exxos's Atari, Amiga & retro forum

Forgottenmyname wrote: 23 Sep 2018 19:32 Please could you show me the pinout you used?

It might be incompatible with my FTDI guess, so can try a usb-serial later on.

This is what I ended up with. My USB to Serial has a male 25 pin and the STF has a male 25 pin. Therefore I wired two female 25 pin sockets together like this - hope this helps:

Ok, thanks Icky, I only connected Rx,TX and Gnd, will try the rest too but with a not so bodged cable.

rpineau wrote: 23 Sep 2018 19:15 so I6 (IPL 6) is the MFP. "No (I6) error" ..looks like MFP interrupt handler are ok.

Thanks rpineau

One more step closer :)

With serial working, all we now need is the DiagROM which should arrive from Exxos tomorrow - fingers crossed.

So, as suspected, a NULL modem cable.

stephen_usher wrote: 23 Sep 2018 19:56 So, as suspected, a NULL modem cable.

Indeed - one and the same :)

rpineau wrote: 23 Sep 2018 19:15 so I6 (IPL 6) is the MFP. "No (I6) error" ..looks like MFP interrupt handler are ok.

I6 is simply the 6th test during initialization. It has nothing to do with IPL6 or the MFP interrupts! In fact, this step simply tests that a write to $0 causes a bus error. After that, the diagnostic cartridge will enable interrupts and will go on printing "Testing MFP, Glue timing, Video". When it shows "E7 Spurious interrupt" instead, this means that an interrupt was signaled to the CPU but no device responded to the interrupt acknowledge. I suppose this could happen when at least on the IPL lines to the CPU is stuck low.

Ok, my mistake :)
:hide:

Spurious Interrupt either means something on the bus is corrupting the data on the bus and running the wrong interrupt (my thoughts for the ACIA as I have had that issue with my boosters), or the interrupt vector hasn't been set in RAM. I don't know much about how all that stuff works though. I think the fault was autovector issues, but can't remember if the cart said auto vector or not. I did know more about this stuff while doing the SEC code, but mostly forgot how it all works now :(

I6 should never get triggered. With my SEC booster, the ACIA cycles were causing issues corrupting the bus and ended in I6 errors. So for some reason we are running I6 when we shouldn't be.. The corrupt data on screen hints to corruption somewhere..

We ruled out the ACIA conflicts at least. It shard to know where or what to look for, though could be something relating to the MFP circuit.

exxos wrote: 23 Sep 2018 22:08 We ruled out the ACIA conflicts at least. It shard to know where or what to look for, though could be something relating to the MFP circuit.

Code: Select all

Exception Vectors
$060  Spurious interrupt (level 6)
$078  Interrupt level 6 (MFP interrupts)

I took your suggestions and started looking at the MFP on an original STFM. I noticed a few pull-ups missing especially the IRQ pin 32 on the MFP.

I did that pull-up with a 1K as I wanted to see if this was part of the problem and .......

We have a green desktop - although still with the glitches

:bravo:

I will check the pull ups tomorrow again. I didn't see I missed any but obviously you are on the right track there!

I don't get the odd graphics problems though. Its like the shifter is getting bad data for some reason. It must be pretty good on ram access to even get to the desktop though..odd.