exxos's Atari, Amiga & retro forum

Hi all,

Has anyone experienced this before?

* If booting the STe with no floppy drive connected: straight to desktop.
* With floppy connected (with disk inside): Floppy accesses and reads before TOS loads (white screen) and freezes on white screen forever.
* With floppy connected (no disk): Floppy accesses, white screen for 20 seconds, then TOS. If I put a disk in and access it, machine freezes (locks-up)
* Running diagnostic cart: When doing 'DMA test' it freezes on the blue screen, completely locks. On a healthy machine it will go to a red error screen due to missing test equipment on the port.

So far I've just swapped the DMA chip, still same issue. I haven't done any mods to this board except replacing the reset capacitors. Also using a known good floppy drive. Before I go down the 'rabbit hole' of things I *could* do, what would be the logical first few things to do?

Of course, this is with a good re-capped psu.

I should also mention the machine's blitter is missing from its socket. Not sure if that would effect DMA or not.

Steve wrote: 01 Dec 2021 22:35 I should also mention the machine's blitter is missing from its socket. Not sure if that would effect DMA or not.

Most probably not helping matters.

Ok, found a blitter and put it in... floppy works now lol :D

STe's are weird :)

Steve wrote: 02 Dec 2021 11:03 Ok, found a blitter and put it in... floppy works now lol :D

STe's are weird :)

Didnt want to say, as I couldnt remeber 100%, but I was thinking TOS 1.06/2.06 uses blitter to draw desktop. Maybe refreshing the drive A box was doing it? :shrug: (Maybe one of the OS coders here can clarify).

Is it because you have an MCU with no internal blitter ? I guess that you had the proper jumpers when the external blitter was not installed ?

sporniket wrote: 02 Dec 2021 11:12 Is it because you have an MCU with no internal blitter ? I guess that you had the proper jumpers when the external blitter was not installed ?

I don't see any jumpers, are there some? Of course the mcu has no internal blitter, it has an external blitter :)

Bus control signals are routed via the blitter. When you unplug the blitter the cpu can't do deal with DMA cycles. This is why you have to solder jumpers on the STFM / MEGA ST to reconnect the signals when the blitter is missing.

exxos wrote: 02 Dec 2021 11:16 Bus control signals are routed via the blitter. When you unplug the blitter the cpu can't do deal with DMA cycles. This is why you have to solder jumpers on the STFM / MEGA ST to reconnect the signals when the blitter is missing.

I might be sounding like a dick but if you knew that why didn't you tell me in the first place?

Steve wrote: 02 Dec 2021 11:20 I might be sounding like a dick but if you knew that why didn't you tell me in the first place?

I did say its likely not helping matters. But if I spoonfeed answers right at the start then nobody learns anything. So I gave a very big hint...