6502 8-bit adventure

This is it, a completed build... well hardware-wise. All I need now is to concentrate on the software side. It will be quite a challenge, as I haven't programmed in assembly for 30 years.

This is my 3rd iteration of the breadboard 6502 SBC. Note that I've installed a ZIF socket for easy removal and insertion of the ROM. The top breadboard is the clock module, so I can step into the code and analyze it via the makeshift logic analyzer on the Arduino Mega. The LCD "Hello world" functions as expected. And the RTC / NVRAM has been tested and works fine.   The ACIA is not yet connected and is my next step. Of course, I will be sending a "Hello world" message to my computer via RS232 to test it out. I still have room for more IO on the PLD. Any suggestions?

When I start something interesting, I tend to overdo it. I originally contemplated using standard gates for my glue logic. But then chose to go the EEPLD (Electrically Erasable Programmable Logic Device) route. Wow, was I ambitious? Not only I was to build the 6502 single-board computer from the ground up, but I had to also get to know PLDs up close and personal at the same time. Well, it turns out it's not all that hard, if you find the right tutorials on the web, and if you have a precise memory map defined. I had this really particular memory map planned. But for my second iteration of the SBC, I opted to go simply and work my way up.  The map, for now, is 32K ROM, 16K IO space, and 16K RAM. This will change in the future. And this is the beauty of PLDs, there is no need to rewire anything. It's just the software that needs changing. I chose the ATF22V10C, a G22V10 equivalent, because of it's many input and output options: 12 dedicated inputs, and 10 configurable input/o

It turns out I had an issue with my wiring AND the breadboard power supply could not provide enough power. So I scrapped all my wiring, not trusting it, and plugged in my bench power supply as a stable source. It took all day to rewire the board with the VIA and LCD, but it was worth it... or was it. Well, it turns out I had another mystery bug. And that one was very sneaky. It took me a while to catch on, but it turns out my EEPROM chip was defective. Darn! I only have one more in stock. I need to buy a few spares, just in case. But in the end, I got my "Hello World" to print on the LCD. That was quite satisfying! PS: Before you comment on my wiring, yes, I know, it's not as neat. But I didn't want to spend too much time on it. I need to know it works, and get to the next step, the ACIA and RTC. Because as soon as I know this works, I'll either etch my own board, or go the PCBWay!

 As Perifractic would say, hello chip dippers. I worked on a version 1 of my breadboard 6502 last week. Sorry for now posting about it earlier. I opted to have some LEDs on the address and data bus for show. The hard-coded data lines 0xEA worked as expected. But as I increased the number of chips on the board, the ROM, and the RAM and the PLD (for decode logic), things started not to work so nicely. Stay tuned!

Before starting my adventure, I needed to do 2 things. Reorganize my lab space, and buy the necessary components. I wasn't quite ready to start my project, space-wise, as my office/lab was a mess and all my existing components were all thrown in various bins haphazardly.  Step one , reorder the furniture and optimize my desk space. Easier said than done, but I managed to do it in less than a day. Keep in mind that my "office" was also a dumping ground for everything else in the apartment. So I made some hard choices on what had to go and what stayed,  Mari Kondo style. It's not perfect, but it's a start. The following day, I sorted all my components, mostly because I was curious to find out what I had. And hold and behold, I had many unnecessary duplicates. That's what happens when you let me loose in my local electronics store without a shopping list or a plan. Step two , order the components needed. I chose Mouser because they carried the WD65C02 microproc

In comes the insanity!  Well, that's it! I'm not one of "those" people that reminisce and rides down memory lane in the nostalgia bandwagon. Yes, my mid-life crisis has gone and past. But I find myself wanting and yearning to have a good start in a new hobby, micro-electronics. And what better way than to start building an 8-bit microcomputer. And yes, I do dabble with microcontrollers also, so I have a good start. When I was in school in the late '80s I learned to program on the  6809  in assembly language on a single board computer (SBC). My initial thought was to recreate the aforementioned SBC, but the availability of parts is diminishing. In comes  Western Design Center , makers of the new  WD65C02  chips, still in production today.  Off the shelf components is important to my endeavor, in case I want to replicate my design. Trying to scrounge vintage and obsolete parts is not part of the plan. So, welcome to my insanity project, keep in touch, and come back