ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://freenode.irclog.whitequark.org/~h~yamahasynths
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<whitequark>
so i'm thinking about shingled magnetic recording on floppies
<whitequark>
as far as i can tell the erase head can be simply defeated as the erase head driver is a simple open collector output buffer
<whitequark>
i.e. all it does is magnetize the entire track in one direction
<Lord_Nightmare>
it may work. the kodak 3.3mb/6mb/12mb floppies used a two-stepper system using cats-eye marks before every sector on a track, and a coarse and fine stepper
<Lord_Nightmare>
at least for the 3.3mb version i think it had well over 192TPI
<Lord_Nightmare>
and likely even more for the 6mb and 12mb versions
<Lord_Nightmare>
the annoying thing about the cats eye marks is that a disk cannot be reformatted in the drive itself, it has to be done from factory
<whitequark>
cats eye marks?
<Lord_Nightmare>
like you'd see on a calibration disk for a 5.25 or 3.5 drive
<whitequark>
i've never seen those
<Lord_Nightmare>
i think what a cats eye mark is is two sine waves encoded as flux on the disk, one a bit too far in for a specific track and another a bit too far out
<Lord_Nightmare>
and you adjust the drive calibration until the head amp read signal shows both peaks equal height
<Lord_Nightmare>
i think the two signals are 180 degrees out of phase
<Lord_Nightmare>
whitequark: if you figure out how to MAKE a cats-eye disk (possibly with 2 passes of writing in two deliberately misaligned drives) that would be very neat
<Lord_Nightmare>
but i don't know if it is necessary, there seem to be enough NOS alignment disks on ebay to go around I think
<Lord_Nightmare>
that 5.25 dymek disk is for a 48tpi drive
<Lord_Nightmare>
I think you can find a 96tpi 5.25 alignment disk on ebay too tho, lemme see if i can find one
<Lord_Nightmare>
maybe not... i don't see any for sale right now.