Very small 6502 project.

[JenniferDigital]

What's the smallest package 6502 that can be bought, not necessarily still in production?

[cbmeeks]

Maybe QFP-44?

https://www.mouser.com/ProductDetail/We ... Ez72ae0%3d

[ElEctric_EyE]

PLCC-44?

https://www.ebay.com/itm/W65C02S8PL-10- ... SwDN1UNf6v

Unfortunately, WDC does not spec the size of each but looking @ another manufacturers website for 44-pin QFP and PLCC, I found that the PLCC package is 17.4mm square edge of pin to edge of pin. The 44-pin QFP package is 12mm square edge of pin to edge of pin. So cbmeeks was correct.

This was the spec sheet I was looking at.

[JenniferDigital]

12mm a side is pretty good! I could make a pocket computer with one of those at a reasonable size, that doesn't give me a funny gait.

[GARTHWILSON]

Remember you can put parts on both sides of the board too, nearly doubling the density.

[JenniferDigital]

A very good point indeed, and I've also seen boards made slimmer by cutting a hole for a QFP chip to sit in down side up too. All this helps with challenging design envelopes.

[cbmeeks]

DigitalDunc wrote:

A very good point indeed, and I've also seen boards made slimmer by cutting a hole for a QFP chip to sit in down side up too. All this helos with challenging design envelopes.

In a hundred years I wouldn't have thought of that. Now that is an interesting idea!

However, I think you would need bigger boards if you did that with too many IC's. But a great idea if you want slim.

[whartung]

There may well be embedded 6502s on very small chips as well, only exposing the pins that they care to extend.

As well as simulator cores on small micro controllers.

Guess it depends on what the real goal is.

[kakemoms]

And you have very small cpld's that can accomodate a 6502 core. The MachXO3-1300 can be supplied in a 36-ball package of 2.5mm x 2.5mm...

Although not so easy to solder, it has 8KiB of RAM inside.

[JenniferDigital]

Well, my QFP 6502's came yesterday.

I did give soft-core 6502's consideration and I think in this instance, I'll be happier with the WDC part. Doing 6502 on CPLD or FPGA should be further down the line for me after I had my confidence knocked the other day. It took me a while longer than it should have to draw the library part as I couldn't quickly find any reference to it's footprint, which is on a 0.8mm pitch.

I'll happily post a copy of the library part (warts and all) when I've finished tarting it up should anyone want it as their starting point. These shouldn't be hard to solder after all the trouble I wen't to with the STM32's I've been using on some other stuff I've been doing.

[EugeneNine]

might be worthwhile to use http://www.westerndesigncenter.com/wdc/ ... s-chip.cfm since you get the 6502/rom/ram all in one to same more space.

[Mike Naberezny]

DigitalDunc wrote:

12mm a side is pretty good! I could make a pocket computer with one of those at a reasonable size, that doesn't give me a funny gait.

The Mitsubishi M38869FFAHP is also a 12x12mm package (datasheet page 109) but it's a microcontroller that has 60K flash, 2K RAM, and built-in peripherals like GPIO, UART, and I2C on a single chip. I found this chip in a car radio (photos). It uses a Mitsubishi 740 family core, which has a superset of the NMOS 6502 instruction set. It will run normal 6502 code or you can use the extra instructions. It's low on RAM for a general purpose computer but the datasheet says it has a mode where external RAM can be connected. It is available from surplus dealers and I bought some from Utsource a few months ago. They were USD$8.22/each. I've tested a couple of them and they were functional.

[JenniferDigital]

Firstly, my apologies to everyone for not logging on in quite a while. Mike Naberezny, I find that Mitsubishi part quite intriguing and I thank you for the link.

I shall take a good look at it over the next few days.