Search found 20 matches

by qwertykeyboard
Thu Apr 30, 2020 8:58 pm
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

I don't own an oscilloscope, so would it be useful to buy a cheap little logic analyzer like this: https://www.ebay.ca/itm/USB-Logic-Analy ... SwLSBc-btw
to do debugging and that type of stuff.
by qwertykeyboard
Thu Apr 30, 2020 6:30 am
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

It seems that TI is one of the few manufacturers that still make logic chips. Browsing Digi-Key seems to reveal that, in most cases, with the exception of Toshiba, all other major IC manufacturers have stopped making 74 series chips in DIP.

Once TI stops making these chips we're in real trouble ...
by qwertykeyboard
Thu Apr 30, 2020 2:28 am
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

The good thing is that discrete logic in PDIP packages is still plentiful and relatively inexpensive. However, it isn't going to stay that way, so a little bit of hoarding now may prove to be a wise thing to do.
I especially like this ^^^^ paragraph. You may find a price break at qty 10. Get ...
by qwertykeyboard
Wed Apr 29, 2020 11:27 pm
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

If I wanted to use another 74AC74 to divide the clock further after the output of the first 74AC74, would there be any kind of problems with this?
No. Do as many cascades stages as you want. (There are two available in a single '74 IC though).

Also I'm wondering as to why to use a 74AC74 instead ...
by qwertykeyboard
Wed Apr 29, 2020 11:14 pm
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

If I wanted to use another 74AC74 to divide the clock further after the output of the first 74AC74, would there be any kind of problems with this? Also I'm wondering as to why to use a 74AC74 instead of a 74HC74?
by qwertykeyboard
Wed Apr 29, 2020 8:00 am
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

Also with regards to clock speed, I've read the clock primer already but I'm wondering what a good clock speed would be to start off with?
I've been looking into getting a 74HC4060 and using that to divide a 32768 khz crystal if I need lower clock speeds to see whats going on data and address ...
by qwertykeyboard
Wed Apr 29, 2020 7:22 am
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

Also with regards to clock speed, I've read the clock primer already but I'm wondering what a good clock speed would be to start off with?
I've been looking into getting a 74HC4060 and using that to divide a 32768 khz crystal if I need lower clock speeds to see whats going on data and address lines ...
by qwertykeyboard
Wed Apr 29, 2020 1:08 am
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Re: Good 74HC parts to have

How many of each should I buy? Would two of each be ok?
by qwertykeyboard
Tue Apr 28, 2020 11:13 pm
Forum: Newbies
Topic: Good 74HC parts to have
Replies: 33
Views: 4842

Good 74HC parts to have

I'm about to place an order from my local electronics store and among other things, I'm looking to have a good assortment of 74hc parts to have on hand. What are some others that you guys would recommend that are useful in a 6502 computer project?
by qwertykeyboard
Wed Jul 18, 2018 12:36 am
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

Ok so I read through that manual and after the reset pin goes high after the chip powers on, it takes 6 clock cycles before it fetches the program count which happens to be EAEA, which can be seen on the 6th cycle on the 6502 I have setup. Pretty neat! :) But what is being shown on the bus before it ...
by qwertykeyboard
Tue Jul 17, 2018 8:09 pm
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

Hi, qwertykeyboard :)

it doesn't start at EAEA, but a little bit higher than that. Why is that? In fact it *does* start at $EAEA but you're not seeing that very first cycle because this procedure you're using is slightly misguided: "It does 2 clock cycles before reading off the address bus since ...
by qwertykeyboard
Tue Jul 17, 2018 4:04 pm
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

Thanks for the input everyone! Ok, so I salvaged a NMOS 6502 out of an old piece of equipment just so I can play around with it for a little bit but I intend to purchase a new WDC cmos variant later on.

So what I did is hardwired the 6502 in NOP mode and hooked A0-A6 to the data pins of my arduino ...
by qwertykeyboard
Tue Jul 17, 2018 1:00 am
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

So, I have a 6502 processor in hand. Should I try wiring up a NOP test? Also, how would I go about making a single step clock signal with any kind of de bounce so that I can observe that the address lines are counting up with led's?

With regards to the logic chips, I intend to order an assortment ...
by qwertykeyboard
Mon Jul 09, 2018 7:33 pm
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

As the local curmudgeon, the fundamental question is "What is the goal?".

Is it to get a chip to make blinking lights? A terminal connected to a monitor?

Why 8-Bit? Why not a modern micro controller?

Are you breadboarding or soldering?

There are several "minimal chip count" schematics ...
by qwertykeyboard
Mon Jul 09, 2018 6:44 pm
Forum: Newbies
Topic: Should I start with a 6502?
Replies: 39
Views: 8783

Re: Should I start with a 6502?

Now, I'm reading over the 6502 primer and having trouble understand how clock generation works. What are the different phase clocks for and how come there isn't just a single clock pin like on the Z80? Is it possible to hook up a 555 timer at a few hertz to the 6502? because the primer has no ...