Icky - Progress

rpineau · Post by **rpineau** » 14 Oct 2018 02:21

I like the idea of the buffer to isolate the 1772 to prevent data conflict.
I also like the idea of buffering the DMA port... but without delay on it.
This would protect the DMA chip, make the external DMA data more stable.
If you look a the schematics for some of the Atari hard drive, they do buffer the out port of these with some 74LS245 to the next device.
with /G wired to /HDCS and DIR to R/W , thus not adding delays on the DMA devices (besides the buffer propagation time).

Post by **exxos** » 14 Oct 2018 02:56

Yeah I saw Atari drives have the buffers, again odd that ste have same buffers again... I guess it could explain a little why Atari drives seemed to work better than 3rd party ones back in the day. I guess most issues were with pre-ste machines as I assume 3rd party drives may not have the buffers and could fail to function correctly.

Mostly thoughts are for ultrasatan. Jookie used resistor dividers on the io, so suspect a fair load on the io lines, so buffers would help there. But I don't know how later ones were done.. If they use resistors still or proper level translation chips..

I will probably add DMA buffers just to be sure anyway. Taking load away from the DMA can only be a good thing. And of course buffer to isolate 1772...

Will start a bodge PCB for all this soon. There still shouldn't be any real reason for the DMA port to malfunction how it is now anyway... But known how iffy all this stuff is, I wouldn't be supprised...

Post by **Icky** » 14 Oct 2018 09:28

exxos wrote: 14 Oct 2018 02:56 Yeah I saw Atari drives have the buffers, again odd that ste have same buffers again... I guess it could explain a little why Atari drives seemed to work better than 3rd party ones back in the day. I guess most issues were with pre-ste machines as I assume 3rd party drives may not have the buffers and could fail to function correctly.

Mostly thoughts are for ultrasatan. Jookie used resistor dividers on the io, so suspect a fair load on the io lines, so buffers would help there. But I don't know how later ones were done.. If they use resistors still or proper level translation chips..

I will probably add DMA buffers just to be sure anyway. Taking load away from the DMA can only be a good thing. And of course buffer to isolate 1772...

Will start a bodge PCB for all this soon. There still shouldn't be any real reason for the DMA port to malfunction how it is now anyway... But known how iffy all this stuff is, I wouldn't be supprised...

I also like the idea of buffer on the DMA port and to isolate the 1772. This should help protect the chips as mentioned by rpineau.

Post by **Icky** » 14 Oct 2018 09:32

OK - One more to add to the testing pot.

We have MIDI.

Using Pro24 on the STF Remake to play a simple song (pretty rubbish one at that - probably not the right instrument setup) out of MIDI to my MIDI controller hooked up to GarageBand.

Post by **exxos** » 14 Oct 2018 11:40

:bravo:

Did you test the nasty dma ? Not sure if I missed that post or not.

Post by **Icky** » 14 Oct 2018 11:56

exxos wrote: 14 Oct 2018 11:40 :bravo:

Did you test the nasty dma ? Not sure if I missed that post or not.

No not yet - Juggling a few things around between my DIY jobs I have to do this weekend. Tiling a bathroom or Atari work - hmm

Have just put it into the original but am trying to find all the parts I had stored to bring it up as it was hanging on my wall as art https://www.exxosforum.co.uk/forum/viewt ... f=18&t=700

Will definitely get this test done today

Post by **exxos** » 14 Oct 2018 11:58

Icky wrote: 14 Oct 2018 11:56 No not yet - Juggling a few things around between my DIY jobs I have to do this weekend. Tiling a bathroom or Atari work - hmm

Atari work helps humanity, tiling the bathroom just looks pretty :P

Icky wrote: 14 Oct 2018 11:56 Have just put it into the original but am trying to find all the parts I had stored to bring it up as it was hanging on my wall as art https://www.exxosforum.co.uk/forum/viewt ... f=18&t=700

Yikes! Yeah I remember seeing that before now!

Icky wrote: 14 Oct 2018 11:56 Will definitely get this test done today

:thumbup: My sanity is hanging by a thread with this if that helps :crazy:

Post by **Icky** » 14 Oct 2018 20:18

exxos wrote: 14 Oct 2018 11:58
Icky wrote: 14 Oct 2018 11:56 No not yet - Juggling a few things around between my DIY jobs I have to do this weekend. Tiling a bathroom or Atari work - hmm
Atari work helps humanity, tiling the bathroom just looks pretty :P

Icky wrote: 14 Oct 2018 11:56 Have just put it into the original but am trying to find all the parts I had stored to bring it up as it was hanging on my wall as art https://www.exxosforum.co.uk/forum/viewt ... f=18&t=700
Yikes! Yeah I remember seeing that before now!

Icky wrote: 14 Oct 2018 11:56 Will definitely get this test done today
:thumbup: My sanity is hanging by a thread with this if that helps :crazy:

Finally got the NASTY DMA in an original ST.

Well floppy boots but the HDD is not recognised.

Post by **exxos** » 14 Oct 2018 21:46

Icky wrote: 14 Oct 2018 20:18 Well floppy boots but the HDD is not recognised.

So nasty DMA is faulty then.. along with the old 1772 ? I guess its possible the RD line could have damaged the 1772 and DMA...

Post by **Icky** » 14 Oct 2018 22:04

exxos wrote: 14 Oct 2018 21:46
Icky wrote: 14 Oct 2018 20:18 Well floppy boots but the HDD is not recognised.
So nasty DMA is faulty then.. along with the old 1772 ? I guess its possible the RD line could have damaged the 1772 and DMA...

Looks that way. Now I need to find me a new DMA chip now

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