Atari STE writing to floppy and hard disk problems

[mst]

My STE machines behaves rarely writing floppies; not always, only sometimes;

but recently I acquire a hard disk device and this is completely annoying; rarely I can write (from desktop, I do not test any software that write to disk)
2 or 3 files, without corrupting the entire FAT table on the disk. As an example: After write a file you can view an infinite chain of folders, that contain the same labeled folders... each one containing a 960 MB file... from an external point of view can produce laugh, but from the user point of view

Initially I think on bad RAM modules,

My Atari 1040 STE has 4 MB of RAM, and suffered the same as entry 11 July of 2016:
https://www.exxosforum.co.uk/atari/last/DMAfix/index.htm

First, I tested the RAM using the software YARRT.TOS, but after 32 passes, the RAM exhibits zero errors.

Due to this, the research started... and I found the Exxos research about DMA problem,

My computer appears to be manufactured on 1990, and the DMA IC chip is the: C398739-001A , followed by: c ATARI 1990 and: -31 160511-01
the only difference on the numbers are the top ones, probably the day, month and week of chip manufacturing.

Reading the Exxos research, I replaced the CPU, a MC68000FN8 with a MC68HC000FN20 I have on the shelf, a never used one from past projects.
But the problem remains...

At this point, I need to ask for external help... what are the next steps? Further recommendations?

Thanks in advance,

[exxos]

You need to do the mandatory fixes. https://www.exxosforum.co.uk/forum/viewt ... =17&t=1585

[rubber_jonnie]

Agree with @exxos , you need to replace the data bus pull ups and add pull ups to the WD1772 data lines as per the mandatory fixes link he sent.

[mst]

You need to do the mandatory fixes. https://www.exxosforum.co.uk/forum/viewt ... =17&t=1585

Thanks!

Also the 10K pull-up on the WD1772 controller is not hard to accomplish!

I am curious about one thing,
Could be this fix apply on the external hard disk data lines?

[exxos]

Could be this fix apply on the external hard disk data lines?

I doubt it would do anything.. on the STE they are driven by buffer chips.. if anything , hard drives should have them internally if needed, but mostly for STFM type machines..

[mst]

Agree with @exxos , you need to replace the data bus pull ups and add pull ups to the WD1772 data lines as per the mandatory fixes link he sent.

Thanks Rubber_jonni;

If I understand well, I need to do:

3) STE ,STFM,MEGA ST, (likely other machines effected) DMA Pull up on databus needed.

and

12) ST/F/M/E /MEGA ST- Bus resistors

The 5) STE - Change the CPU for HC type to fix DMA issues is already done;

Currently I am performing the recommendation 3)

I ´ll report asap,

[rubber_jonnie]

Yep that's it.

[exxos]

I think this will be a interesting case as this is using a supposed "good DMA chip". Problem is, if the fixes don't solve it, you pretty much have to replace the motherboard or spend endless time trying to track down the faults.. which is why we did a new motherboard..

In this case it could well be bad buffers or alike, mostly its just quicker & easier just to change the chips than trying to diagnose if things may or may not be faulty.

[mst]

I think this will be a interesting case as this is using a supposed "good DMA chip". Problem is, if the fixes don't solve it, you pretty much have to replace the motherboard or spend endless time trying to track down the faults.. which is why we did a new motherboard..

In this case it could well be bad buffers or alike, mostly its just quicker & easier just to change the chips than trying to diagnose if things may or may not be faulty.

Yes, my STE appears to be more a prototype one than a final commercial version. TOS version is 1.06
I upload a photo of my mobo; its not a high quality one, but my mobo has airwires without shielding!, that obviously is a crime on a 8 MHz 5 volts digital based system.

Currently

3) STE ,STFM,MEGA ST, (likely other machines effected) DMA Pull up on databus needed.

and

5) STE - Change the CPU for HC type to fix DMA issues are applied (New one is Motorola brand, MC68HC000FN20 )

Floppy appears to operate ok, but hard disk writing is almost impossible; and sometimes (about 15%) of times I encounter some hard disk reading problems, when continuosly loading huge amounts of data; I am testing using the Metal Slug port demo, that takes 3,39 MB of data loading. Readout problems are easily detected, due to the sprites used in this port contain machine code; if any sprite is bad loaded, when you tries to use it, it behaves strangely or it causes a crash on the system, many bombs.

Apply 12) ST/F/M/E /MEGA ST- Bus resistors is not as quick as 3) . I do not want to remove original resistance ladders, I would prefer to place the new ones on a parallel way.

5 volts and 12 volts from PSU are pretty good, using oscilloscope, while STE is running Turrican 2, the voltage are stable, with some minor 100 mV spikes up and down. The system was in a store from 1990 and opened as first time on 2014 (when I bought it, and use it as first time).

Talking about the new mobo, I have no idea about it... also many of the components, are no socketed, these are soldered directly to the mobo, and some of them are extremely complex to remove If you can talk about the new motherboard... thanks


Images are reduced only to 1100 pixels or similar, due to 800 pixels is a bit unreadable for some of them,

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SAM_3644.JPG (108.33 KiB) Viewed 3629 times

SAM_3643.JPG (100.04 KiB) Viewed 3629 times

[exxos]

So the bus resistors are not changed looking at your images ? P100 needs to be 1.2k, all 1772, DMA fixes need doing..

New mother is huge subject , current build for example is here https://www.exxosforum.co.uk/forum/viewt ... 100&t=3654