but why would [spurious reads] cause problems writing to the 65C22?

Here's a stab in the dark.

In the 65c22 a read or write to certain registers clears the interrupt flag for that register. A scenario where you're checking for the flag condition but it's been inadvertently cleared will give you ...

I can see two ways to store an ASCII string in memory.

1. The string to be displayed-one termination byte-
eg:- 5465737400

2. A byte at the beginning of the string location describing the length of the string
eg:- 0474736554

In the first instance you need to test each byte for the end of string ...

Would the-

1) 65c02 running at higher clock rates,
2) 65c816

-ever be considered for embedded video processing.

I'm thinking of cctv type application not image processing.

Can anyone point to a CCTV manufacturer that uses either of the 65c family?

I've seen the Rigol 1102E recommended a lot bu

I picked up a Tektronix TDS 210 on ebay it's small and compact which serves my purposes perfectly well. A programmer is a must, I see some folk have built their own. I used to have a uv eraser for the old 27 series ROMs, but I'm currently using 28 ...

Interesting replies, thanks.

is more of a challenge, without making some minimal assumption,

So. I guess I am being a bit paranoid. I could initialise the VIA port and then I have four LEDs and the LCD avaliable.

So far, the only time the test has failed was when I replaced the 32K RAM with an ...

Hi folks,

I have just taken my 65c02 project off the top shelf again and I'd like to hear peoples opinion of testing onboard memory.

I've just tried a routine that tests zero page using the 55 & AA bit patterns and I put that as the first step of my board initialisation. Straight away I come ...

...but are readily added to PC hardware if needed.

Agreed, my mini atx has one which I use for the programmer.

For my purposes, it's the 'consumer interface' perspective. I think the usb interface would be fine.

I'd really like to be able to just download new code directly into the project, I'm ...

I just added a 65c51 to my 65c02 project board. As a bit of a shortcut I considered one of these for the interfacing circuits -

http://www.ebay.com/itm/MAX232-RS232-To-TTL-Converter-Adapter-Module-Board-/221022603873

Then I came across one of these;

http://www.ebay.co.uk/itm/like/400686965254 ...

So would you have a latch with its own address, and you write to it the bits specifying which IC to address next? Actually, come to think of it, the 6520 does a similar thing. Suppose you had its base address at 0000. Control register A then is at address 0001; and its bit 2 determines whether ...

Regarding the full address decoding and ZP loss penalty of putting I/O in ZP, my workbench computer would lose 76 bytes of ZP (30% of ZP) with full decoding,

How about optimising the use of zp I/O by stacking similar devices at the same address? Controling access to each similar device with a zp ...

Is there any merit in modifying this circuit so that it's all built on a board that includes the nano board itself, enough Ram and a DIP plug that could plug directly into the project ROM socket?

It seems to me such an arrangement would remove the need to run through the; pull (EEP)ROM, erase ...

If all you are doing is inverting a bit why not use EOR?

LDA ZPFPLED
EOR SWCHLUP,X

STA ZPFPLED
STA FPLED
RTS


A couple of reasons, I guess. Insufficient familiarity with the instruction set, I noticed Jeff and Mike used the instruction, but I guess I had fastened on BIT and was trying to ...

Thank you all for you ideas and code suggestions. I think Garth, you were on to the problem with the alignment of the lookup bits in the tables. Anyway this is what is working now.


LEDROUTINE:
;Lamp control routine that toggles individual Led's on or off.
;**Call with X reg holding index of the ...

If it's not for a "certificate", then take a look at my solution, untested as it is, which I posted to GitHUB.

Thank you Michael, I had a look at your code and tried it in my machine. I had written something similar with five 'ROL's in an earlier test routine but hadn't thought to use the EOR ...

As I explain in the section of the 6502 primer though, you must debounce .

That was an informative reference.

Generally, most of this forum's members don't provide solutions when it appears that it is a homework problem.

I know this is a simple problem, but I was just getting very frustrated ...