Log inRegister an accountBrowse CSDbHelp & documentationFacts & StatisticsThe forumsAvailable RSS-feeds on CSDbSupport CSDb Commodore 64 Scene Database
You are not logged in - nap
CSDb User Forums


Forums > C64 Coding > Write a Disk backwards
2019-06-20 10:31
oziphantom

Registered: Oct 2014
Posts: 490
Write a Disk backwards

Is it possible to write a disk backwards, say take a D64 probably pre flipped and write it backwards. Maybe run the stepper motor backwards?
2019-06-20 10:45
Krill

Registered: Apr 2002
Posts: 2980
Write out a double-sided disk using 1571. There you go, backwards on 2nd side when flip-side inserted in a 1541. \=D/
2019-06-20 11:56
oziphantom

Registered: Oct 2014
Posts: 490
that gives you a backwards disk, but doesn't write it backwards.
2019-06-20 12:10
Krill

Registered: Apr 2002
Posts: 2980
Okay, so for the umpteenth time (cue link to Wikipedia "XY problem" article), what do you _actually_ want to achieve?
2019-06-20 12:16
iAN CooG

Registered: May 2002
Posts: 3193
Turn the 1541 upside down. =)
2019-06-20 12:18
oziphantom

Registered: Oct 2014
Posts: 490
To write a disk backwards, basically this gives the opposite of what you described. 1571 only the bottom image is the right way when you flip the disk.
2019-06-20 12:25
Krill

Registered: Apr 2002
Posts: 2980
My bad. Doesn't answer the question, though.
2019-06-20 12:30
oziphantom

Registered: Oct 2014
Posts: 490
I'll add more words

The goal is to write an image with the 1571 only to have the flip side be the right way when the disk is flipped, i.e consumed by a 1541.
2019-06-20 12:35
Krill

Registered: Apr 2002
Posts: 2980
And why would you want to do that? :)

Give us a user story! :D
2019-06-20 12:52
oziphantom

Registered: Oct 2014
Posts: 490
Say your a publisher, and you have a popular title that needs both sides of a disk, and you have a popular game on your hands and you have 1000 orders.

So put disk in 1541, tell it to write and verify the image.
Notice that it has finished, stop what you are doing ( folding a box, stapling a manual ), open the drive, flip the disk, close the hatch, start it on the 2nd side.
Go back to what you where doing.
Wait for the 1541 to write and verify the image.

VS

Put disk in 1571 and tell it to go.
Do more stuff while you wait for it to write and verify both sides of the disk.

The 2nd case is going to be a lot more efficient, and allow them to do the orders in less time. Might make a nice little solution to package up and sell to them ;)
2019-06-20 13:12
ChristopherJam

Registered: Aug 2004
Posts: 1409
Quote: I'll add more words

The goal is to write an image with the 1571 only to have the flip side be the right way when the disk is flipped, i.e consumed by a 1541.


Probably doable. You just need to flip all the bytes, reverse the buffers, do each sector before each sector header, and place the sync marks at the end of each write instead of the start. No idea if the alignment would be correct..

Start with a custom formatter, edit in those changes, and see if it works!
2019-06-20 13:29
Krill

Registered: Apr 2002
Posts: 2980
Yeah, a lot of ifs. Might or might not work.

But if you're really going to duplicate 1000 double-sided disks, you'd probably be better off rigging something together with a PC and Kryoflux or Catweasel.
2019-06-20 14:11
Mr. SID

Registered: Jan 2003
Posts: 424
Are you going to sell the 1571 drives as part of the solution? :)
2019-06-20 14:37
soci

Registered: Sep 2003
Posts: 480
Yes it is possible to write it backward but it will not work very well.

While the two heads are physically located above each other the coils are not.

Practically this means the 2nd side head can't reach some of the lower numbered track locations.

So there will be like 4 or 5 tracks worth of misalignment unless the inaccessible lower tracks are skipped and not written.

In my opinion avoiding the side flipping won't gain much as with a bit of practice the majority of time will be spent on writing and verifying the disks.
2019-06-20 22:08
bugjam

Registered: Apr 2003
Posts: 2589
I have to say I do like the idea. Pity it seems to face a lot of obstacles.
2019-06-21 07:49
oziphantom

Registered: Oct 2014
Posts: 490
Quoting soci
Yes it is possible to write it backward but it will not work very well.

While the two heads are physically located above each other the coils are not.

Practically this means the 2nd side head can't reach some of the lower numbered track locations.

So there will be like 4 or 5 tracks worth of misalignment unless the inaccessible lower tracks are skipped and not written.

In my opinion avoiding the side flipping won't gain much as with a bit of practice the majority of time will be spent on writing and verifying the disks.


Is this why the 1571 is 35 tracks only. In that its actually 40, just it uses the inner 35 on the top side and the outer 35 on the bottom?
RefreshSubscribe to this thread:

You need to be logged in to post in the forum.

Search the forum:
Search   for   in  
All times are CET.
Search CSDb
Advanced
Users Online
Alakran_64
Flashback
pcollins/Quantum
MWR/Visdom
Devia/Ancients
Freeze/Blazon
rambo/Therapy/ Resou..
katon/Lepsi De
Guests online: 150
Top Demos
1 Next Level  (9.7)
2 13:37  (9.7)
3 Mojo  (9.7)
4 Coma Light 13  (9.6)
5 Edge of Disgrace  (9.6)
6 What Is The Matrix 2  (9.6)
7 The Demo Coder  (9.6)
8 Uncensored  (9.6)
9 Comaland 100%  (9.6)
10 Wonderland XIV  (9.6)
Top onefile Demos
1 Layers  (9.6)
2 No Listen  (9.6)
3 Cubic Dream  (9.6)
4 Party Elk 2  (9.6)
5 Copper Booze  (9.6)
6 Rainbow Connection  (9.5)
7 Dawnfall V1.1  (9.5)
8 Onscreen 5k  (9.5)
9 Morph  (9.5)
10 Libertongo  (9.5)
Top Groups
1 Performers  (9.3)
2 Booze Design  (9.3)
3 Oxyron  (9.3)
4 Triad  (9.3)
5 Censor Design  (9.3)
Top Swappers
1 Derbyshire Ram  (10)
2 Jerry  (9.8)
3 Violator  (9.7)
4 Acidchild  (9.7)
5 Cash  (9.6)

Home - Disclaimer
Copyright © No Name 2001-2024
Page generated in: 0.05 sec.