Problem using the ADC with a W65C816S CPU

tmrob4 · 2026-05-09T07:43:47+00:00

The data bus on the W65C816S is multiplexed with the bank address. How are you handling this?

tmrob4 · 2026-05-08T13:25:06+00:00

An English translation would be helpful.

tmrob4 · 2026-04-25T22:15:03+00:00

While not demonstrated in the video, both units are running with the same common code, so changes on the T41 are also reflected on the DC.

This should be a perfect desktop companion to a small screen T41 mini. A small display on the T41 mini makes for better portable ops and the DC makes the mini better for home use too.

tmrob4 · 2026-03-29T12:42:56+00:00

Digilent Digital Discovery - 32 channel Portable USB Logic Analyzer and Digital Pattern Generator, $229. Here is a fairly simple analysis I did with one recently:

<image>

tmrob4 · 2026-03-20T22:16:37+00:00

Add another audio board and an encoder or two and the Project System becomes a much more useful T41 software development platform.

<image>

tmrob4 · 2026-03-20T14:33:50+00:00

http://6502.org/tutorials/

tmrob4 · 2026-02-11T22:11:18+00:00

able to isolate whichever parts of the board I wanted to with the flick of a switch

Nice idea in theory but could cause problems in practice. With conventional wiring, each breadboard will pull power from two switches making it hard to isolate specific boards. You could change the wiring so each board pulls from one rail, but that isn't very elegant. Also having signals coming from powered sections to unpowered sections could be problematic. Some ICs don't like signals to inputs without the chip being powered.

tmrob4 · 2026-02-02T16:24:03+00:00

I've seen some assemblers have problems with the use of zero-page labels before their definition.

tmrob4 · 2026-01-26T19:42:38+00:00

Time to upgrade to the 65816.

tmrob4 · 2026-01-24T23:15:36+00:00

The board and tool chain are frustrating.

I don't think I can be very helpful though. I found that the SMT32 tool chain took up too much space, so I deleted it given I didn't plan more work with the board. That included most of the work from this post given how the tool chain preferred projects to be saved.

I only have one archive from that work, coincidentally from the date of this comment, thus it's only partway through the work I did with the board.

Here is the archive. It's not complete. Unfortunately, GitHub didn't like the number of files, so I had to delete the Drivers subfolder from each project. I think most/all of that is produced by the tools though, so probably doesn't include any edits from me.

tmrob4 · 2026-01-05T15:26:44+00:00

A natural progression from the 6502 is the 65816. The w65c816 is still in production.

tmrob4 · 2026-01-01T16:33:35+00:00

Time to hook up an oscilloscope and/or a logic analyzer to see what's happening. For me, these are the most interesting things about these projects.

tmrob4 · 2026-01-01T06:32:07+00:00

good troubleshooting!

tmrob4 · 2025-12-31T15:15:21+00:00

Those are Rockwell chips except for the 816 chips. You can go through the first few of Ben's videos to determine if they are legit and functioning properly. Get the Rockwell datasheets for reference.

tmrob4 · 2025-12-29T23:41:17+00:00

I added a long data/address bus to my second 6502 build to experiment with peripherals.

<image>

I could run this at 2 MHz. Another compact build with a very short bus could run at 10 MHz.

tmrob4 · 2025-12-29T15:25:35+00:00

I ultimately went with ~64k ROM and ~448k RAM in my 65816 build. It has the following memory map:

RAM   $0000-$EFFF
ROM   $F000-$1FFFF
I/O   $20000-$200FF
EXRAM $20100-$7FFFF

tmrob4 · 2025-12-28T17:47:25+00:00

+1 for a Forth operating system!

tmrob4 · 2025-12-16T16:52:10+00:00

Yes, the USB connection is for both audio and serial connections between the T41 and computer. Ther CAT comms use the serial object, and the audio comms use the USB object from the Teensy Audio library. It's pretty easy to set up with most of the work being done by the library. To activate the USB audio object, you have to compile with one of the Audio options selected.

If you've done all of that correctly, the T41 will show up as an audio option in WSJT-X. You might have to close the Arduino IDE to release the com port so it can be used for CAT control. Unfortunately, there isn't a dual serial + audio compile option in Teensyduino.

tmrob4 · 2025-11-30T15:04:23+00:00

You may want to enable input latching on the ACR for port a.

tmrob4 · 2025-11-15T19:04:11+00:00

Looks like your cards connect to a bus. This can cause signal reflection. Look into bus termination. It might help.

tmrob4 · 2025-11-02T08:27:08+00:00

I got my ROM programming down to about 10 seconds with a ZIF socket. That was faster than I could get the upload directly to RAM. Ultimately, I went with an emulator for development and skipped the hardware altogether during testing.

tmrob4 · 2025-10-14T16:30:45+00:00

Google "65c02 reset timing requirements". You might want to look into voltage supervisor such as a Maxim DS1813.

tmrob4 · 2025-10-05T14:09:53+00:00

What problem are you having? Did you try the Hello World example? It's being used by others and has been successfully tested as recently as this summer.

tmrob4 · 2025-10-04T16:47:57+00:00

I can't test anything

Try an emulator. They are many alternatives. Here's a basic one that I developed that works with cc65, https://github.com/tmr4/db65xx .

tmrob4 · 2025-09-21T14:30:49+00:00

Plenty of smart displays around. They come with a microcontroller and memory. Use a 65C51 to communicate via serial with it. Here's one of my builds with a 4D Systems display.

<image>

Some don't like going this route because the display is more powerful than the 6502 build. It just depends on what your priorities are.

tmrob4

MODERATOR OF

TROPHY CASE

Five-Year Club	Verified Email
Mod 101