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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?

Thank you!



Glad to hear it! I've been trying to complete my breakout board PCB in the main 65C816 series but I plan on making a Hex Display episode in the next couple weeks.



Yeah, I went the MCU route for a few reasons:
- it can be programmed after assembly, unlike the ATF SPLDs, so I can outsource assembly to a site like JLCPCB, and thus make use of 0201 components to make it fit under the display
- I don't need special hardware to program it (like SSOP ZIF sockets...)
- it has a built-in oscillator for easy display multiplexing
- it can be programmed with well known, available tools like the Arduino IDE

One issue is the speed of interrupts prevents the implementation of a register in a reasonably fast circuit (one clock cycle of the MCU is 125ns, of which you need a few to interrupt and read the pins...).
If you need latching of the value, you need an actual logic IC in front to do it quick enough. I managed to fit an ATmega MCU + a 74LS573 latch under the display recently, but I have yet to order this one.
Someone suggested using a PIC microcontroller's configurable logic cells to achieve the speed needed in a single IC, but I haven't tried it yet. You can only map 8 pins to the cells' inputs but you need 9 with the latching signal.

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BB816 Computer YouTube series

So managed both versions, common anode and common cathode with a 16V8. On the common anode you will definitly need a driver, otherwise the display is to dark, because on high level the current driving all segments is to low. So here a little driver with a BC557 will do the trick. (see in my github repo: https://github.com/willie68/WCPLD. For cc and "normal" display you will not need this, but have to look at the datasheet.
One pin (Cathode or Anode) is always connected directly to the clock signal of the 555, the other to the /OEA. See comment in common anode part how to connect the BC557 driver, because this is inverted, too.

I didn't get an /OE in the logic, always get a "excessive number of product terms".
Anyone know how to connect a programmer (in my case a TL866 pro II) directly to a soldered 16V8 for ICP?

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don't count on me, i'm engineer (Animotion)
my arduino pages: http://rcarduino.de

Two options: either you build a custom jig with pogo pins, or you build the circuit so that all pins are exposed somehow. You also need to make sure that anything connected to the pins of the 16V8 support being driven by the programmer. I don't know about the programming algorithm and whether it drives only a subset of pins or all of them.

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BB816 Computer YouTube series

Plus during programming one of the pins gets 12V applied to it which probably won't be healthy for anything else connected to that pin.

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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?

Latching is useful for implementing output / debug registers that keep their value over time, like displaying POST codes or writing debug values. This functionality was present in the MC14495 or the TIL311 for example, it might be nice to be able to replicate it from the originals. Not a must-have for sure!

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BB816 Computer YouTube series

On mine I use a 74ACT574 to latch. Unfortunately the MC14495s could not keep up with a 6502 running at 14MHz.

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Bill

That does not surprise me. The MC14495 has 100ns and 125ns set-up and hold times requirements respectively on the LE pin at 5V

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BB816 Computer YouTube series

Awesome! Thanks Willie. I'll post back here (in a couple of months - bit between funds at the moment) once I've got a working board going with a '16v8.

Couple of reasons why I don't want to go with a microcontroller. And too be completely honest the main reason is it would be more time for yet another skill I'd have to learn. I don't want to use the Raspberry Pico because it's too big and because it needs a clean, sharp input voltage to start-up; plugging into breadboards or pin headers sometimes causes it to crash.

In the far future I might try using a PIC33 but I haven't used one in - probably - 15 years and I absolutely hated the dev environment.

_________________
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?

I learned a few things since I last posted and a PIC16 is looking a bit more suitable.

The main reason being I hadn't realised the ATF22V10 treats it's maximum 150mA current rating as target rather than a limit. So......this, running four ATF22V10s draws half an Amp. Ouch.

It's a board specifically for debugging the '816 but spot the obvious problem. No, really, don't look too deeply. It's right there.

You can also build the 7-seg display out of individual LED and drive with a CPLD. This board monitors and displays bus activities of RC2014 or RC6502.
Bill

I rather like that - and I especially like it with the modern and now affordable option of having the PCB house do the soldering of the surface mount parts.

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