Software to disable reset,or hardware modification on amiga.

[nikodr]

Hello!I am sure many people will have faced this:Let's say that you have your computer working and that accidentally you press the 3 button combination that resets amiga.(for a million of reasons!)

1)Is there a hardware modification that can block or disable reset ?Is there a software that could stop reset from happening?

Is there a utility that could make a towerized amiga switch off like the pc's do?

2)off topic but is there a pc program or utility that could create a ram disk like the amiga has?Or a rad disk that could preserve the contents when i reboot? (i doubt the second could happen,but you never know!).

3)off topic again:I am thinking of buying a classic ppc phase 5 card and a tower to have an amiga os 4.0 machine.
What is the maximum ammount of ram that a classic ppc machine can have and that machine is :1200 ppc 603 phase 5.If it is only 256 it's not much compared to the amiga one systems having so much ram!(and again in modern times the more ram the better,256 mbytes of ram is so little for today standars even for amiga os 4 and amiga).

Thank you!

[rkauer]

nikodr wrote:
Hello!I am sure many people will have faced this:Let's say that you have your computer working and that accidentally you press the 3 button combination that resets amiga.(for a million of reasons!)

1)Is there a hardware modification that can block or disable reset ?Is there a software that could stop reset from happening?

Is there a utility that could make a towerized amiga switch off like the pc's do?

2)off topic but is there a pc program or utility that could create a ram disk like the amiga has?Or a rad disk that could preserve the contents when i reboot? (i doubt the second could happen,but you never know!).

3)off topic again:I am thinking of buying a classic ppc phase 5 card and a tower to have an amiga os 4.0 machine.
What is the maximum ammount of ram that a classic ppc machine can have and that machine is :1200 ppc 603 phase 5.If it is only 256 it's not much compared to the amiga one systems having so much ram!(and again in modern times the more ram the better,256 mbytes of ram is so little for today standars even for amiga os 4 and amiga).

Thank you!

 1) No chance! The Amiga "soft" reset is made by hardware...:crazy: But you can make a hardware device to shut down the Amiga, if it uses an ATX PSU (look on Aminet).

 2) You can create a sort of RAD: device on winblows, called ramdisk (since DOS4.11...), just toss it on config.sys (even on XP!) :lol:

 3) Maximum in a BPPC is 256Mb!

[amigaksi]

On the Amiga 500, you can cut the Reset line and the keyboard will still work but the reset will no longer work.  On the A1000, you can write your own kickstart which gets preserved even after a reset.  There was some utility for a VD0: device that seems to get preserved even after CTRL-A-A.  

If you are using some modified power supply that's ATX compatible, you should be able to control the on/off with a simple switch that can be triggered off from a parallel port or some other port.  You can use a hard drive interface and put a flash drive or RAM drive in and have as many megabytes of RAM as the largest partition allowed by your OS.

[zipper]

Depending on the model of Amiga, this might help (old A1000, A500, A600 don't have necessary reset logic) to delay the reset:
http://main.aminet.net/pub/aminet/disk/salv/DiskSafe.lha
"Keeps disks valid from accidential resets by catching the reset signal and writing the bitmap information first."

[motorollin]

IIRC, the hardware reset initiated by the keyboard only kicks in once the keys have been held for several seconds. Prior to that, the reset is handled by software. That's why if the Amiga hangs and you do Ctrl-A-A, you have to hold it down for several seconds because the software is no longer responding, so you have to hold the keys until the hardware reset kicks in.

I don't know what part of the software controls the software reset, but I'm assuming whatever it is could be patched to ignore the key combination. If I'm right, that would mean that a brief press of Ctrl-A-A would no longer have any effect, but holding the keys to initiate the hardware reset would.

--
moto

[McVenco]

motorollin wrote:

IIRC, the hardware reset initiated by the keyboard only kicks in once the keys have been held for several seconds. Prior to that, the reset is handled by software. That's why if the Amiga hangs and you do Ctrl-A-A, you have to hold it down for several seconds because the software is no longer responding, so you have to hold the keys until the hardware reset kicks in.

I highly doubt that. That way every piece of software (including games and demos with custom bootloaders etc) all should have a built-in code which allows an immediate reset when the three-finger salute is given.

I never encountered a game or demo (booted from floppy) that would not instantly respond to Ctrl-A-A. My guess is the reset command is burned somewhere in the Kickstart ROM (but if you look at the Kickstart being software, then you're right moto :-))

[InTheSand]

nikodr wrote:
...accidentally you press the 3 button combination that resets amiga.

Err... How do you accidentally do this??! I'm curious! :-)

 - Ali

[motorollin]

McVenco wrote:
I never encountered a game or demo (booted from floppy) that would not instantly respond to Ctrl-A-A. My guess is the reset command is burned somewhere in the Kickstart ROM (but if you look at the Kickstart being software, then you're right moto :-))

Precisely. If it is somewhere in software, my guess would be kickstart. Which means removing it is a case of patching a kickstart ROM and BlizKicking it, inserting it in to a KickFlash, or burning it to a new ROM chip.

--
moto

[Krusher]

AFAIK reset is handled by the CIA and not software.

[motorollin]

@Krusher
So why does you sometimes have to hold the reset keys to make the machine reboot if it hangs?

--
moto

[Krusher]

motorollin wrote:
@Krusher
So why does you sometimes have to hold the reset keys to make the machine reboot if it hangs?
...

I never encountered that situation  :-?

Oh and explain why you can reset an Amiga before Workbench disk is shown on screen? And even during the selftest (you know, the gray/white screen during powerup)

[motorollin]

I have, if the system hangs really badly. You have to hold Ctrl-A-A for a few seconds before it actually reboots.

--
moto

[Castellen]

The system reset is interpreted and generated by the system gate array (Gary), the CIA only handles the serial communcations with the keyboard and cannot physically generate a system reset.

Reset is sent from the keyboard by generating a long pulse (I forget the exact timing, probably 100ms or so) on the clock line.  This is detected by Gary, which then generates a logic low on _KBRST, therefore causing a system reset. That's obviously why _KBCLK appears at Gary, but not _KBDAT, as the clock line is otherwise completely useless by itself.
By the way, the _ in front of a signal name means that it's active low, in case you didn't already know.

The system software should have no affect on the reset operation.  If reset control had to be actioned by the CPU, but the CPU was in a frozen state, how would you ever be able to reset the computer???  Think about it.


So to answer the question of disabling keyboard reset:
This could probably be done by lifting the _KBRST output pin from Gary (pin 36).  There's an external pullup on this line, so it would correctly reside in a logic high state.

Not sure if Gary _KBRST is used for anything else, so it might be better to disconnect the _KBCLK input instead (pin 44).  Note that you'll probably need a pullup resistor to 5V on this disconnected pin if you do this.


And how do you "accidentally" press the reset key combination anyway?  I could understand if your hand was 12" wide and you typed like a hyperactive gorilla.  But most people aren't quite that badly mutated...

[zipper]

From DiskSafe docs:

"DiskSafe" is a tiny dos.library patch that, uhm, keeps disks safe - from
invalidation by an accidential reset.

If you hit the reset key combination on the keyboard, the amiga usually
stops all disk IO operation and does not update the disk, usually leaving it
completely damaged. When booting again, the filing system tries to repair
the damage - this is quick and O.K. for disks, but takes long for big HDs
(usually around 20min per GB) and is thus not acceptable.

"DiskSafe" installs a patch that completes all disk IO before the reset
actually is allowed to occure and thus leaves the disk validated, even when
you hit reset within a disk IO operation. But in order to make this working,
some special hardware must be present, which Commodore build not into ALL
amigas, read the Requirements

However, DiskSafe 1.18 offers an "replacement" for the reset key that works
for all Amigas. Check the  Config section of this guide how to do that.

Starting with release 1.10 DiskSafe can be setup to protect the ColdReboot()
library function as well, hence protecting the system from accidential software resets.  (Etc.)

[Castellen]

Good point, which Amiga model are we talking about exactly??
It's true that reset operation does vary quite a bit between models.