
SmartyKit Apple I replica - bdcravens
http://apple1.smartykit.org/
======
comex
The bottom photo shows an ATmega328P. So this is just a software emulation of
an Apple I? What’s the point?

~~~
jhbadger
I think it is just there for generating the video signal. This sort of thing
is common. The earlier (solder-based) Briel Replica I Apple I clone used a
Propeller chip for that. But it still had a 6502 for the actual computing, and
I imagine this does too.

~~~
erik
A lot of modern hobby computer projects use a FPGA, micro-controller, or
dedicated modern CPU to bit-bang the video signal.

How did the original 8-bit computers do it? Did they have access to chips that
are no longer produced?

~~~
duskwuff
The Apple I and Apple II both used discrete logic to generate a composite
video output. The Apple I used a couple of unusual Signetics parts (2504,
2513, 2519) and a character generator ROM to implement a text-only "video
terminal" with a UART-like interface; the Apple II used a more complex system
built around the system's DRAM refresh which allowed for graphical output.

None of this required any truly unique parts (although the Signetics parts
used in the Apple I are hard to find nowadays), but most hobbyists prefer
something more modern than composite video. :)

~~~
simcop2387
It's also a problem using discrete components for noise and EMC compliance,
you need a shielding because you have a lot more higher frequency traces
compared to otherwise. It's still possible to do without too much trouble but
compared to doing most of it in a single devices there's just very little
point in spending that much work most of the time.

~~~
duskwuff
EMC compliance isn't really a concern until you're building a consumer
product. A breadboard kit… nah. :)

Noise is a real issue -- but the main concern there is the CPU. Video
generation isn't unusually noisy.

~~~
wizardforhire
“EMC compliance isn’t really a concern”...

Unless you’re this guy

[https://hackaday.com/2019/05/15/the-great-ohio-key-fob-
myste...](https://hackaday.com/2019/05/15/the-great-ohio-key-fob-mystery-or-
honey-i-jammed-the-neighborhood/)

But seriously, you’re totally right.

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jquast
I really enjoyed building and programming on the Briel Computers Apple I
replica,
[http://www.brielcomputers.com/wordpress/?cat=17](http://www.brielcomputers.com/wordpress/?cat=17)

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randogogogo
Is anyone else seeing OpenDNS security warnings on the headlone link to the
site?

~~~
piccogabriele
yes

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randrews
I'm really curious how they're doing video. That was the big roadblock I hit
when making a Z80 computer a while ago (and what led me to FPGAs).

~~~
LeonM
The photo is low res, so can't say for sure, but I expect it uses a
microcontroller of some sorts to generate a composite video output.

~~~
randrews
That's a lot harder than it seems, so, I have my doubts. It needs to not only
run fast enough to bit-bang the signal but also simultaneously respond to bus
requests from the 6502.

~~~
phaedrus
All depends on which microcontroller it is using. The Propeller
microcontroller has multiple cores and specialized registers for video, so it
can just dedicate independent core to video and bus control. An Arduino is
certainly fast enough to bit bang video, and it could probably interleave bus
control between servicing pixels, but the code and timing for that would get
complex.

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lisper
Also worth looking at if you're into this sort of thing:

[https://www.reactivemicro.com/product/replica-1-plus-from-
br...](https://www.reactivemicro.com/product/replica-1-plus-from-briel-
computers/)

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pvg
I wonder why an Apple I? Are they perhaps concerned about IP-related problems
with the ROM and other firmware in the II? They're pretty similar but the
latter is still easily recognizable as a personal computer and the former not
so much.

~~~
zcrackerz
Wasn't the Apple I originally shipped as a kit that you had to put together? I
think it's trying to recreate that same idea, but with easier assembly.

~~~
pvg
That could be it, although I guess they also have some earlier kit that seems
to be capable of more. But maybe this can too - the 'screenshots' on that page
show things an Apple I doesn't do as it is, like display lower case letters. I
just have a hard time seeing how the end result can hold a kid's interest. An
Apple II can be made to fill the screen with rude words in a line of code!

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jasoneckert
Building, exploring, and programming the workings of early computers builds
foundation knowledge that helps with a wide variety of newer technologies.
It's good to see projects like this, in my opinion.

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crumpled
Serious question:

Do kids want to do this? Is this mainly for geeky adults.

~~~
Sendotsh
Bit of both. Kids like making things with their parents, and geeky parents are
more likely to spend the time making stuff with their kids if there’s a fun
nostalgia trip for themselves at the same time.

I’ve done a lot of retro gaming projects with my kids because I get some
nostalgia, they learn how to make things, and we all get to play some games at
the end. It’s fun for everyone.

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tyingq
Why so little information on this thing? It doesn't even mention if it's using
a real 6502, which one, etc.

