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10 November 2020, 13:11
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#1 |
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Registered User
Join Date: Apr 2009
Location: N/A
Posts: 962
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How does the system know that the floppy disk inserted is not the same?
I have two floppy disks, both have the same exact content and both have the same name. Both floppy disks have one application. I insert one floppy disk, open it, but before I start the application I remove the floppy disk and insert the other one and then start the application. When I do this I am told I need to insert the original floppy disk.
So my question is; how does the system know that the floppy disks are not the same when the two floppy disks have the same content and same name? |
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10 November 2020, 13:16
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#2 |
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Registered User
Join Date: Oct 2012
Location: Italy
Age: 49
Posts: 2,945
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Interesting question ....
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10 November 2020, 13:36
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#3 |
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son of 68k
Join Date: Nov 2007
Location: Lyon / France
Age: 51
Posts: 5,337
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It is because they don't have exactly the same content.
When a disk is copied with f.e. WB, some ID is changed. |
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10 November 2020, 14:47
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#4 |
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Going nowhere
Join Date: Oct 2001
Location: United Kingdom
Age: 50
Posts: 9,014
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Only way the disk is exact is if you use a track/sector copying program I.e. like X-Copy.
If you've used AmigaDOS and copied as files then it won't be exact, time stamps for instance will be different. |
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10 November 2020, 16:55
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#5 | |
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Registered User
Join Date: Dec 2018
Location: UK
Posts: 1,716
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Quote:
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10 November 2020, 17:17
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#6 |
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Registered User
Join Date: Dec 2018
Location: UK
Posts: 1,716
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Maybe Workbench also stores and checks other information about the floppy disk from the root block, which is where it gets the disk name from. If certain fields of the root block are different then that is possibly how it knows that it is a different disk.
https://wiki.osdev.org/FFS_(Amiga)#Root_Block And the file / directory structure will also probably be differrent (unless you did an exact image copy). |
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10 November 2020, 17:33
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#7 |
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Registered User
Join Date: Apr 2018
Location: Stockholm / Sweden
Posts: 129
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AmigaDOS has a list of all the current volumes in the system. The volume data structure is described here. As you can see, the data structure contains the name of the volume, the type of disk, and the volume creation date. The volume creation date is obtained from the root block of the disk's file system. AmigaDOS compares the volume's creation date and name to see if a newly inserted volume is already in the list. Probably the volume creation date differs between your two disks.
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10 November 2020, 17:35
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#8 |
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Registered User
Join Date: Oct 2012
Location: Italy
Age: 49
Posts: 2,945
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Thanks Niklas .... wonderful explanation
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11 November 2020, 10:16
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#9 |
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Registered User
Join Date: Apr 2009
Location: N/A
Posts: 962
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Thank you all for the replies. I always wondered how it worked in the background.
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