I stumbled across a new PIC chip (24FJ256DA210) that contains an embedded graphics generator, CLUT and 96K of RAM (enough for QVGA 320x240 @ 8 bpp) that looks interesting. Slightly higher resolutions and colour depths are possible if integrated with an external RAM. The graphics controller can do ...

See this lecture from an engineer at Kemet, the capacitor manufacturer: https://www.youtube.com/watch?v=ZAbOHFYRFGg

I was a repair tech at TEAC's (home audio and semi-professional tape recorders) main western hemisphere location in Montebello, CA in 1982 and '83 and fixed over a thousand units ...

Ok, I did not know I could filter by lifespan. Thank you.

I know this is a bit of a subjective question, but for my project I'm going to need a bunch of capacitors. I own a C128 and it was repaired by a previous owner due to damaged traces from leaking capacitors, and I've seen videos of others being repaired for the same reasons. I've also owned a truck ...

Cassette drives were popular in the U.K., but even then I doubt much software actually used anything specific to the drive. I used to have a Datasette, but I never recall using it, my software was all on disk.

My concern would be software modifying those bits for some reason, perhaps by not ...

I think I should have a working setup on the upper lines. Its probably not fast enough for anything more than a couple MHz because I'm limiting it to through hole type chips. I just used a bunch of NOR gates on the lines, then AND gates off those. But it should work.

Yes, I might need to redo it ...

I have not had much spare time this week. I'll probably just use a bunch of gates in dip style. Again the final build will probably use something different. I'll post a schematic when it's done.

Only dead C64s.

The Digi-Key site is primarily what I've been using. But yes, I am ignorant on the subject to a large extent. I played around with this kind of stuff back in my teenage years.

When I ran a search for a multi input OR gate on Digi-Key in the 74 AC series, it produced zero results. Now is it ...

I'll have to look at those little logic chips.

Btw, I got the lower part of my schematic redone using the 74ac138. Definitely uses a lot fewer components. I'll be able to fit more of the logic schematic on one page. And yes it's much faster. I'm trying to figure out how to get rid of the FCT521s ...

I can do surface mount in the final build. But in testing and development, the ability to use DIP packages is very attractive. In surface mount parts I have to build adapter boards first.

Also keeping many parts socketed allows parts to be replaced. But if I do it right, most should never fail.

Fair enough, I'm going to find an alternative to the comparators. The 521s aren't bad, but the 85's are not nearly quick enough. It seems magnitude comparators are usually much slower. I'll look at ditching them entirely.

In regards to the LS, that was a mistake. My schematic program has templates ...

Ok, I'll look at that. I'm certainly no expert at this kind of stuff. But anything that uses fewer or cheaper chips or that has less delay is great. Switching speed is important, especially if I want to hit my full speed target.

The FCT521 was choosen because it takes a maximum of 4.5 ns to switch ...

I started this thread for sorting out the memory map logic

viewtopic.php?f=4&t=4394

Ok, here are some revisions. I'm not sure what to do with the first 521's output to keep from drawing too much current through it yet. I'll figure something out. I was thinking in terms of a driver of some sort, or a switch or something.