Hard sector format

HxC Floppy emulator support for all others computers...
Post Reply
djones60
Posts: 18
Joined: Wed Jun 13, 2018 2:59 pm

Re: Hard sector format

Post by djones60 » Tue Jul 10, 2018 10:31 pm

It's been quite for a while. So I'm curious, has there been any progress? Anything I can do to help?

snhirsch
Posts: 160
Joined: Tue Dec 08, 2015 1:42 am

Re: Hard sector format

Post by snhirsch » Tue Jul 10, 2018 11:42 pm

I was wondering the same thing. Jeff?

dwight
Posts: 11
Joined: Thu Jun 14, 2018 3:04 am

Re: Hard sector format

Post by dwight » Wed Jul 11, 2018 3:07 am

Hi
I've brought one of my North Star machines with 2 floppy drives, to a working state. I have a Gotek and know how to bootstrap code into it. I understand low level code as well. I'm not much of a C programmer though. I have my processor card working with a EPROM that would allow me to run low level code without having to have a booted disk in the system. I might be able to help some.
Dwight

Jeff
Site Admin
Posts: 6944
Joined: Fri Oct 20, 2006 12:12 am
Location: Paris
Contact:

Re: Hard sector format

Post by Jeff » Wed Jul 11, 2018 9:13 am

Maybe i wasn't clear enough in my explanations, but the current firmware implementation can't work properly with hard-sectored machine with such very short index signal timeout, especial for the write support. So i need to start an almost completely new firmware for this machine (the floppy data flow pipe need to be "redesigned"). And not having the machine is a serious problem for this work.

I am wondering one thing : Why not change the timeout value on the machine itself, or ignore the timeout events by software ? (need to patch the eprom content & the software ?)

snhirsch
Posts: 160
Joined: Tue Dec 08, 2015 1:42 am

Re: Hard sector format

Post by snhirsch » Wed Jul 11, 2018 3:23 pm

Jeff wrote:
Wed Jul 11, 2018 9:13 am
Maybe i wasn't clear enough in my explanations, but the current firmware implementation can't work properly with hard-sectored machine with such very short index signal timeout, especial for the write support. So i need to start an almost completely new firmware for this machine (the floppy data flow pipe need to be "redesigned"). And not having the machine is a serious problem for this work.

I am wondering one thing : Why not change the timeout value on the machine itself, or ignore the timeout events by software ? (need to patch the eprom content & the software ?)
I was wondering about this myself. With the current firmware, how much slack do you need at the end of sector data? Is it needed after every sector, or just start of new track?

djones60
Posts: 18
Joined: Wed Jun 13, 2018 2:59 pm

Re: Hard sector format

Post by djones60 » Wed Jul 11, 2018 4:51 pm

Even being able to only read disk images would be a help. That would at least let people bootstrap an old machine.

snhirsch
Posts: 160
Joined: Tue Dec 08, 2015 1:42 am

Re: Hard sector format

Post by snhirsch » Wed Jul 11, 2018 8:31 pm

djones60 wrote:
Wed Jul 11, 2018 4:51 pm
Even being able to only read disk images would be a help. That would at least let people bootstrap an old machine.
Heath read operation is implemented right now and works reliably. Northstar read is still in test mode and works about 95% of the time. If we can stretch out the "missed sector pulse" timer, it might work 100%.

dwight
Posts: 11
Joined: Thu Jun 14, 2018 3:04 am

Re: Hard sector format

Post by dwight » Thu Jul 12, 2018 10:27 pm

Hi
Making it ignore sector pulse overflow is not a trivial operation. Some of the code for the controller is in fused ROMs on the controller board. The rest is on the floppy. One still needs to supply data right after the sector pulse, even if one has no data. One can gain time though by corrupting the checksum. The OS allows two or three bad reads before it errors out. Depending on how it does this, that could be a delay of up to two revolutions of the disk. I'll try to look into this.
Another part of the difficulty is supplying the index pulse. I'm thinking this could more easily be handled with an extra timer. One could combine the extra pulse by setting open drain on the two timer outputs and wire them together. I don't think any of us would complain about adding a wire.
So, Jeff, are you supplying the sector pulses directly from timers or indirectly from software. I believe it would be best directly from the timers.
One could have an interrupt on the sector pulse. One could supply data with a bad checksum when not ready and good data when ready. Surely it can get the data from the USB within a couple of rotations for the disk.
Dwight

Jeff
Site Admin
Posts: 6944
Joined: Fri Oct 20, 2006 12:12 am
Location: Paris
Contact:

Re: Hard sector format

Post by Jeff » Wed Jul 18, 2018 7:23 pm

Got some ideas to try to fool the machine. I will provide some images to test ;)

dwight
Posts: 11
Joined: Thu Jun 14, 2018 3:04 am

Re: Hard sector format

Post by dwight » Wed Jul 18, 2018 10:49 pm

Hi Jef
Your in France, right? I can try to locate someone in your area with a machine to run test on.
Dwight

snhirsch
Posts: 160
Joined: Tue Dec 08, 2015 1:42 am

Re: Hard sector format

Post by snhirsch » Wed Jul 18, 2018 11:06 pm

dwight wrote:
Wed Jul 18, 2018 10:49 pm
Hi Jef
Your in France, right? I can try to locate someone in your area with a machine to run test on.
Dwight
That would be great, Dwight. Either an Advantage or Horizon with DD controller should function as a test bed.

Jeff
Site Admin
Posts: 6944
Joined: Fri Oct 20, 2006 12:12 am
Location: Paris
Contact:

Re: Hard sector format

Post by Jeff » Thu Jul 19, 2018 2:57 pm

dwight wrote:
Wed Jul 18, 2018 10:49 pm
Hi Jef
Your in France, right? I can try to locate someone in your area with a machine to run test on.
Dwight
Yes France - Paris.

djones60
Posts: 18
Joined: Wed Jun 13, 2018 2:59 pm

Re: Hard sector format

Post by djones60 » Thu Jul 19, 2018 3:01 pm

I have a working Advantage if you need a guinea pig to test it with. But I'm in the USA if that matters.

David

snhirsch
Posts: 160
Joined: Tue Dec 08, 2015 1:42 am

Re: Hard sector format

Post by snhirsch » Thu Jul 19, 2018 3:05 pm

djones60 wrote:
Thu Jul 19, 2018 3:01 pm
I have a working Advantage if you need a guinea pig to test it with. But I'm in the USA if that matters.

David
David, I have a working Advantage (and DD Horizon) and am already involved with testing here in the US. But, it would certainly be more effective if Jeff can get his hands on one in France. If I were wealthy, I'd consider shipping over my spare Advantage. Best guess is it would run in excess of 1000 USD to make the round trip... I'm a dedicated hobbyist, but not that dedicated :D.

djones60
Posts: 18
Joined: Wed Jun 13, 2018 2:59 pm

Re: Hard sector format

Post by djones60 » Thu Jul 19, 2018 3:30 pm

LOL. Dedicated hobbyist is one thing. Crazy or rich is another:)

I just thought I'd offer since I wasn't sue what all was available on this forum for testing.

David

Post Reply