Hi out there,

WDC announced today on facebook.com, that the CMOS replacement for the 6551 is now available at mouser.com.
Thats great, cause the original NMOS chips are very expensive on ebay and these chips are half the price as new part instead of a used one.

Here's a link for the product at mouser:
http://it.mouser.com/ProductDetail/West ... 5LybCTWxI=

Mario.

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How should I know what I think, until I hear what I've said.

The NMOS ones had a couple of bugs that I consider to be pretty serious, ones that were corrected in the CMOS version in the 1980's. I have been using the CMOS ones since the late 1980's, with no problems. After California Micro Devices (formerly GTE), Rockwell, and other companies quit making them, WDC started, and theirs were rated for 14MHz; but their initial ones had a bug with even parity or something like that. (Who uses parity though?) I wonder if it's fixed.

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

That's great news. I've been waiting for them to be available. My SBC-2's can now use a faster clock too.

Daryl

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Thanks for that, Mario -- I'll be changing my design back from the 2692A. Though I have developed an appreciation for how powerful it is, a system with the 6551 will be simpler. The second computer, though ...

I think it was BDD who said that his design was "a moving target". I know the feeling now .

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

It simply does less stuff, and, as you point out, the 2692A needs a bit of trickery to get up and running. I'll skip trickery this time around, I think. However, the 2692A is far more powerful, and once I have the training wheels off, I'll be returning to it, and anybody with more experienced should take a look at it.

In what way? I could not find a 2692 on NXP's website, but I was just looking at the 2691 (is it the same thing with only one channel?) and was not impressed.

• It does not have DSR, DTR, DCD, or RI like the '51 does (although I've sometimes used those for general-purpose I/O since I'm not interfacing to modems),
• it does not go any faster, and in fact has the same table of bit-rate selections,
• you can go above 19.2kbps with the 16x input like on the '51 (or it can reach 38.4kbps with the crystal only if ACR<7>=0),
• it has more buffering but that's because it's typically used with processors whose interrupt performance is not as good as the 6502's,
• it has approximately the same interrupts,
• same error detections (overrun, parity, framing, and false start),
• same choices of frame length, stop bit length, and parity,
• plus full-duplex, echo, and transmit break, like the '51 has.
• Both have onboard crystal oscillators, and both operate on 5V.

On the plus side, it has a 16-bit programmable timer/counter like the '22 has, a low-power mode, and the DIP is skinnier.

_________________
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?

You should use the 26C92, it's a newer device that has an 8 byte FIFO (transmit and receive) plus faster access time.

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

That's great news. I recently bought some of the PLCC chips from the UK which have a manufacture date of 2012. However, none of the WDC documentation shows the pinout for the PLCC version. I'm guessing it's the same as the DIP (pin number per pin number) as some older Rockwell data sheets show that. In any case, Mouser in the US shows them in stock, so I'm adding some DIP versions to my current order Again, thanks for the heads up on these... in some emails with WDC late last year, they said there were coming soon, glad they made it.

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Regards, KM
https://github.com/floobydust

It's a little different. See page 4 of the data sheet at http://archive.6502.org/datasheets/wdc_ ... 0_2010.pdf

_________________
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?

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

Thanks guys, I have that data sheet. Problem is, it only shows the DIP version (28-pin) and the LQFP version (32-pin). What I have is the PLCC version (28-pin), hence my concern on what the pinout is.

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Regards, KM
https://github.com/floobydust

My apologies. Try page 8 of this one: http://archive.6502.org/datasheets/cmd_ ... ar2000.pdf

_________________
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?

Do we know about any other source for these WDC 6551 chips than Mouser? I wanted to buy a couple to have in store just in case, but the lowest shipping price from Mouser is $30 and that makes the deal a bit unbalanced. I haven't been able to find anyone else selling these chips. Jameco don't have them, and in any case they seem to be in the process of scaling down their WDC selection (luckily I got some WDC CPUs from Jameco earlier while they were still stocked).

Incidentally I noticed Mouser lists two types of the 6551, an S version and an N version - the latter is 5V, the former 1.8V-5V. There's no mention of this on the WDC site. Anyway, I would like to find a source for these chips which will ship with e.g. USPS international priority which is about a third of what Mouser currently charges.

-Tor