Questions about HxC software

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Radiorama
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Joined: Mon Jan 18, 2021 9:51 am

Questions about HxC software

Post by Radiorama »

Hi Jeff and everyone,

I have a set of questions about the HxC Floppy Emulator software. I apologise if they have been answered elsewhere, but I couldn't find any answer anywhere. Please bear with me.

1. In track view mode, I reckon that the blue line above shows index pulses, while a red band just below that means a flakey/non-flux area, right?
But what is represented on the Y axis? There are more or less horizontal jagged grey lines on a microsecond scale, but I can't figure out what they are. Right clicking on track view seems to add more grey pixels, that occasionally break data encoding.

2. How long is a cell exactly? The SCP format doc says it's a set of 16 or 8 bits, but in HxC it seems way smaller than that. For example, I have a disk image with 102092 cells per track at 300 rpm, which translates into a cell time of slightly less than 2 us.

3. I can't find any documentation about the track editing tool. I think I more or less got most of it, but there are a few obscure functions/behaviours and, once again, I couldn't find a manual.
- What does Shift Tracks do? I guess it's like Shift but applies to all tracks simultaneously, right? What I don't get is why it sems to shift tracks by a number of cells equal to 104 times the number written in the box to the right.
- What does Rapair do?
- What does direct edition do?

Thanks in advance for any explanation.

Best,
Radiorama

Jeff
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Re: Questions about HxC software

Post by Jeff »

Radiorama wrote:
Mon Jan 18, 2021 10:43 am
1. In track view mode, I reckon that the blue line above shows index pulses, while a red band just below that means a flakey/non-flux area, right?
yes
Radiorama wrote:
Mon Jan 18, 2021 10:43 am
But what is represented on the Y axis? There are more or less horizontal jagged grey lines on a microsecond scale, but I can't figure out what they are. Right clicking on track view seems to add more grey pixels, that occasionally break data encoding.
These are the data pulses coming from the drive. At each magnetic flux reversal a pulse is generated by the drive.
(See https://www.youtube.com/watch?v=DdMOGvKjrfk)
Radiorama wrote:
Mon Jan 18, 2021 10:43 am
2. How long is a cell exactly? The SCP format doc says it's a set of 16 or 8 bits, but in HxC it seems way smaller than that. For example, I have a disk image with 102092 cells per track at 300 rpm, which translates into a cell time of slightly less than 2 us.
This depend : An MFM HD / 500Kbits disk have 2 us, 3us and 4us pulse. Take the minimum value (2us in this case) and divide it by two to have the cell period (1us). Note : The software is working internally on a 250MHz bitstream to analyse the dump (the streams are upscaled at the importation/loading).
Radiorama wrote:
Mon Jan 18, 2021 10:43 am
3. I can't find any documentation about the track editing tool. I think I more or less got most of it, but there are a few obscure functions/behaviours and, once again, I couldn't find a manual.
- What does Shift Tracks do? I guess it's like Shift but applies to all tracks simultaneously, right? What I don't get is why it sems to shift tracks by a number of cells equal to 104 times the number written in the box to the right.
Yes this rotate the track. The value is in "per-thousand" of the tracks lenght. (This will probably change in a next version).
Radiorama wrote:
Mon Jan 18, 2021 10:43 am
- What does Rapair do?
This is a "brute force" feature to try to fix a sector. All the cells combinations between the 2 markers are tried until a good crc / checksum is found. Don't expect to be able to fix an heavily damaged sector with this... But this is working pretty good to fix a spot in a sector (Max window size of ~24 cells).
Radiorama wrote:
Mon Jan 18, 2021 10:43 am
- What does direct edition do?
It allows you to manually set/clear cells. (This is what you have done : <<Right clicking on track view seems to add more grey pixels, that occasionally break data encoding.>>

Radiorama
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Joined: Mon Jan 18, 2021 9:51 am

Re: Questions about HxC software

Post by Radiorama »

Wow, really a very comprehensive reply! Thanks Jeff!

And now for the really dumb question: what does HxC stand for? Hardcore, perhaps? But why? :)

Best,
Radiorama

Jeff
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Joined: Fri Oct 20, 2006 12:12 am
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Re: Questions about HxC software

Post by Jeff »

Radiorama wrote:
Mon Jan 18, 2021 11:06 pm
Wow, really a very comprehensive reply! Thanks Jeff!

And now for the really dumb question: what does HxC stand for? Hardcore, perhaps? But why? :)

Best,
Radiorama
Yes exactly. This is a 23/24 years old story. HxC was the name chosen with some friends to make an hacker/cracker/demo group... I just still use it :lol:.

Radiorama
Posts: 8
Joined: Mon Jan 18, 2021 9:51 am

Re: Questions about HxC software

Post by Radiorama »

Last question, I promise :D

What does the number in the box under the Direct edition button do? The default is 010, but I can't see any difference in behaviour when I change it.

Thanks, the more I use it, the more pieces fall into place, the more I appreciate how powerful this program is.

-- R

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