Help hacking and restoring AX-350II sakhr

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By ali6x944

Expert (126)

ali6x944's picture

15-02-2018, 17:06

I think I will get it from jameco:
https://www.jameco.com/z/41464-10-Major-Brands-64KX4-100NS-H...
This chip seems to be pin to pin compatible, and have the same page distribution 64k x 4...

By ali6x944

Expert (126)

ali6x944's picture

16-02-2018, 08:14

For the FDD can I use 1.44M drive?
And is their an msx compatible gotek drive?

By Alexey

Paragon (1538)

Alexey's picture

16-02-2018, 12:46

You can't use the 1.44mb floppy for MSX instantly. You need to convert it by switching it to 720kb mode and to enable READY signal on pin 34.

The factory-made GOTEK should be reflashed with HxC or (better and cheaper) with FlashFloppy firmware in order to be MSX compatible. The whole operation takes 5 minutes.

By maxis

Champion (511)

maxis's picture

16-02-2018, 17:11

ali6x944 wrote:

For the FDD can I use 1.44M drive?
And is their an msx compatible gotek drive?

What are your skills in soldering/HW debugging and what is your tool set? Do you have an oscilloscope, if yes then which one? This will help us in finding a better solution for you, which you can implement.

By ali6x944

Expert (126)

ali6x944's picture

18-02-2018, 08:51

Well I can solder decently enough to go without cold or cracked joints, I have an ever-aging TQ-77 goot soldering iron, a rigol DS1054Z hacked to 100MHz and all options, and good amount of logic gates 74 series mainly with a bunch of monolithic chips, an static ram and flash rom, also have a rom programmer.

By maxis

Champion (511)

maxis's picture

18-02-2018, 10:18

ali6x944 wrote:

Well I can solder decently enough to go without cold or cracked joints, I have an ever-aging TQ-77 goot soldering iron, a rigol DS1054Z hacked to 100MHz and all options, and good amount of logic gates 74 series mainly with a bunch of monolithic chips, an static ram and flash rom, also have a rom programmer.

Excellent, so then adapting the 1.44 floppy is not a problem for you at all. Drive has to be reconfigured to provide disk ready and disk change logic.
However, before changing anything, just hook up the standard 1.44 floppy, set DS0 instead of DS1 and give it a try. You have a good chance, that it will work straight ahead. If your motherboard architecture is similar to YIS805 then likely the floppy will work as is.

By ali6x944

Expert (126)

ali6x944's picture

18-02-2018, 12:09

Sorry, but what do you mean by DS0 an DS1?

By maxis

Champion (511)

maxis's picture

18-02-2018, 12:53

ali6x944 wrote:

Sorry, but what do you mean by DS0 an DS1?

Disk Select 1 to Disk Select 0. All the PC FDDs are ALWAYS pre-configured with jumpers to respond on DS1. MSX, however, uses the standard FDD assignment. I.e. you will need to remove the jumper from DS1 and put in on DS0 position before putting the FDD into Yamaha.

By Alexey

Paragon (1538)

Alexey's picture

18-02-2018, 13:54

And with DS0 you need a straight ribbon cable.

By ali6x944

Expert (126)

ali6x944's picture

03-03-2018, 14:16

Do any one know what is the propose of the star key on sakhr machines?
Also do you remember the problem I had with the video adapter, It is probably from the color packets in the composite video signal because when I switched it to Black and white my converter gave me a sharp crisp images, I think my adapter is not handling the color video correctly, see the comparison photos and video below:
https://drive.google.com/file/d/1h5v1LU4J3nwYZ0nV7qrW0HPydLG...
https://drive.google.com/file/d/1XBmhmdVskxnH2vruM7iZsrTjzOq...
https://drive.google.com/file/d/1ttb6ImzL-uqAa9V0aA28yPZIupX...

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