Help with SCP and Atari 400/800 disks
#1
I have the SCP installation and setup completed using Win 10 with no issues, But I can't make a successful copy of an Atari unprotected disk using a good DS/DD Chinon 48 TPI disk drive.  (This PC drive came out of an Atari XF551, and works perfectly.) Two things are of concern:

1. After I get to track 20 (0-39), the drive starts "thumping" like it is trying to go past the 40th track. It does this on both read and write. After I make a copy of a regular Dos disk (all green on the GUI) and then try to boot that, it reads the first track and then goes into "Boot Error" and keeps trying to re-read the disk. This acts like SCP is making the drive double step, so it runs out of tracks at 20.  It is not set for 96 TPI.

2. On the settings, both READ and WRITE are set for High Density, with Low Density being "grayed out." Also the Backside setting has "None" grayed out. Nearly all Atari 8-bit disks are single-sided.

No Atari 8-bit drives are HD.  All 5-1/4" disks are 40 track, FM (SD) or MFM (DD).

Edit:
I've found the answers to part of my questions/issues. Evidently if a setting is checked, then that is what is set, even if grayed out. The non-grayed is an option.
So now on reading (in the copier/imager) I no longer get the thumping noise -- appears to stop at track 39.
But it still starts thumping at about track 20 when writing.
I've tried a half-dozen good single density disks that can be easily read on a stock Atari drive, but in every case, the resultant copy cannot be successfully booted.

I have looked at one with an Atari disk editor and reveals some issues.
1) SCP is reading every other track (or at least writing out every other track).
2) Every sector that is actually written is a bad sector. So only the first track is good and can be read when booting.

Thanks,
Larry
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#2
Make sure that you have the drive set to 48TPI in the pull-down menu if you are using a 48 TPI drive.
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#3
(08-27-2020, 01:08 PM)admin Wrote: Make sure that you have the drive set to 48TPI in the pull-down menu if you are using a 48 TPI drive.

It is (as best I can tell).  I am using a 48 TPI (DS/DD) drive.  The option for 5.25 -- 48 TPI is checked and shown in light gray.  The 5.25 -- 96 TPI is shown in black and white. (Pic attached).  I presume that the check mark means that it is the currently selected option.


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#4
Yes, that is correct. When it is in this mode, the drive will not double-step like it does when Atari 400/800 and 96 TPI is selected.
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#5
Here is a screen shot of the SCP copied disk tracks when read on a regular Atari 1050 drive (Archiver/Editor software).
Settings are as shown in the last pic. (48TPI). It seems to single step when reading, but then starts double stepping when writing. Only the first track is properly written. (Windows 10, BTW)


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#6
I thought of something that might cause this issue.

A regular Atari 8-bit drive is 288 rpm -- not the 300 standard for PC drives.  If the software does not compensate for this when writing, then the track will be too long.  Does the software compensate for the rpm difference?

The last drive that Atari made is the XF551 which had standard rpm of 300.  But the read and write is compensated in the firmware such that it is effectively 288 rpm and thus is compatible with all other drives.

I read another post in this forum that sounds a whole lot like my issue.

-Larry
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#7
There is no such thing as RPM with flux data. You can read or write the disk using different speed drives and the end result will be correct.

Stepping is a completely different matter. You seem to believe that there is no "chatter" when reading, but you believe there is when writing?
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#8
(08-28-2020, 02:28 AM)admin Wrote: There is no such thing as RPM with flux data.  You can read or write the disk using different speed drives and the end result will be correct.

Stepping is a completely different matter.  You seem to believe that there is no "chatter" when reading, but you believe there is when writing?

Near silence when reading (just the quiet noise of the head stepping); Bang, Bang Bang... when writing starting at track 20.  No mistaking the sound -- plenty loud.
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#9
Hmmm... it sounds like it is double-stepping on writes. I will look into it.
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#10
Thanks!
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