it’s inspired by RENE 1 and a bit of RENE 2 
I wanted the simplicity/ease of use from Rene 1,
but needed a number of things from Rene 2 (but without some of its complexity)
but bare in mind:
a) RENE code base is NOT open source/available.
so ALL code is my own, and my implementation of how I believe RENE works from the manual…
b) I don’t own, and have never used RENE
so its my interpretation of how it works…
given the above, you can see how its my interpretation…
pretty much its how I would LIKE Rene to work, what I think makes it special given what I ‘know’ ( basically read in the manual, seen in videos etc) … if thats true of Rene hardware or not, I cannot say 100%
I also have taken some ‘liberties’ in my interpretation…
with hardware modules like Rene, they have to have a certain level of self contained functionality to justify their price/place… e.g. you cannot expect a user to have 2 Renes , or need/want another module along side it… as it implies more $$$, but this is at the cost of ‘modularity’
with software modules, this is not true - so an exact clone is ideal/needed… as you can use modularity without extra cost.
this is one of the reasons, Ive not done the whole Z layer aspect of Rene 2, frankly, I think on the hardware module its confusing, both in UI and concept - some times simple is better, less is more esp. if you can achieve similar using other modules.
similarly there are UI differences…
Ive implemented scales within CART, rather than just selecting notes on the ‘grid’ as Rene does…
On Rene, MN approach is nice, because not only is it flexible, but the touch pads make it quick.
On the SSP it feels a bit ‘clunky’, and scale selection felt quicker and more natural.
If anything, I see this divergence actually increasing… so its not something I apologise for, nor regret.
e.g. Ive implemented the Rene CV and MOD inputs, just because I wanted (personally) to see how they felt, and how Id used them ‘as designed’.
but reality is, CART could pretty much ditch most of the (confusing) FUN page, and I could just implement every ‘mode’ as separate CV inputs… ie. you wouldn’t not have to choose only 1 CV and 1 MOD mode, but rather could combine them.
this would be much more powerful than Rene… again the different between hardware and software, extra CV = $$ and panel space for Make Noise, but costs ‘nothing’ for the SSP.
similarly, I actually think the way X/Y CLK is used to derive C , is pretty basic on Rene.
(so much so, I confirmed it with Tony @ Make Noise 
) - I originally implemented a much more interesting way… so I may add that, perhaps optionally, as a future update.
so yeah, Rene is inspiration only, from a module Ive always wanted.
at this point in time, I wanted to have it close enough for me to get a feel for it, and not to (imho) lose its feel, and what makes it special … but not slavishly ‘clone’ it.
I dont know if Ive achieved that, but I am happy that CART (as its own thing) is great.
again, Id like to re-iterate, CART took me a LOT of time to code…
Rene is a complex beast, even researching how it works, took time, esp. due to an ‘imperfect’ manual, as I say, I had to reach out to Tony at one point for clarification… as many YouTube videos just ‘gloss’ over workings… as often to USE something, doesn’t require you to know HOW it works.
then from that research, I then had to implement… with so many inputs and interactions between modes etc, this required a lot of work , and inevitably during my testing and using, I had to re-work things when I was not happy with how things ‘combined’.
so yeah, it took many weeks of development over a longer period of time… as Id put in down occasionally, just to get a break, and also ‘fresh eyes’ on the problems and goal.
But Im happy with the result… as I say, I now use it on pretty every SSP patch… not only for traditional sequencing functions, but also for modulation (tip: use glide when using as a sequenced modulator )
I’ll also say, it gave me a much better appreciation for the work Make Noise have done on Rene, sure some may find it a bit daunting, but its no doubt a classic. definitely worth the 550 euros!
I’ve considered buying one… but ironically, Ive learn that I love the simplicity of Rene 1 over Rene 2, but Rene 2 has some features Id miss… thats why CART is kind of a hybrid of the two.
btw: I should point out, that Rene is not the only cartesian sequencer around… but rather the most well known/classic in Eurorack
