16BIT ROM CART THOUGHTS

[exxos]

So DIAG_LO_HI.bin is a merge of the 2 other one and then byte-swapped ready to program as it starts with $52 $FA $5F $23 (diag cartridge starts with $FA52235F).
So this file looks good to me and is ready to program.

Thanks... I will try a new rom when they arrive as mine eproms are iffy at best of times.. but I think this can't work for some reason :shrug:

[rpineau]

I think the Eprom will be fine but may be the logic on the board could be the issue. There is no reason a 16bit eprom would not work.

[exxos]

New ROM still not working :(

Here is the schematic in case I did something stupid... Though I did wire A15 which isn't actually used on the diag-cart.. It could be HI and selecting the wrong ROM location..

cart.png

EDIT:
Yep A15 seems to be high :roll: So I have cut the track and hardwired to 0V and still no boot :( :shrug:

[rpineau]

And S1, S2 and S3 are grounded in your test ?
Also you could wire /OE to ground and rely on ROM4 to select the chip.
Have you try checking what's going on when ROM4 goes LOW on /UDS, /LDS, /CE and /OE ?
Also for 128K cartridge, A15 is wired but /CE need to go low for both ROM4 and ROM3, so similar to your UDS/LDS with the diodes
So if the diag cartridge code jumps to somewhere above 64K you run into the same code instead of where you need to go and it probably crashes.
ROM4 selects $FA0000 through $FAFFFF (64K)
ROM3 selects $FB0000 through $FBFFFF 64K)

Rodolphe

[exxos]

And S1, S2 and S3 are grounded in your test ?
Also you could wire /OE to ground and rely on ROM4 to select the chip.
Have you try checking what's going on when ROM4 goes LOW on /UDS, /LDS, /CE and /OE ?

All switches are gnd yes...
/OE is 0.76V (drop over diode)..
/CE is high :shrug: I only check with meter (not scope)

[rpineau]

I updated my post with more info.
I found plenty of places where A15 is connected , as well as ROM4 and ROM3 , for 128K cartridge

[exxos]

I updated my post with more info.
I found plenty of places where A15 is connected , as well as ROM4 and ROM3 , for 128K cartridge

Looking at the proper diag-cart, ROM4 is jumpered, ROM 3 isn't.. so for that cart ROM3 does not seem to be used.

There also jumpers for 64K/128K which is open... 256K is jumpered.. so need to check where that line is going..OK A13..

EDIT:
OK I think something is wrong with the edge connector.. on the proper cart ROM 4 is going 4 pins up from the bottom on top layer.. but on my cart top layer 4 pins up is A2 :roll: So I think the connector has layer order wrong :(

Its correct that 2 pin use gnd on the bottom end of the connector, but on mine its on the top layer, and should be bottom layer.. so its not wrong order of pins , just on wrong layer... but I dont get how this problem not show on the RTC boards :shrug:

[rpineau]

So my connector is al wrong ?
I believe I followed this : http://info-coach.fr/atari/hardware/int ... _cartridge

I remember you making changes and sending it back to me .. did the 2 layer got swapped ?!
Rodolphe

[rpineau]

Ok, loaded the lib in eagle, hide top layer, clock on first bottom layer left pin ... it says PIN 39 !!!!
39 should be on the top, 40 on the bottom !!

[exxos]

So my connector is al wrong ?
I believe I followed this : http://info-coach.fr/atari/hardware/int ... _cartridge

pinout is correct I think on site, and your pinout follows that... but on the actual PCB part the layer order is wrong...

Site has pin 38 & pin 40 as GND.. and your schematic shows that...

11.jpg

But on actual PCB..

22.jpg

2 GND lines on the top layer 38&40 (should be bottom like on the site)

So no idea whats going on ? :shrug: