The Sinclair QL Forum

So I was refelting a bunch of microdrive cartridges and couldn't get two to format. I tried everything and must have cleaned the heads multiple times, etc. I even tried wiping any data off of them with a strong magnet thinking maybe a clean slate would do...but nothing. They were both write-protected, doh. I'm running JSU ROM. Does Minerva and/or SMSQ/E give a better error message then "format failed" since that doesn't lead you to think it's write protected.

I think Sinclair never completed wiring up the write protection switch, so the OS cannot tell the difference from format failed.

Yep, that's actually a hardware bug that never got fixed.

The Spectrum had a software write protection. If the software crashed it could still delete data, which apparently was not only a theoretical problem. The QL has only a hardware write protection, the QL could only check if it's active by writing and checking if anything has changed. But it's difficult to distinguish between that and a bad MDV. Given the space constraints of the ROM it was probably not worth the trouble. SMSQ/E solved this by simply not including any MDV support at all...

mk79 wrote:The Spectrum had a software write protection. If the software crashed it could still delete data, which apparently was not only a theoretical problem. The QL has only a hardware write protection, the QL could only check if it's active by writing and checking if anything has changed. But it's difficult to distinguish between that and a bad MDV. Given the space constraints of the ROM it was probably not worth the trouble. SMSQ/E solved this by simply not including any MDV support at all...

There is actually a provision in the 8049 for reading the write-protect status and even a system variable (SV.WP), but the pin that was to be used for it (37 or P26 on the 8049) isn't connected to anything...

I do not understand the issue ? Many removable media (mdvs, flps...) have hardware write protections (some kind of tabs) that you can see and manipulate. If you may modify them by (any) software, it means that you no longer have write protection. So, for these media, it is well that QDOS does not permit it.
Bye, POLKa (the Jedi is back ! you will hear from me soon)

polka wrote:I do not understand the issue ? Many removable media (mdvs, flps...) have hardware write protections (some kind of tabs) that you can see and manipulate. If you may modify them by (any) software, it means that you no longer have write protection. So, for these media, it is well that QDOS does not permit it.
Bye, POLKa (the Jedi is back ! you will hear from me soon)

The problem is that QDOS doesn't tell you why a format failed so if you don't check the cartridge to see if it is write protected (it's not obviously visible unless you turn the cartridge over and notice the tab broken off) you may think it's just bad. It happened to me for two of them until I accidentally stumbled on a QLForum post that pointed out the cartridge may be write protected (the tab broken off) so I checked and voila they were. Put some tape on it and both formatted and both now work. So it's just an inconvenience that QDOS doesn't tell you "MDV write protected" that's all. It is certainly nice that it doesn't overwrite anything.

OK, then the problem is only the suitability of the QDOS error/warning message. I misunderstood (because focusing on some answers to your first post) that you were complaining about the inability to override the hardware write protection through software.

Bye, POLKa