Hard-reset button

[Tschibo00]

Hi guys,

after completing the super video, basic switch and SIO2PC upgrade I now installed a hard-reset button (found the schematics on the net) to my 130XE. Here are the schematics:

 

 

But you already guessed it: It doesn't work :-(

The thing consists of a mono-flop (74LS123) which simply pulls up pin 8 of the MMU for about 2 seconds. Simultaneously the normal reset button is triggered.

As far as I understand it, the mono-flop shall ensure, that the memory is cleared. Is pin 8 of the MMU the right pin for this?

Or is it just a problem with that pesky 74LS123 which gives only about 3,4V, which shall be something like a High

 

I also played around with the RC values, resulting in almost anything from a total hang to a soft-reset.

 

Could you please help me?

Thank you!

Hopper/SquoQuo

aka

Christoph

Edited March 27, 2006 by Tschibo00

[MEtalGuy66]

Hi guys,

after completing the super video, basic switch and SIO2PC upgrade I now installed a hard-reset button (found the schematics on the net) to my 130XE. Here are the schematics:

 

 

But you already guessed it: It doesn't work :-(

The thing consists of a mono-flop (74LS123) which simply pulls up pin 8 of the MMU for about 2 seconds. Simultaneously the normal reset button is triggered.

As far as I understand it, the mono-flop shall ensure, that the memory is cleared. Is pin 8 of the MMU the right pin for this?

Or is it just a problem with that pesky 74LS123 which gives only about 3,4V, which shall be something like a High

 

I also played around with the RC values, resulting in almost anything from a total hang to a soft-reset.

 

Could you please help me?

Thank you!

Hopper/SquoQuo

aka

Christoph

 

 

Hmm. never heard of that mod. Ive done Bob Woolley's Frezer reset button many times. It uses a 74xx86 (XOR) to toggle the status of the cartridge present register. It causes a cold reset WITHOUT clearing the contents of your extended RAM. And it does work.

 

http://atrey.karlin.mff.cuni.cz/~pavel/atari/freezer.html

[classics]

Your mod is trying to trigger the software interlock and crash the OS, then reset.

 

This will only work if the OS VBI is enabled and running, you have BASIC disabled and no cartridge is inserted.

 

It could also damage an inserted cartridge, depending on how its wired. I havent actually seen this installed.

 

You are much better off just installing a normally closed pushbutton inline with the 5v+ power supply.

 

Steve

Edited March 27, 2006 by classics

[Bryan]

What about this idea:

 

A simple OS mod that responds to the actual reset NMI input on Antic (unused in the XL/XE) and performs a coldstart?

 

-Bry

[classics]

What about this idea:

 

A simple OS mod that responds to the actual reset NMI input on Antic (unused in the XL/XE) and performs a coldstart?

 

-Bry

 

True, but if your going to modify the OS you can just add a soft-boot provision, like holding down Select+Reset to cause a coldstart.

 

Steve

[Bryan]

What about this idea:

 

A simple OS mod that responds to the actual reset NMI input on Antic (unused in the XL/XE) and performs a coldstart?

 

-Bry

 

True, but if your going to modify the OS you can just add a soft-boot provision, like holding down Select+Reset to cause a coldstart.

 

Steve

 

Well....you're no fun!

[classics]

Well....you're no fun!

 

 

A hardware only reset would be fun to build. Something with a RAS interrupt that disrupts the first read of the magic ram values after /reset perhaps?

 

Steve

[Bryan]

A hardware only reset would be fun to build. Something with a RAS interrupt that disrupts the first read of the magic ram values after /reset perhaps?

 

Steve

 

You could probably do it with a GAL that latches itself when it "sees" the address check, and clears itself on reset.

 

-Bry

[Osbo]

I did a simple reset on my space 800XL, I had to connect a wire to one of the chips, to the switch from there to the ground, it worked ok, but I never got to do a complete cold reset...

 

I found the link

 

http://www.myatari.co.uk/issues/aug2002/usa.htm

 

I also been trying to do a switch to enable/disable the BASIC without holding option every time.

Edited March 28, 2006 by Osbo

[classics]

You could probably do it with a GAL that latches itself when it "sees" the address check, and clears itself on reset.

 

Yep, probably will fit in a 22v10.

 

Steve

[Bryan]

You could probably do it with a GAL that latches itself when it "sees" the address check, and clears itself on reset.

 

Yep, probably will fit in a 22v10.

 

Steve

 

You don't even have to decode the whole address. Just distinguish it from all previous ones.

 

-Bry

[Rybags]

You can do a hard-reset on a completely un-modded XL.

 

Just press reset a second time, you have to get the timing just right.

 

The OS clears all of page 3 during warmstart, which means that the magic numbers at $33D-F get cleared (temporarily).

 

Pressing RESET again in that small time period will cause a cold-start. Once you get the timing right you can get it to work better than 1 in 10 attempts.

[Tschibo00]

Thanx everybody so far!

What I will try this evening is Rybags suggestion. Because I already have a working mono-flop I could use this to re-trigger the reset button after a given delay.

Maybe this will work fine.

What keeps me from doing the Freezermod-Reset is that I have to unsolder a pin of the GTIA, but if the other idea doesn't work maybe I will try this...

[RodCastler]

My main objective is to get rid of the long 5-15 seconds wait when cycle powering the 65XE.

 

For that, I'm ready to give Bob Woolley's THE FREEZER a try (http://www.atariarchives.org/cfn/12/02/0097.php).

I find his design quite elegant and simple: an XOR to trigger a hard reset via GTIA without resetting the MMU.

 

Now this brings some questions:

 

1) Why does pulling up pin 11 on the GTIA produce a cold reset? It seems like the original intention for pin 11 was to read the 4th joystick button, which is absent in XL and XE machines.

2) If the CPU goes into a frozen state I can power cycle several times and I will get garbage or blue screens all the time unless I wait 15 seconds and then power up. Will THE FREEZER force a hard reset on this scenario as well?

3) I don't really care to keep the contents of the memory, I just want a cold reset that saves me the waiting: Will a simple switch between 5V and Pin 11 on GTIA do the job of forcing a hard-reset without the need to isolate the GTIA pin from the motherboard?

 

Thanks!

[Rybags]

GTIA pins - since XL only has 2 ports the TRIG3/4 functions were reassigned, cartridge sense and keyboard sense for XEGS.

 

CPU frozen/crashed - freezer mod should still work, pressing Reset will always unlock the CPU regardless.

 

Memory contents - only the lowest 40 or 48K gets cleared by the OS. Forcing 5V onto the pin will only work if there's no cartridge present since the mod is designed to toggle that status. Simply changing the state to a set value will only be sufficient if that value is opposite to what it already was.

 

Also note - there's 2 different behaviours of the XL OS. Earlier version usually installed in 600XL will instantly coldstart if the cart state changes. Later version will simply lock up the machine then coldstart if you press Reset and the cart state is still different.

Edited June 26, 2014 by Rybags

[+JAC!]

An alternative to power cycling to also to use a Turbo Freezer or module port cartridges like The!Cart. They give you directy access to a programatic cold start without powering the machine on/off at all. That's faster and less pain for the machine, too. Also no modification required.

Edited June 26, 2014 by JAC!

[+bob1200xl]

The FREEZER does not pull pin 11 of the GTIA up or down - it reverses the current state of RD5, the signal that normally goes to pin 11. This will force a cold start when you press RESET because the OS thinks you pulled or inserted a cart while it was active.

 

RD5 will be connected directly to +5v if a cartridge is inserted. Don't try to pull pin 11 low.

 

Bob

 

 

 

 

My main objective is to get rid of the long 5-15 seconds wait when cycle powering the 65XE.

For that, I'm ready to give Bob Woolley's THE FREEZER a try (http://www.atariarchives.org/cfn/12/02/0097.php).
I find his design quite elegant and simple: an XOR to trigger a hard reset via GTIA without resetting the MMU.

Now this brings some questions:

1) Why does pulling up pin 11 on the GTIA produce a cold reset? It seems like the original intention for pin 11 was to read the 4th joystick button, which is absent in XL and XE machines.
2) If the CPU goes into a frozen state I can power cycle several times and I will get garbage or blue screens all the time unless I wait 15 seconds and then power up. Will THE FREEZER force a hard reset on this scenario as well?
3) I don't really care to keep the contents of the memory, I just want a cold reset that saves me the waiting: Will a simple switch between 5V and Pin 11 on GTIA do the job of forcing a hard-reset without the need to isolate the GTIA pin from the motherboard?

Thanks!

[Bryan]

Simple coldstart idea:

 

A switch that exchanges 2 RAM address or data lines. Flip the switch and RAM looks like garbage (but is not disabled), forcing a coldstart.

[+bob1200xl]

That might be dangerous... You don't know what the system will do. You have no way to predict whether any of the code will wipe out anything useful - it may just go into a tight loop.

 

Bob

[RodCastler]

Forcing 5V onto the pin will only work if there's no cartridge present since the mod is designed to toggle that status.

 

Also note - there's 2 different behaviours of the XL OS. Earlier version usually installed in 600XL will instantly coldstart if the cart state changes. Later version will simply lock up the machine then coldstart if you press Reset and the cart state is still different.

Excellent points. And yes, I don't use carts anymore since I am all in for SIO2SD these days so I was thinking of just forcing 5V to pin 11.

 

I now wonder why the circuit based on a 74LS123 mentioned in the first post of this thread didn't work: probably the voltage drop at the 74LS123 was not enough to counteract the existing 1K pulldown.

 

Thank you all for the great replies!

[Bryan]

That might be dangerous... You don't know what the system will do. You have no way to predict whether any of the code will wipe out anything useful - it may just go into a tight loop.

 

Bob

It would be best to use reset to latch the new flipped state so they happen at the same time.

[Rybags]

Really, it's probably just easier to burn or flash a custom made OS that has a coldstart key sequence.

The XL keyboard routine has a bunch of crap that's only usesful for 1200XL, get rid of that and have something like Shift + Option + Delete.

[Fox-1 / mnx]

This is what I use in my 130XE: http://www.abbuc.de/~bernd/tipps/kaltstart-resetschalter-fuer-den-atari-xl-xe.html

[flashjazzcat]

IDEa, IDE Plus, Incognito, Ultimate 1MB, and SIDE/MyIDE soft drivers all have built-in coldstart hot-keys. Worth noting.

[mnemo]

On 3/27/2006 at 7:58 PM, Tschibo00 said:

Hi guys,

after completing the super video, basic switch and SIO2PC upgrade I now installed a hard-reset button (found the schematics on the net) to my 130XE. Here are the schematics:

[snip]

Sorry to dig up this OLD thread, but I was just looking for a cold reset solution and searched further. The mod from the original post can be found here and the post above was missing a part: Where to connect the "RESET" line. Maybe that's why it didn't work.

 

The original article says:

600XL: to the right connector of resistor R45 directly below the modulator case.
800XL: to the left connector of resistor R50 between POKEY (U22) and PIA (U23).
130XE and 800XE: to the upper connector of resistor R40 left to the keyboard connector.

 

Also an addendum by @Fox-1 / mnx on that page: "A 100 µF capacitor is working better in my 130XE."

 

Hope this helps. Has anyone else tried it?