Apr 152011
 

Nilquader and I decided to release our Verilog code (based on Nocash’s decryption of the algorithm) to “emulate” the ACID protection chip of the Amstrad Plus. So, you can now find it in the ACID article of the CPCWiki and right here in this posting:

Selec All Code:
1
 

But this isn’t everything about the ACID. We also found a timing problem during the investigation with a logic analyzer, which you can see here:

ACID initialisation by Grim

ACID initialisation (by Grim)

You will find glitches on the /CCLR line which show that the SIN contact should be changed… All in all it is possible to use a fast flip-flop to change the SIN signal when such a glitch occurs (see picture below).

Flip flop for ACID replacement

Flip flop for ACID replacement

You see, this is a very simple schematic, but it isn’t much cheaper than a CPLD, which emulates the full ACID and it comes with a disadvantage: it won’t work with a reset, so you always have to switch the CPC off and on again.

So, have fun with it – maybe Bryce will change his cartridge design and support this solution in the future :-).

Oct 212009
 

Zarkon started a thread in the spanish CPC board at mforos.com about the ACID protection of the CPC+ cartridges. This small protection chip is the last part of the CPC which isn’t well known and without this chip it isn’t possible to develop any new cartridges for the CPC 464+, CPC 6128+ or the GX4000.
So if you are able to help with analysation – maybe because you know directly the details of this chip or you have knowledge about electronics – then please have a look at the thread in the spanish CPC board. Most of the entries in this thread are spanish, but you can translate it with Google which makes the thread at least understandable.

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close