Can i make Ben Eater's computer with a R65SC02P-1 ?

[TechTheGuy]

Hello to everyone!Im new to microprocessors ,but i want to make Ben Eater's computer.The problem is that from ebay it is arrived an r65sc02p-1 . I tried it with arduino (like Ben did) but it reads only 0 even if i hard wire with resistors ea.It spits 0 everywhere.Can i still make it?If yes what changes to the scheme do i need to do?If no can you send me a link for a W65C02S?

[GARTHWILSON]

TechTheGuy wrote:

The problem is that from ebay it is arrived an r65sc02p-1 .

The Chinese counterfeit IC "industry" (I use the term loosely) seems to have taken eBay by storm, and we find that there's a rather small chance that what it's marked is what it actually is. We try to keep the sticky topic "65xx parts sources" updated. WDC is the only one making 65c02's today, and you can find legitimate distributors in the links in that topic. A Rockwell part would be easier to get going on a solderless breadboard because it's not as fast a part (the rise and fall times are far more important for this than the MHz rating); but I don't know where you'll find real Rockwell (or GTE or Synertek or other) ones. Solderless breadboards are the worst of all worlds (or most worlds anyway) for this kind of work. We really would like to see the newcomers' success rate closer to 100%, but the insistence on using solderless breadboards has been holding that back. If you really must do it that way, keep the project size down and keep the connections as short as you can, especially the ground and power connections from one IC to another.

[M0001]

I bought mine from mouser, https://www.mouser.com/ProductDetail/We ... SplB6itg==

[BitWise]

The terminal output shows that the CPU is operating but that its reading BRK instructions which are continually causing the IRQ/BRK vector at $fffe/f to be accessed.

We need to see your circuit. The 65SC02 is pin compatible with the 6502 so pin 1 should be connected to ground (there is no vector pull /VP output) and pin 30 should not be connected (there is no bus enable input).

It may be a working chip.

[TechTheGuy]

Thank you all! I am using this guide https://www.instructables.com/id/6502-M ... uino-MEGA/

I hard wired the resistors but whet it reads returns 0

[BitWise]

RDY, RESB, IRQB, NMIB and SOB should be pulled high with ~3K3 resistors rather than directly connected to 5V.

That is the pin out for a W65C02.

The 65SC02 has the same pin out as the original 6502. Pins 1 & 36 have different uses.

I should try one on my 3 chip board.

[TechTheGuy]

Just tried.Nothing changes.Can you try yourself please?

[BitWise]

I've ordered some G65SC02s but its going to be a few weeks before that arrive from China.

My 3 chip board has sockets for both 6502 and 65C02 chips. On the PCB they overlap so only one can be populated at a time. The 65SC02 should work in the 6502 socket (as does the W65C802). If you look at the schematic you can see that two socket have slightly different connections.

https://github.com/andrew-jacobs/sb-650 ... B-6502.pdf

The firmware in the PIC feeds a JMP ($FFFF) instruction into the chip at startup and looks at the addresses that are accessed. A 65SC02 should access $FFFF and $0000 in 7 cycles like a W65C02. I don't think my W65C02 boot ROM images contains any of the bit instructions that aren't supported on the 65SC02.

[Dr Jefyll]

TechTheGuy wrote:

I tried it with arduino (like Ben did) but it reads only 0 even if i hard wire with resistors ea.

For a 6502 with $00 on the data bus, your machine seems to be behaving properly -- and $00 is what the screenshot shows. But you mentioned hardwired resistors for $EA, so is there a mistake or misunderstanding somewhere? Here (below) is what you need to get $EA on the data bus.

cheers
Jeff

[cjs]

Dr Jefyll wrote:

For a 6502 with $00 on the data bus, your machine seems to be behaving properly -- and $00 is what the screenshot shows. But you mentioned hardwired resistors for $EA, so is there a mistake or misunderstanding somewhere? Here (below) is what you need to get $EA on the data bus.

Yes, this is also how I did it the other day on a breadboard when discovering a wiring error I'd made on an SBC.

This may be obvious, but you should measure the voltage on the data pins of the 6502 itself to confirm that they're actually pulled up and down to the correct values. If they're not, you have a wiring error somewhere, or perhaps bad connections in your breadboard.

[argonn]

This chip might be NMOS 6502, rebranded by Chinese "businesmen" as 65C02. Try running it at higher clock speed (above 100kHz).
I ordered 5 chips a few years ago, got 3 NMOS and 2 CMOS, rebranded as Rockwell 65C02. link: viewtopic.php?f=4&t=4593
The only eBay seller I found that had real WDC chips is from UK, toucano76. Not an ad, just all the others I checked had similar rebrands I got. eBay feedback would suggest desoldered parts, 50/50 NMOS and CMOS being sold as "new" CMOS chips. Some also had R6522 (NMOS) chips with date codes from 2010s… which is clearly not true.

[cjs]

argonn wrote:

This chip might be NMOS 6502, rebranded by Chinese "businesmen" as 65C02....
I ordered 5 chips a few years ago, got 3 NMOS and 2 CMOS, rebranded as Rockwell 65C02.

This is really good to know, since I have a small pile of cheap "Rockwell R65C02Pn" parts; being aware of this possibility could save some painful debugging.

(Also, a bit ironic because I've wanted some NMOS 6502s. They may actually have sent me my preferred chips! :-))

[Chromatix]

I really need to finish my "6502 Fake Finder" project, which should make identifying these re-marked chips much easier. I should be able to order the parts in parallel with the "RIOT Clock" ones, but of course I still need to write the firmware.

[BillO]

It's too bad this is happening. eBay used to be a pretty good place to get stuff. Having said that, I've been pretty lucky I guess and have never ended up with fake chips.

One thing I tend to do, and this may or may not be why I'm lucky, is I go for the sellers with the highest ratings, rather than the lowest price. I usually won't deal with a vendor with a rating under 95%. I wish eBay let you sort according to seller rating. It would save me a lot of time.

[cbmeeks]

The only time I use anyone other than Mouser for chips is when it's something that isn't made anymore. I'd rather pay the $8 for a real 65C02 than chance some $2 fake from China.

When I do buy from eBay (such as sound chips) I try to find US sellers that (hopefully) have vetted the chips and with high ratings.