:27 PM
RE: USB compatibility - by admin - 09-05-2014, 06:58 PM



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