From Newsgroup: comp.emulators.apple2


Some here probably already know about this project. It is sort-of the
Apple II version of the Commodore 64 Ultimate, new hardware that
compatible ...



This homebrew Apple II skips emulation, does it all in hardware
---------------------------------------------------------------
A project has cloned the Apple II Plus, but instead of using
emulation, it goes the harder route by rebuilding Apple's classic
computer in hardware.

Image: <https://photos5.appleinsider.com/gallery/68097-143540-sbappleiicloneboak-xl.jpg>


If someone wants to get the experience of using Apple's vintage
products, they often turn to a software emulator. However, as one
project proves, it's possible to get the same effect by focusing
on the hardware side.

Posted on Sunday by Simon Boak, the SB Mini II is referred to as
a "Homebrew Apple II Clone." It is a rebuild of the Apple II Plus
from a hardware standpoint, but using modern components.
<https://unimplementedtrap.com/sb-mini-ii-apple-ii-clone/>

Boak saw that most of the basic logic chips are still available
to consumers, including the 6502 CPU. That, combined with circuit
diagrams in the original manual and a library of books on the
topic, helped Boak come up with a gameplan and a shopping list of
parts.


A modern(ized) marvel
The clone does use modernized alternatives compared to the
original design, mostly due to advancements in technology.

A key one is the replacement of the dynamic RAM (DRAM) used in the
original Apple II. While the original kept to DRAM to save on cost,
Static RAM or SRAM is also cheap enough for the project.

As a result, one and a half 32K SRAM chips are used to get the
required 48k the Apple II Plus needs. The change also means there
was no need to use circuitry to refresh the DRAM, which allowed
the memory to function.

Boak remarks that a lot of the original circuit generated a
composite video signal. Instead, using an Apple II VGA card, he was
able to get a sharper video output, as well as removing the video
generation logic from the circuitry.

In effect, it is a "headless" clone if it is used without the VGA
card.

This also helped simplify the clock and timing signals as well. In
this project, Boak uses a 4.096 MHz crystal oscillator, divided
down to 1.024MHz, which is close to the 1.023MHZ of the original
machine.

A Raspberry Pi Pico, which in itself is more powerful than the
Apple II Plus, is used as a way to connect a USB keyboard to the
Apple II. The Pico does generate the same parallel data signals as
the original keyboard, as well as eliminating the need to use
voltage level shifters.


Smart case
The project was finished off by being placed in a specially
created case, which was 3D printed in parts before being glued and
painted together. Those part files have since been released via
GitHub.

It's based on the design of the Apple ProFile hard drive. However,
there are extra vents and a rear panel added so that connections
could be accessed.

Just as the original was designed for easy access to the internals,
the enclosure's lid clips shut, so it can be opened without tools.

To go with the clone, Boak has also designed a matching Studio II
LCD monitor.

This is far from Boak's first attempt at making clones of Apple
products. In June 2024, he created an Apple 1 clone with a printer,
which used an SD card for storage.

The Apple II Plus recreation is certainly impressive, since it's a
hardware recreation instead of just using an emulator. But
sometimes, even those efforts can be just as astounding.

In 2024, a Hackintosh project aimed to recreate the original
Macintosh Plus, using modern components internally. However, the
effort used 3D printing to produce a highly-accurate full-scale
recreation of Apple's hardware.



<https://appleinsider.com/articles/26/06/28/this-homebrew-apple-ii-skips-emulation-does-it-all-in-hardware>





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