Software to disable reset,or hardware modification on amiga.

[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.

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moto

[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.

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moto

[motorollin]

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

--
moto

[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

[motorollin]

For the reset procedure to be modifiable through software, it must be controlled or initiated at least to some extent by software. If this is the case, then surely it can be totally disabled, maybe by using the same method of capturing the reset used by that software.

[EDIT]
From the DiskSafe manual:

It is safest to test DiskSafe first, before using it, because I can't give
any waranty if this reset logic is installed in your computer. Up to my
knowedge, it is present in:

o)  the newer A1000
o)  the A2000 (A to C) series
o)  the A3000 to A4000, and the A1200 (thanks to the reports)

but is not present in *some* (depending on revision)

o)  old A1000's
o)  A500's
o)  A600's

And how it works:

If you press reset, the reset is first captured by the keyboard device,
which again informs DiskSafe and delays the reset, for a maximum of ten
seconds (thus things must go fast). Alternatively, DiskSafe gets informed if
you press the reset replacement sequence or call the ColdReboot() function.

However, this delaying of the reset signal does not work on all amigas,
since some special hardware is required to do this. To keep production costs
(and customer satisfaction) low, C= choose not to install this piece of
hardware into every amiga on the market!


If, let us assume, the keyboard.device COULD postpone the reset, DiskSafe
closes all files open for writing and flushes all disk buffers, thus writing
the bitmap and leave the disk valid. If this operation completes, the
keyboard.device is told to finally start the reset procedure, since the
bitmap of all disks is now safe.

So DiskSafe is able to interrupt the keyboard controller and prevent the reset. It then tells it to continue with the reset once it is safe to do so. Presumably removing this last part would disable the soft reset on a supported Amiga.

--
moto