exxos's Atari, Amiga & retro forum

reading the wd1772 datasheet it says that 20 is used to enable the spindle. This is staying high when it gets to desktop.

Do you know what /CS should be doing? it pulses low once on 80ns scale

I don't know what timings anything has really.. you would have to check on a working ST and compare them all.

The ST does poll the drive like twice a second or something.. so likely CS goes low during those times.

Maybe my memory is foggy, but I always thought the drive would be damaged by plugging the cable in upside down. Something about voltages on the wrong pins that way. :?:

exxos wrote: 27 Sep 2018 16:23

exxos wrote: 27 Sep 2018 10:24 It might be worth scoping out some pins around ACIA area, such as (U54) A1 pin 11, A2 pin 8, (U32) pin 3 SNDCS.. (IC2 MFP) pin 48 CS.

Back to the plot...

Wow I go off grid for a day and see what happens. Great discussion on floppy controllers and drives though.

I’ll take a look at scoping out the signals later tonight.

TheNameOfTheGame wrote: 27 Sep 2018 19:13 Maybe my memory is foggy, but I always thought the drive would be damaged by plugging the cable in upside down. Something about voltages on the wrong pins that way. :?:

I have stuck drive cables in the wrong way many a time on an ST. I haven’t had one damaged but I could just be lucky.

Same for me and usually the drive light staying on is a key to it being the wrong way round (on a pc at least!)

Forgottenmyname wrote: 27 Sep 2018 19:18 Same for me and usually the drive light staying on is a key to it being the wrong way round (on a pc at least!)

Funny was about to say that’s my rule of thumb :)

Well joystick port works - have been playing Xenon II :)

exxos wrote: 27 Sep 2018 10:24 It might be worth scoping out some pins around ACIA area, such as (U54) A1 pin 11, A2 pin 8, (U32) pin 3 SNDCS.. (IC2 MFP) pin 48 CS.

In order on the scope as per your pins above:

(U54) A1 pin 11 - CH1, A2 pin 8 - CH2, (U32) pin 3 SNDCS - CH3, (IC2 MFP) pin 48 CS - CH4

Ah, you need to be on 5v/div on each... Also hold down a key to trigger sounds and acia...