Falcon Diagnostic cart/accelerated bus

[Rustynutt]

Hi All,

Is there a member here with a Falcon setup with a bus speeder able to run the diagnostic cart?

Here, at 20mhz bus, diagnostics reports a keyboard error.
The KB ACIA is being feed a 500khz clock from an independent oscillator.
Diagnostic version is 1.27b.

Desktop boot and function is normal.

Chris, are you familiar with what the cart is looking at when it checks the KB?
Is your diagnostic cart modified Atari, or original code burned into your ROMS cart?

Finally, post #1

[exxos]

Nothing is modified ...

You can't feed the acia on its own clock can you ? Its normally generated from the CPU and its a enable signal not a clock. No idea how its generated on the falcon. Have you tried just putting the acia back to stock ?

[Rustynutt]

A Muppet wrote:
Every falcon bus speeder is Generating a 500khz clock to get the acias working. Otherwise the baud rate will be higher and the keyboard clock has to be changed too.

Yes, normally the COMBEL feeds the ACIA the 500khz clock.
When a speeder (Nemesis, Phantom) is installed, the over clock causes the COMBEL to increase the ASCI clock to fast. Those accelerators provide an independent 500khz clock. A pin is lifted from the ACIA (mine is socketed), and clock wire from the speeder is attached.

It's been over 20 years since installing the Nemisis, and forgot if then had issues with the diagnostic cart with a faster bus. The cart comes up, but the keyboard isn't working, making me think it's looking at some other indicator.

[Rustynutt]

Every falcon bus speeder is Generating a 500khz clock to get the acias working. Otherwise the baud rate will be higher and the keyboard clock has to be changed too.

Now there's a thought.
Can the kb clock be changed to work with the faster ACIA clock?
Might not be practical though if using 2 different clocks as the Nemesis does.
For a fixed speed, be a much cleaner solution.

[exxos]

I don't see the problem in running the acia faster anyway.. I run them 4x speed on my sec booster just fine. The 68B50 is rated for 2mhz!

[Steve]

The premise of the question doesn't make any sense. The diagnostic cart runs before TOS, boosters are only enabled when loading an enabler program in AUTO. So as far as I know, it is impossible to run the diagnostic cart while the falcon is boosted.

[Rustynutt]

Im really sorry this question has been so misunderstood.
The first, am just asking if there is a Falcon user, which has a bus speeder installed, can test it using a diagnostic cart.
Anyone who does will completely understand the question.
That's all.

Yes, ACIA's, the ones I have can go 10mhz (I think). That's not the issue. For the Falcon KB to work, the COMBEL must supply the ACIA a 500khz clock, nothing more, nothing less. That, or a 500khz clock provided to the ACIA independently, as it is an asynchronous function.

This particular test, the main 32mhz oscillator has been replaced with 40mhz unit.

The bus is "accelerated" without autofolder programs.

The reason I'm asking, one, threw away my null modem cables years ago, if not, would simply use a separate terminal to operate the diagnostics.

But the primary reason is testing with various oscillators without booting TOS. The Blitter can make this problematic.

This isn't a repair, it's for bench testing.
The Falcon works fine.

[exxos]

I guess it depends what cart you're using ? Mine are always fitted with 55ns ROM's so can basically run double speed of normal carts. I run the ROM's at 32MHz on the STE. I don't think you're getting that fast anyway ? Though don't know how slow the falcon logic is with it all.

There is also a nagging issue of if the bus pullups need replacing on the falcon or not...

[Steve]

Im really sorry this question has been so misunderstood.
The first, am just asking if there is a Falcon user, which has a bus speeder installed, can test it using a diagnostic cart.
Anyone who does will completely understand the question.
That's all.

This particular test, the main 32mhz oscillator has been replaced with 40mhz unit.
The bus is "accelerated" without autofolder programs.

Yes I have a bus speeder in my Falcon, no I don't understand the premise of your question and no I am not an idiot. You may have replaced your oscillator with 40mhz, your machine may run accelerated without auto programs, but the nemesis and phantom do not.

nemesis/phantom do require the auto program enabler, and therefore cannot run a diagnostic cart while boosted.

So your machine is getting keyboard failure in diagnostics does in no way translate to a falcon fitted with nemesis/phantom diagnostic and therefore does not provide you with any useful comparison data.

[Rustynutt]

You read a pre edited post
Reviewing the FSM COMBEL pin out description for the 500khz clock, and 500khzW clock, the pin number are assigned the same. This is not the case. Removing the ACIA from its socket, lifting and tying pin 4 to 3 where the external 500khz clock is attached solved the boot issue using the cartridge port.
This is also somewhat explained in the Nemesis installation manual.
The machine will boot the cart with a 50mhz main clock with keyboard function.
All else is normal.
This allows me to test various changes to hardware, and at least have a limited set of diagnostic tools.

Next test will be with an Eagle Sonic installed to test 50mhz CPU/ 25mhz bus.
No software will be harmed, the 50mhz input to the Eagle Sonic will be directly feed. This is already known to work on this machine using software selection booting TOS, however never addressed the kb failure while using the diagnostic cart.

Then move onto reinstalling the AB040 and work towards stability at 50mhz, where I left off 20 years ago.

Thank you for your input, it was noted.