Hey thanks for the comments!
I should probably feel lucky that this thread hasn't exploded yet, but once Hackaday picks it back up it probably will.
My original V74 thread here went over the top a few times...
http://forum.6502.org/viewtopic.php?f=4&t=3329&sid=bf93658bb128b01314bd32ccaba3dffa
128,000 views, which completely surprised me actually. Must still be some interest in the old iron!
Now that farming has taken my time, V74 is on vacation until this fall, but then I intend to keep it evolving as planned.
I am very close to laying down the video system, which will be my most complex and powerful one to date (it if works)!
I look forward to seeing your work, hope you start a thread for it right here in "Tech Talk". Yours would be the first besides this one.
Here are some answers to your questions...
1) I get almost everything from Digikey or Mouser. What you want is a clock oscillator IC unless you intend to roll your own oscillator circuit.
This is the type I use on all of my video based projects...
https://www.digikey.ca/product-detail/en/cts-frequency-controls/MXO45HS-3C-14M31818/CTX752-ND/1801867
These are rock solid, and will not drift. Can be used to clock TTL or CMOS, and also available in 3.3v.
2) I have several similar books, and when I do something "proper", I follow the rules and guidelines of such wisdom.
Having said that, I break all of the rules in my own lab, especially with these massive high speed boards.
No doubt, you have heard what I have... nothing over 1MHz ever works on a breadboard.
False!
There are things you can do to make your life easier on a breadboard, such as placing subsystems together, keeping paired all bus lines the same length, and knowing all worst case propagation delays for all of your ICs. I read the propagation delay parameters before anything else on the datasheet. When you run too close the bleeding edge of acceptable propagation, rethink your circuit, perhaps with a 74HC574 data register in there to realign all signals on the next clock cycle. I do that a lot as well.
Crosstalk isn't so bad usually, and ground bounce or reflections can be kept under control by planning your IC city carefully. HC logic is a good choice because it has a slow slew rate and ringing is minimal. Add even one 74AC gate though, and you are up the creek!
That massive board of mine works great, and the original V74 was running at 40MHz without any problems at all. It actually pulled 640x480 VGA in the first version.
3) I only own a basic oscilloscope.
If something fails, I prefer to look at it and figure out why rather than letting a tool do it for me. I have learned most of what I know that way.
I have never owned or used a hardware or software debugger for any project, not microcontroller or FPGA.
if my code fails, and I really get stumped, I walk away and go sit with a pen and paper. That always does the trick!
Keep in mind that my life is based on doing as much as possible with as little as possible, so it may not be the sane way to do things!
4) 74HCT is a level translator that allows the lower voltage that TTL delivers to live well with modern HC logic.
Unless you have real TTL talking to CMOS, you only need HC logic, not HCT.
I do use HCT on my VIC-20 to FPGA project though becasue TTL is often just below the proper CMOS level.
This one also used HCT logic between the 6502 (TTL) and modern HC logic...
Another good variant is 74LVC, which will allow 5v TTL to interface with 3.3v CMOS. I am also using that on a "secret" VIC-20 project.
5) The 1/4" thick aluminum plate was just scrap, but any steel supplier could get you small pieces like that.
I cut it with a hand held angle grinder and then just drilled the holes with a hand drill.
Don't cheap out on the breadboard panels. Twin Industries all the way!
Those SRAMs were so fun to make! Did them when I had the flu and had to sit on the couch all day.
Hope to have them on the V74 board before the end of this year.
Cheers!
Brad
