> Anybody knows what happened to > www.free-ip.com (they used to > offer an open source VHDL
> synthesizable model of a 6502
> core)?

There's a copy which I added BCD support to on my website.
http://www.sprow.co.uk/fpgas/

Sprow.

> Well, you are right with regard to my scope, the fastest I have access to is 200MHz, and it looks fairly sine-ish on it.

Um, you have got all your scope probes compensated for the scope you're using haven't you?
Sprow.

> > Saves a couple of cycles
> Thank you for the sugestion, but according to 6502opcodes.htm the 6502 has neither a cpy $xxxx,Y nor a stx ($xx),y instruction as far as I can see...

My brain sort of said that was the case, and the assembler didn't complain when I typed them in in interactive mode ...

> After looking at the sorting algorithms in the Source Code Repository I
> was inspired to make a contribution myself. I choose to make an
> implementation of the JeffSort algorithm.

I'll throw in a few free optimisations for you:

ldx #0
fill ;tya
;cmp temp,x
cpy temp,x
beq next
;txa ...

> Im programming a 6502 emulator for a NES emulator im making.
> I have the following problem/question regarded de CMP,CPX, CPY Instructions

[Not sure which way]

It's (A-M) and (Y-M) and (X-M),
Sprow.

> Does anyone know of a supply of 65C51/6551A's that are available in
> the UK or failing that in Europe?

6551 at Grandata £2.50
6551A at Cricklewood Electronics £4.50

Sprow.

> I think that almost every program starts with CLD! Why use binary
> coded decimal representation?

The two most recent applications of BCD I have had were
a) a clock chip whose registers were BCD anyway
b) decoding the modified Julian data passed in the Television Service Data Packet as part of ...

> Can this be used in a 6502 computer?

Yes

> And if so, what is the upper limit (ie., max amount of memory)?
> Can I use a 1MB chip?
> Could I use one with more memory?

Any size is fine, but since the 6502 only has a 16 bit address bus you'll never be able to see more than 64k at a time - so a ...

Hi,
The '6502_tips.txt' look good,and well worth making public via 6502.org.

However,the "Combining shift register and counter" tip seems to have an excess CLC in there,which seems unnecessary since the LSRA a two instructions later corrupts C anyway.

I'm sure with the "NMOS branch always" tip ...

Me!
Provided by "small" you mean 10's not 100's.
http://www.sprow.co.uk/bbc/forsale.htm

Alternatively,contact me off list and I can probably find someone with some obsolete stock somewhere in the UK,
Sprow.

In the UK,STV5730A £5.50 from Grandata Limited in Wembley.
No MOQ.
Sprow.

> Does anyone know of any good, clear, well documented / easy to follow
> references for interfacing with a floppy drive?
>
> I can either do it via compact flash or floppy

Good,clear,and well documented are not usually found in the same sentance as floppy controller datasheets.

There are 3 that I ...