exxos's Atari, Amiga & retro forum

Icky wrote: ↑Sun Sep 16, 2018 9:42 am
I don't have the floppy connected at the moment.

But here is video of first boot. As you can see I get the black screen then it starts to go out of sync.

Looking at the video its not booting tos yet. One of the first things I think tos does is to set the screen white.

You say the CPU is switching /as .. If its doing that all the time then its stuck in a loop trying to do something... This is where terrible fires new toy would be really useful to debug..

Is berr switching ? What about dtack?

exxos wrote: ↑Sun Sep 16, 2018 9:48 am You say the CPU is switching /as .. If its doing that all the time then its stuck in a loop trying to do something... This is where terrible fires new toy would be really useful to debug..

Is berr switching ? What about dtack?

It was Forgottenmyname that mentioned the /AS.

I got the output last night so did not have a chance to start looking at the signals as well. That is the plan for today if I get the time.

Would like to see if Forgotenmyname can get video out on his as well today to see if his board is behaving the same.

That's my first task today on the board when I get time. I think my problem may be that I'm not using a real scart tv, so will get the old 14" portable tv out later.

I was also thinking of soldering on the serial port to see if I get an output from there with a diag cart.

If it's of immediate benefit I can solder in the floppy wires?

What should I see on berr and dtack ideally?

If you get BERR going low, then something on the bus hasn't responded and the GLUE resets the CPU normally.

/DTACK should always follow within a few cycles of /AS going low.

Diag-cart won't work unless TOS is partly running.. Diag-rom is the toy for that, but it needs the serial port working, and we don't know if thats working yet anyway..

I would also check the ROM_CE line on the ROM IC, then we know if GLUE is decoding ROM address or not. It will likely only pulse low once after reset.. so could be tricky to capture.

Ok cool, will let you know later.

First reply of the night. So I do have an output via scart to my old tv. It's a rapidly rolling red screen with black border. My scart cable is a bit dicky too, so will need to fix that later.

Not sure if it's of any use but the keyboard light only comes on whilst holding down reset.

Will get the scope set up again shortly.

Forgottenmyname wrote: ↑Sun Sep 16, 2018 5:02 pm First reply of the night. So I do have an output via scart to my old tv. It's a rapidly rolling red screen with black border.

Check H&V sync coming out of GLUE and check it on the monitor port..

Forgottenmyname wrote: ↑Sun Sep 16, 2018 5:02 pm Not sure if it's of any use but the keyboard light only comes on whilst holding down reset.

Did you plug the keyboard right in without any other mods ? Sounds like a gnd is missing, I guess you may have to wire pin 1&8 together on the KB plug itself just to rule that out.

I haven't connected pin 1 and 8 yet on the keyboard but will do that shortly, just wanted to make sure it was definately required.

Will check the glue signals as well.

Forgottenmyname wrote: ↑Sun Sep 16, 2018 5:02 pm First reply of the night. So I do have an output via scart to my old tv. It's a rapidly rolling red screen with black border. My scart cable is a bit dicky too, so will need to fix that later.

Glad to hear you now have a video signal. This is all exciting times. Am really enjoying building and now starting to hunt down getting this working.

Qudos to Exxos getting a board in a shape that it gives a signal of sorts on first turn on. Let’s hope we don’t have many problems to solve to get it running correctly.

I haven’t had time today to look at the board. Leaking shower has taken up my day.

I am hoping I will have a few hours later tonight to take a closer look.

Just got home and looking at Hsync I have it inverted... On the original ST diagram it goes though a inverter to a LS74.. on the STF the inverter isn't even there ... So I think Hsync is actually wrong and its inverted when it shouldn't be .. I will do some more checking...


EDIT:

hmm....
Its actually got HSYNC and /HSYNC and HSYNC2 ...

HSYNC2 MODULATOR is double inverted to modulator.... (not used)

HSYNC goes to the monitor connector it seems (so I have it inverted it seems)..

/HSYNC goes to the LS74 on modulator systems... (not used)