Hi Guys,

I'm looking for a WDC65C02S in a DIP-40 package but I have no money. Is there anyone in the Michigan area with a spare that might consider trading me for some old books I found in storage (circa 1979-1981)? The books are in excellent condition. Here's what I have;

(1) Programming the 6502, Rodney Zaks, Sybex.
(2) 6502 Applications Book, Rodney Zaks, Sybex (including purchase receipt, 10/12/79)
(3) 6502 Software Gourmet Guide & Cookbook, Robert Findley, Scelbi Publications
(4) Apple Machine Language, Don Inman & Kurt Inman, Reston Publishing Company, Inc.

Thanks much...

Cheerful regards, Mike McLaren

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Greetings,

Thank you for the kind offer. I really appreciate it. Unfortunately, I'm not sure I can handle the mux'd bank data on the '816. I'm trying to use a PIC as a ROM/Monitor boot loader of sorts.

Thank you again...

Cheerful regards, Mike, K8LH (Michigan, USA)

Again, if you don't need more than 64K of address space, you can totally ignore the bank byte, and still get a ton of benefits from the '816. You don't have to latch, decode, or use the bank byte. Just make sure nothing is putting data on the data bus during phase 1 when the processor is putting the bank byte out (which you will ignore), and you'll be fine.

_________________
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?

Gosh, I appreciate the offer from BDD and the gentle nudge toward what I suspect is a much nicer processor with a lot more capabilities. I'm just not that familiar with the '816 which means I'd have much more research ahead of me before I would be able to do something useful with it (I'm a slow learner). I'd also have to dig up a PLCC-44 socket.

I came close to finding a 65C02 today. I cleared a path to a closet full of old Apple stuff and up on one of the shelves with boxes of spare parts I found an Apple //c system board. Inside was a new replacement board minus the 65C02 processor (bummer!). Also found a stash of Apple II ROM sets, including a Programmer's AID #1 ROM (341-0016-00), and some Apple //e ROM sets, including some of the 40 pin MMU (344-0010) and IOU (344-0020) chips. I also found a couple NMOS 6502A processors.

Do I understand correctly that I can't stop the clock on the NMOS 6502 because the internal registers are dynamic rather than static? If that's the case, then it seems I really need the 65C02, yes, no? Briefly, here's what I'd like to do. I've got an 80-nsec Toshiba 512K x 8 SRAM chip that I'd like to use as a single 64KB block with the 65C02. I'd like to use a PIC microcontroller to generate the processor clock signal and to load a monitor program into RAM at start up. I'd like to come up with some sort of Kim/Sym/Aim type front panel that would allow me to modify memory and run or single step the processor. Any input is welcome.

Thanks guys... Regards, Mike

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

The '816 is available in DIP as well.


Right. Non-WDC 65c02's can be stopped indefinitely with phase 2 high, and the WDC ones made in the last 15+ years can be stopped in either phase. NMOS ones will lose their registers' contents if you stop them. You'll want the CMOS anyway for the extra instructions and addressing modes and the fact that the bugs are fixed.

Quote:

I'd like to come up with some sort of Kim/Sym/Aim type front panel that would allow me to modify memory and run or single step the processor. Any input is welcome.

The AIM-65 computer with the NMOS 6502 used a circuit that caused an interrupt at every instruction IIRC to get it into the monitor program. IOW, it didn't really stop, but after each instruction, you'd be put in a routine that let you look around at the registers and status and memory. With a CMOS one you can actually single-cycle it and see what's on the buses at each phase-2-high time, which would mean two to seven times per instruction. If you feed the clock circuit with a pushbutton, you'll have to debounce it. This is discussed in the primer at http://wilsonminesco.com/6502primer/ClkGen.html.

I'm 2000 miles away from you (you originally said "in the Michigan area), but unless I were in your neighborhood, there's going to be postage or driving expense anyway, so maybe I should just send you a 65c02 from here. It will probably be a 2MHz Rockwell one; but I'm not sure the newer 14+ MHz ones are best for new builders anyway. (I do have 816's, but not in DIP like I have 65c02's and 6512's and a few 6502's.)

_________________
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?

(Oops! Lots of activity on this topic just as I finished preparing to post!)

Hi, Michael. Allow me to echo the nudge (so to speak ) toward the '816. Maybe it's hard to believe that this SuperProcessor has a secret identity, and is willing to play the role of a meek, mild-mannered 65C02. But that is the case. Without any action by you, it'll automatically power up in emulation mode and stay there as long as desired -- indefinitely, if need be. As BDD says, the learning curve isn't a prerequisite.

But if DIP-ness and 8-bit-hood are what make you comfortable then I'm willing to donate a Rockwell 'C02 to your cause. Or accept Garth's offer. You are right, BTW, about not being able to stop the clock on an NMOS part. (The RDY input can be used to single-step an NMOS chip without stopping the clock but that's more nuisance than it's worth, IMO. The interrupt technique Garth mentioned is better. Or stick with your plan to actually stop the clock.)

How exactly do you plan for the PIC to write to the 65xx's RAM? Are you planning to float (tri-state) the 65xx address bus so the PIC can temporarily assume control of those lines? NB: Rockwell parts have no BE input and thus cannot float the address bus.

FWIW there's an alternative technique, one which doesn't require the 65xx to tri-state the address lines. It drastically reduces both the amount of wiring for the load circuitry and the number of I/O ports lines the PIC will need. Mainly you would need just 8 output bits from the PIC (not 24) plus a few more bits used as strobes. It's something I planned to write up "someday" for 6502.org. Maybe the time has come.

cheers,
Jeff
ps- a brief explanation (and not very beginner-friendly): Need to write, say, EA to address 200? Clock the following bytes onto the data bus one by one: A9 EA 8D 00 02. Some simple preliminary steps cause the CPU to digest this as a two-instruction program: LDA #$EA then STA $200. Repeat as required for subsequent bytes to be loaded. A simple hardware hook prevents bus contention.

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

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

_________________
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?

_________________
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?

Welcome, Michael!

Garth: if the PIC controls the clock (maybe by toggling an output pin) then surely it's fast enough to control everything it needs to - it just needs to sort everything out between each clock toggle.

Cheers
Ed

_________________
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?

It sounds like this project I posted about. They use the PIC as ROM.

http://hackaday.com/2013/02/08/another- ... /#comments

Another take on the 6502 computer

viewtopic.php?f=4&t=2436

Mike,

I would love to learn how to do this. I have a Pikit 2 and some basic pics.

I know where to get the 6502s and I wouldn't mind sending you some but I would love more to learn how to do it on a 65C816S.

Chuck