exxos's Atari, Amiga & retro forum

exxos wrote: 05 Mar 2021 16:53 I assume you have the 3 sets of jumpers set correctly also ?

JP18 and JP19 linked (720 mode)
JP22: 2&3 (8MHz 1772)

Are those the ones you are referring to?

kodak80 wrote: 05 Mar 2021 21:06 I need to get back to testing the 1.44mb GAL but my initial testing with the SJ3 soldered did not work and only 720k disk images on my Gotek worked. Are your disk images 720k or 1.44mb?

Oh, interesting (that the GAL with SJ3 soldered did not work).

I'm using 720k images.

AndresPlazaR wrote: 05 Mar 2021 22:09 Oh, interesting (that the GAL with SJ3 soldered did not work).

I'm using 720k images.

720k disk images work fine for me regardless of what the GAL was set to do. Just could not get 1.44mb disks to read from my Gotek. I need to check that 16mhz feed from the shifter looks correct with my scope and do some further testing.

If 720k are not working for you then this may be a different issue as the normal system 8mhz clock should be driving the access for 720k disks so might be worth checking this with your scope to confirm 8mhz clock to WD1772 pin 18 is correct. With JP22 pins 2 and 3 jumpered this should bypass the clock from the GAL. If JP22 pins 1 and 2 are jumpered will feed the clock from the GAL to the WD1772 IC.

I would recommend testing with JP22 pins 2 and 3 jumpered and JP18 and JP19 are also jumpered before you start running and testing that the GAL.

exxos wrote: 05 Mar 2021 16:39 You may have to scope the 16Mhz line to see how it looks on pin 1 of the GAL...

Pin 1 in the GAL measures 16MHz +/- 0.12 : Pin 18 in the 1772 (@kodak80 ) measures 8MHz +/- 0.13 :

AndresPlazaR wrote: 05 Mar 2021 22:30 Pin 1 in the GAL measures 16MHz +/- 0.12

What clock do you get on GAL pin 14 which is clock output from GAL to WD1772?

With JP18 and JP19 shorted, I believe GAL should generate standard 8mhz clock on pin 14.

JP19 on the H5 schematic may not be correct if as the label on this should be HD1_SEL but it showing in the released H5A schematics as N$57. This may mean that the GAL pin 4 is not connected to JP19 and impact GAL functionality?

AndresPlazaR wrote: 05 Mar 2021 22:30
Pin 1 in the GAL measures 16MHz +/- 0.12 :

Pin 18 in the 1772 (@kodak80 ) measures 8MHz +/- 0.13 :

These look normal clocks.

kodak80 wrote: 05 Mar 2021 22:38 What clock do you get on GAL pin 14 which is clock output from GAL to WD1772?

With JP18 and JP19 shorted, I believe GAL should generate standard 8mhz clock on pin 14.

There is no clock on GAL pin 14, only 5v. :-(

AndresPlazaR wrote: 05 Mar 2021 23:02 There is no clock on GAL pin 14, only 5v. :-(

Did you program the GAL yourself ? Either its not programmed correctly, or faulty GAL by the sounds of it.

kodak80 wrote: 05 Mar 2021 22:46 JP19 on the H5 schematic may not be correct if as the label on this should be HD1_SEL but it showing in the released H5A schematics as N$57. This may mean that the GAL pin 4 is not connected to JP19 and impact GAL functionality?

H5A 1.44 schematic.png

Good spot!

It is connected to the GAL.. the label is just wrong.. feking Eagle...