Icky - Progress

[Icky]

Is there a typo on pin 5, as on the ST sch pin 5 is drive_0..


1.JPG

Yes a typo in my diagram pin 5 should be drive 0 - I did create it in the early hours - thought I had found all the bugs.

I guess I'm not so good with connectors either

[Icky]

Is there a typo on pin 5, as on the ST sch pin 5 is drive_0..

Yes a typo in my diagram pin 5 should be drive 0 - I did create it in the early hours - thought I had found all the bugs.

I guess I'm not so good with connectors either


Correcting -

Screen Shot 2018-10-08 at 13.21.15.png (232.12 KiB) Viewed 3721 times

[exxos]

I guess I'm not so good with connectors either

12 pins better than me though

Started a new thread for this board...

https://www.exxosforum.co.uk/forum/viewt ... =19&t=1248

[exxos]

Just looking through the DMA pdf...

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It only seems to say is driven with a open collector, but does not really say is needed for any reason..

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[Icky]

Just looking through the DMA pdf...

It only seems to say is driven with a open collector, but does not really say is needed for any reason..

I was just scoping the RDY line on the DMA and noticed the undershoot like in your BAD DMA MYTH http://www.exxosforum.co.uk/atari/last/DMAfix/.

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[exxos]

I was just scoping the RDY line on the DMA and noticed the undershoot like in your BAD DMA MYTH http://www.exxosforum.co.uk/atari/last/DMAfix/.

It can also be where you have grounded the scope.. assuming you are on a gnd point very close to the DMA..

Also try on x10 probe... Sometimes a probe itself can appear to give you things which are not actually there...

It is also worth probing every pin of the DMA to see if anything looks odd... The address and databus to the DMA will likely look like chaos anyway..

[Icky]

I was just scoping the RDY line on the DMA and noticed the undershoot like in your BAD DMA MYTH http://www.exxosforum.co.uk/atari/last/DMAfix/.

It can also be where you have grounded the scope.. assuming you are on a gnd point very close to the DMA..

Also try on x10 probe... Sometimes a probe itself can appear to give you things which are not actually there...

It is also worth probing every pin of the DMA to see if anything looks odd... The address and databus to the DMA will likely look like chaos anyway..

Probe is on 10x and ground point I am currently using is the DMA socket shield lugs. Will move it closer and look at the other lines.

[Icky]

It can also be where you have grounded the scope.. assuming you are on a gnd point very close to the DMA..

Also try on x10 probe... Sometimes a probe itself can appear to give you things which are not actually there...

It is also worth probing every pin of the DMA to see if anything looks odd... The address and databus to the DMA will likely look like chaos anyway..

Probe is on 10x and ground point I am currently using is the DMA socket shield lugs. Will move it closer and look at the other lines.

So far nothing looks out of place. Have even tried different ACSI cables and drives.

Odd though as I did get the device recognised once but not since - must of been a fluke or all the stars aligned

[exxos]

Odd though as I did get the device recognised once but not since - must of been a fluke or all the stars aligned

Have you tried with and without the RP900 in place ?

Other than that TTL chip there isn't much else to check... for the hell of it, if you have a 001 DMA

It could be possible noise on the DMA port itself on a dataline ?

[Icky]

Have you tried with and without the RP900 in place ?

Just did - no difference still doesn't see floppy when hdd is connected

Other than that TTL chip there isn't much else to check... for the hell of it, if you have a 001 DMA

Nope don't have a -001 DMA just -38's