Re: Apple Integer BASIC firmware card

[SynABit@kc.invalid (Dennis Doms)]

In article <1evw1m4.1r08oe61m9jxcwN%dempson@actrix.gen.nz>,
dempson@actrix.gen.nz (David Empson) wrote:

>Stephen Shaw <xstephenx@apple2.org.za> wrote:
>
>> You can use them to "break" copy protected software. When you flick the switch
>> which protrudes out at the back of the card in generates a non maskable
>> interrupt (NMI).
>
>You're thinking of a different card, such as a "Wildcard".
>
>With the Integer BASIC firmware card, all the switch does is set the
>initial state of the latch which determines whether the card is
>overriding ROM when you press Control-Reset.
>
>You can use it to reset into the monitor without any chance of the
>software intercepting the reset operation, but this is more intrusive
>than an NMI.

Without going into too many details... sometimes this is enough. Until
later, many programs didn't bury key data in the video screen or other
areas where the reset would necessarily render the program
unrecoverable. You could then write the memory image to cassette (in
blocks, if necessary, to capture the entire range), boot DOS, reload
the raw dumps, and examine them.

If you could recover the disk interface routines (often based only on
a slightly modified RWTS and command interpreter, especially if the
software emulated Apple file access) then you could go to work on the
original program disk.

You could also install a patched ROM to try and capture the "critical"
areas, in effect making a "poor person's Wildcard".

All this presumes you have the Old Monitor ROM installed so that the
reset won't cause a system restart.

Note that in the IIe ROM (if I recall correctly), Apple even added a
routine to overwrite 2 bytes per 256-byte memory page throughout RAM
to frustrate recovery of an intact memory image (which never gets
executed if you have the Integer Card and Old Monitor activated),
which is one reason that card could be handy for debugging on a IIe.

>With a Wildcard, there is a button attached to the card which generates
>an NMI.  This is intercepted by firmware on the card, which then does a
>memory dump directly to disk.

-- 
Dennis Doms  SynABit@kc.invalid
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