First of all, sorry if this post ain't strictly a 65xx related one, but I can't find any other forum like this with experienced computer people. I'm looking for a CLA, really compact, so stackable as an RCA, small and fast. Overall, the best pure CLA ever (no LFA, no KSA nor any other parallel prefix adder based on the CLA). I apologize for asking too much, but all my CLAs look horrible and are extremely messy. Help is very appreciated.

You might find what you're looking for over on the electronics stack exchange. For example
https://electronics.stackexchange.com/q ... its-adders

I see. Your CLA either is compact\small, stackable, or fast.
And what you seem to need is a good\practical compomise between those three things.

Would suggest to go for a 74882 topology,
means a two bit ripple carry plus carry lookahead.

If this won't help, please post some of your CLA designs so we could try to figure out where you got stuck...

Thanks! That forum's perfect

Thank you so much! My CLAs are stacked as a triangle (carry logic), here's how my 3 bit one looks:

Hmm, I think we need to distinguish design from presentation - today's word is Skeuomorphism, and the problem I see here is that making the circuit look like a tangle of wire, switches and light bulbs isn't helping to communicate the design. Could you redraw that as logic gates and straight wires with right-angle bends, and preferably proceeding left-to-right or perhaps top-to-bottom? I think we've mentioned several web-based simulators here previously... try
viewtopic.php?f=8&t=4189&p=46307&hilit=browser+simulator+logic#p46307
and perhaps
viewtopic.php?f=1&t=3370&p=39106&hilit=browser+simulator+logic#p39106

It's a normal, pure CLA. Its carry logic is just stacked as a triangle.

It may be, but I'm afraid I can't tell by looking, and I'm not inclined to study it. I don't want to be unhelpful - in fact the opposite - I'm suggesting you make it as easy as you can for others to understand what you're asking. See how logic is conventionally presented, and try to present it conventionally.

LBSC, sorry to say this:

This lump of wires, switches and gates isn't easy to read.
It doesn't too clearly come out which wire goes where.
The switches are not labeled, so it's hard to tell which of the switches does what.

You don't have to install a complete schematics CAD program on your PC, of course.
It would do to manually re_draw the schematic with paper and pencil, then to scan it.

;---

IMHO, the most powerful design tools are paper and pencil,
unfortunately they also happen to be the slowest design tools.

To put it this way: when I had been building hobby CPUs,
there sometimes was a pile of scratch paper on my desk at about the size of the phone book...

But manually drawing a a lump of logic gates a few times can be helpful for understanding
how it works... and how to simplify/optimize it.

From time to time Garth posts a photo of a hand-drawn diagram - and that's fine! No software needed.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Hmm... after half an hour of staring at LBSC's lamps\gates\switches picture,
I'd say it follows a similar concept like the 74F381\74F382 carry chain.

Some infos on the innards of the 74F381.
Fairchild 74F381 datasheet at Digikey.

I entirely agree. But I'm forced to admit one thing. The pictorial really does have a certain charm , and perhaps makes the project seems more achievable. Is this the style of presentation used by Minecraft?

BTW, LBSC, you're allowed to attach images to your posts here. It's unnecessary to use imgur; also somewhat undesirable, since it's not permanent. Cheers,

Jeff

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

Teach me how to draw well, please.

Minecraft uses blocks, I made this with a logic simulator. I always use it to test my designs before I actually build them in Minecraft.