exxos's Atari, Amiga & retro forum

Fast ram has nothing to do with st ram. So you can have the normal 4mb st ram plus 8mb fast ram.

exxos wrote: 25 Nov 2018 02:07 Fast ram has nothing to do with st ram. So you can have the normal 4mb st ram plus 8mb fast ram.

Ok that's what I thought. I'd better decide how I'm upgrading it to 4mb then.

Have my mega 4 setting here just waiting for it. Just pop the 1.5 out and were ready. :excited: :excited: :excited:

I will try and find some time this week to build up one for testing.. i need to finish up the STE boosters as can only work on one machine at a time :)

The firmware *should* be compatible with the previous V2.2 booster...

I've plugged in my SEC booster to help TF with his floppy write problem, which I seem to have as well :roll:


Long story short, seems there needs to be a delay on CPU_DTACK after a DMA cycle. So I run ST_BGACK though a FF clocked on 8MHz to buffer/delay the signal and add it to my CPU_DTACK delay logic. So normal RAM access works same speed as before, but CPU is stalled with DTACK a extra 8MHz cycle after a DMA cycle..



The problem is, I get this at the start of each format..


Formatting a floppy works fine now though (was just resetting after a couple of track formats). Not really sure if that error is a booster error or a "bug" in TOS due to the faster (50MHz) CPU ?

I will add on the pull ups onto the DMA just to see if that has anything to do with it also...

So the pull up fixes on the DMA & 1772 didn't help..

But when the drive motor is off, and I click OK to format, I get that error.. if I wait for the motor to turn off, I can repeat the error every time.. if I click retry while the motor is on, it works fine.

Even more odd, it works fine with a original 720K drive.. hmm..... :stars:

Oddly the format fails towards the end with my 720K drive (bad floppy probably) and I get that error and can't get any further by clicking RETRY.. I guess because the motor is now off.. very odd....

EDIT:
The 720K failing format and the error happens with the stock 68000, so must be a TOS issue...
The diagnostic cart reports no floppy issues..

I will try FCOPYIII....Seems to work ok as well..

Don't know if it's related but on the doubleST I've had, several times, that "everything" seemed to work ok except floppy. So far it's been fixed by "luck" just shifting the clocks about a bit - which if I've understood your comments before mostly means I've skewed DTACK.

troed wrote: 04 Jan 2019 08:39 Don't know if it's related but on the doubleST I've had, several times, that "everything" seemed to work ok except floppy. So far it's been fixed by "luck" just shifting the clocks about a bit - which if I've understood your comments before mostly means I've skewed DTACK.

I never thought about it with the floppy acting up... Can you format a floppy OK on it now then or does that act up still?

For me its odd, but seems more like a TOS problem as only gem format seems to be malfunctioning..

I seem to have solved this odd error issue now..


Oddly the 720K drive which was working, wasn't working this morning. One of those red-herrings which throw you off!

So I have delayed ST_AS by another CPU clock cycle.. So now I have..

Before I was only using AS1 for the ST_AS.D input, now its AS2 and the issue seems to be resolved 8-)

Crappy cam video .. ( I can't hold the cam and use keys to move the mouse at the same time!)

What's been annoying me is I have no output to decode ROM.. Now I have the new dualtos boards with TOS104/206, its bodge wire time on the SEC's PLD...