Re: Did Commodore cheat with the quad density floppies?

On Thu, Jan 3, 2019 at 3:39 PM Gerrit Heitsch <gerrit@laosinh.s.bawue.de> wrote:
>
> On 1/3/19 3:15 PM, Francesco Messineo wrote:
>
> > I remember nobody ever tried to find "QD" disks, normal DD 48TPI disks
> > were used (albeit I remember good quality brands were purchased
> > usually, like 3M, Olivetti).
>
> When I bought a whole lot of C64, 1541, an Amiga 2000A and some other
> stuff in 2011 for 20 Euros total on ebay (those were the days...), the
> lot also included about 500 floppy disks. When making D64 images from
> them, I came about a few QD disks, so they did exist

yes, I've never said the don't write SD/QD/DD on the boxes. I'm sure
they did, I have a few 96TPI DD boxes (BASF afair) myself, which seems
a contadiction, since DD was 48TPI :)
But anway, the media properties are all the same, 300 oersted is what
really matters (VS 600 oersted needed for the HD drives).
Lucky you anyway :)

>
>
> > There're two different issues on compact cassette:
> > 1) different (really much different) magnetic media, type I (Fe2O3,
> > iron oxide), Type II (CrO2), type III (FeCr), type IV (metal), these
> > media required different equalization and different recording
> > currents. Type I are usually very bad sounding and noisy, type IV have
> > the best quality, but the recorder really NEEDS to know what type of
> > tape it's trying to record into, otherwise you wouldn't get much
> > better results, unless maybe a bit less noise if you use a type IV
> > tape on a old, low quality recorder.
>
> Back when Type II was established, the type II tapes had an extra notch
> next to the erase control tab and most recorders had a sensor that
> detected the type that way. Wasn't something like this also added for
> type IV as well?

yes, every kind of compact cassette had different holes, but recorders
were not forced to auto-detect, my recorder in the '80s supported type
I and IV but had no autodetect, I needed to "inform" it via a switch
on what kind of cassette I had put in it.
The high end ones I'm sure had autodetect.
Frank