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Joined: Tue Dec 31, 2013 2:01 am
Posts: 116
Location: Sacramento, CA, United States
Welcome, Sheep64. I admire your positive and prolific attitude, and I always attempt to read and ruminate on your posts from beginning to end, with mixed success. Please keep the steady flow of ideas and products coming, and know that you have at least one fan.

Last edited by barrym95838 on Tue Mar 22, 2022 3:41 pm, edited 1 time in total.

Tue Mar 22, 2022 3:12 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1745
Indeed welcome, Sheep64.

You put yourself in a select group by reading the entirety of a forum - most impressive that you can also reference things you've read!

Tue Mar 22, 2022 3:52 pm
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Joined: Sat Nov 19, 2022 7:42 pm
Posts: 10
Location: Europe/London
Hi everyone. I was born a bit too late to experience first-hand the world of 6502s and Z80s, my first exposure to computers being the Acorn Risc PCs we had in primary school, and the 486 we had at home. I remember coming across the homebrew CPU web ring as a kid in the early 2000s and being fascinated by all these weird and wonderful machines people were making. The web has changed quite a bit since then and it's nice to see the web ring is still going, and forums like this too.

I spent many years writing C for embedded systems (STM32 mostly) and doing a bit of electronics design. Also wrote quite a bit of Python on the back end and for things like test jigs. I've become a bit dismayed though with the complexity of modern software, and for me this CPU design hobby is a relief from it.

After a few failed attempts I've just got my first design working, called DIP-8. I'll make a thread about it shortly.


Fri Dec 30, 2022 1:05 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1745
Welcome Kyle!

Fri Dec 30, 2022 9:17 am
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Joined: Sun Dec 19, 2021 1:36 pm
Posts: 43
Location: Michigan USA
Hello Kyle, Welcome to the Forum. I'm looking forward to reading more about your DIP-8 project!

Sun Jan 01, 2023 11:42 pm WWW

Joined: Fri Dec 22, 2017 8:04 pm
Posts: 2
A new year, a new introduction. I'm often called JC for brevity. Started programming computers as a kid, end of the 1960's. My old-school experience, in somewhat chronological order: IBM-1130, CDC-6400, PDP-11, 6809, Z80. And on the software side: BCPL, Forth, C, Icon, Lua. Nowadays, I'm mostly working in C++ and Python on STM32 and MacOS (as a full-time hobby). I've dabbled a lot in electronics, mostly digital µC stuff, and built several retro-computers - from kits and my own designs. I'm a starter, not a finisher, so there are an infinite number of loose ends around my lab / playground. I'm interested in spanning the huge variety of computing technologies we have nowadays, from signal acquisition and logic gates to garbage-collected high-level languages and dataflow computing (not to mention neural nets and AI). Yep ... all of it (hence the loose ends).

Anyway. I've hooked up an iCE40 FPGA board from Olimex to an F723-Discovery board from STM, and find this setup fascinating in the range of things one can potentially do with this. The big hurdle for me right now is to get something non-trivial going with FPGA fabric. Beyond counting LEDs and generating a static VGA image, that is. For starters, perhaps a small CPU core to run SRAM memory tests? Even generating UART output is taxing my skills at the moment, a humbling experience for a software-oriented guy. I suppose part of the struggle is finding a good simulation / emulation context for this sort of development.

I've been reading posts on this forum lately, but there's a bit much to go through it all. I'd very much appreciate some tips to overcome these beginner's hurdles ...

Jean-Claude Wippler

Wed Jan 04, 2023 5:05 pm WWW

Joined: Wed Nov 20, 2019 12:56 pm
Posts: 92

jcw wrote:
I'm a starter, not a finisher, so there are an infinite number of loose ends around my lab / playground.

I can totally relate to that. <looks guiltily around the graveyard of half-finished projects!>

I suppose part of the struggle is finding a good simulation / emulation context for this sort of development.

Verilator and Icarus Verilog are both very well worth exploring for simulating verilog code, with the former making it very easy to integrate the simulated model within a C++ testbench.
GHDL is, likewise, a very useful VHDL simulator, and now supports synthesis well enough to be used as a plugin to the open-source toolchain, making it possible to synthesize VHDL projects with yosys / nextpnr.

Gtkwave is a nice waveform viewer, for examining the simulation results of the aforementioned tools.

Also, even though you're using a Lattice FPGA, it might be worth playing with the Xilinx toolchain "Vivado", since it has a pretty good simulator built-in. I use it if I need to simulate projects that contain both VHDL and Verilog in the same project, since the tools above aren't much help in that instance. Vivado is a *massive* download, though.

(If some simulation examples would be helpful, here's an example project which simulates my own CPU running a Dhrystone program, using GHDL: ... /dhrystone
And here's a Verilator-based project to audition a number of different DAC designs in Verilog:

Wed Jan 04, 2023 7:17 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1745
Welcome, JC! Please feel free to start an enquiry thread - either one big thread for all your adventures, or a number of individual threads. It's pretty quiet here, so your posts will be seen by everyone.

Wed Jan 04, 2023 7:19 pm

Joined: Fri Dec 22, 2017 8:04 pm
Posts: 2
Thanks for the welcomes, @robinsonb5 and @BigEd. Good to see that this forum is still alive.

I've dabbled in verilator and iverilog a bit, a few years back. Will revisit, it does look like these are still valid options. I've also played with Altera's Quartus, and (less) with Xilinx's Vivado. Getting a permanent setup of the appropriate older versions of these tools going on Linux is on my todo list (I lost my old installs).

Will post in a new thread after reading up a bit more on this forum, once my questions and plans solidify a bit further.

Wed Jan 04, 2023 7:42 pm WWW
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