Re: Hiding code from the User...

From: Professor Dredd (profdredd_at_yahoo.com)
Date: 2001-04-02 15:25:19

If you REALLY want to know the details of how these
devices install themselves into the system and where
their I/O is mapped, here is what I would do.

Get your trusty copy of Anatomy of the C-64 (Abacus)
and open it to the ROM disassy. Enable the cart/device
and start your monitor. Begin with the vector at $FFFC
and trace the power-up/reset routine. Use the Anatomy
disassy for comparison purposes.

One thing to keep in mind about RAMLink, RAMDrive and
other such devices is that they generally contain user
data. If you intend to program RAMLink's hardware
directly, you must make NO ASSUMPTIONS whatsoever
about the configuration or content of the device.
Otherwise your program may destroy data, or at least
make it unaccessable to the user.

--- ncoplin@orbeng.com wrote:
> Hi All,
> 
> I was wondering if we could share what we each know
> about how various
> utility cartridges /expansions go about installing
> themselves on the C64 and
> them hiding from the User.
> 
> For example:
> KCS Power Cartridge has a 6810 (128byte RAM) which
> is in the I/O area and
> vectors are routed through this to switch in /out
> the ROM expansion
> 
> The FINAL Cartridge III mirrors 512 bytes of ROM
> into the I/O space for the
> same reason
> 
> Other carts (eg freezers) use a combination of RESET
> and NMI to wedge
> themselves at the push of a button.... 
> 
> But how to do some of the other devices work:
> 
> RAMLINK (in particular where does RLDOS live)??
> Epyx FastLoad (there's only a ROM and logic here)??
> Action Replay (EPROMS, RAM and Logic)??
> 
> How do the C128 carts do it?
> 
> 
> PLEASE TAKE NOTE:
> 
> The contents of this email (including any
> attachments) may be
> privileged and confidential. Any unauthorised use of
> the contents
> is expressly prohibited. If you have received this
> email in error,
> please advise us immediately (you can contact us by
> telephone
> on +61 8 9441 2311 by reverse charge) and then
> permanently
> delete this email together with any attachments. We
> appreciate
> your co-operation.
> 
> Whilst Orbital endeavours to take reasonable care to
> ensure
> that this email and any attachments are free from
> viruses or other
> defects, Orbital does not represent or warrant that
> such is explicitly
> the case
> 
> (C) 2000: Orbital Engine Company (Australia) PTY LTD
> and its
> affiliates
> 
> -
> This message was sent through the cbm-hackers
> mailing list.
> To unsubscribe: echo unsubscribe | mail
cbm-hackers-request@dot.tml.hut.fi.


=====
Get a FREE 6Mb webmail box from go6502! - http://www.geocities.com/profdredd

As low as 2.99% Intro APR from NextCard! - http://www.nextcard.com/index6.html?ref=aff0074521

PayPal is the FAST FREE and SECURE way to send money! - https://secure.paypal.x.com/refer/pal=profdredd%40yahoo.com

__________________________________________________
Do You Yahoo!?
Get email at your own domain with Yahoo! Mail. 
http://personal.mail.yahoo.com/?.refer=text
-
This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.

Archive generated by hypermail 2.1.1.