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Bacchus
Registered: Jan 2002
Posts: 155 |
Drive code: Detect missing disk...
I have detecting missing *device* covered. This logics work really well:https://codebase64.org/doku.php?id=base:reading_the_error_chann..
Also, checking if a file exists, one would expect that a plain Open would do the job, but you basically need to read the first byte and checking the Status. But then you have established that.
But what is the easiest way to detect if the device contains a disk? Let's say we have established that there is a disk in the drive. I can start reading a file, but then I don't know if the error will tell me if the file or the entire disk is missing.
Should I do a block read, start reading the directory or what is the general suggestion?
/Bacchus |
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Comos
Registered: May 2004
Posts: 73 |
If you rely on the kernal calls, then using a directory routine and to read a valid byte and check $90 might do the trick. |
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Krill
Registered: Apr 2002
Posts: 2940 |
When using KERNAL calls only, reading the device's error channel is the only way to reliably tell the kind of error.
This is something else than "drive code", though. :) |
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chatGPZ
Registered: Dec 2001
Posts: 11290 |
Turn on the motor and wait for a sync (with timeout) - should be easy enough :) |
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Count Zero
Registered: Jan 2003
Posts: 1878 |
Quote: Turn on the motor and wait for a sync (with timeout) - should be easy enough :)
Zibri approves! *SCNR* |
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Bacchus
Registered: Jan 2002
Posts: 155 |
Quote: If you rely on the kernal calls, then using a directory routine and to read a valid byte and check $90 might do the trick.
So basically a getbyte from the filename "$", and one could tell already from the first byte if there was a byte or not?
I do know how to drivecode, but I want to select the route of the least resistance here.
/Bacchus |
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Comos
Registered: May 2004
Posts: 73 |
Quote: So basically a getbyte from the filename "$", and one could tell already from the first byte if there was a byte or not?
I do know how to drivecode, but I want to select the route of the least resistance here.
/Bacchus
Read just one byte and check bit 1 of $90, 1 = Timeout on read, which in simple would mean there is no disk inserted since we are accessing the lower level - the directory.
If you do this check on a file, then you won't be able to determinate, if the file is simply not present or there is no disk inserted,since in both cases you'll get the same bit set.
Ofcourse this method is not perfect for some detailed error handling.
If you would like to go the way to read out the error channel, then you have to do something in advance like running the init "I" command and then read out the error channel. |
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Count Zero
Registered: Jan 2003
Posts: 1878 |
Quoting BacchusSo basically a getbyte from the filename "$", and one could tell already from the first byte if there was a byte or not?
A drive such as a SD2IEC could easily fool for an inserted disc in such a case - so it likely depends on the used loader/saver compatibility in the end unless you determine the drivetype as well or stick to plain kernal routines. hm? |
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Krill
Registered: Apr 2002
Posts: 2940 |
The clean way is still to read the error channel.
Why is this not an option? :) |
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Mason
Registered: Dec 2001
Posts: 461 |
Sorry for my vague memory, but it's many years ago I did it
I reckon you can load a byte from a file or the directory. If it doesn't work I reckon $90 is set as a status |
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chatGPZ
Registered: Dec 2001
Posts: 11290 |
Quote:Why is this not an option?
head bump? |
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