Just the signal, not the noise

Hello 8bit'ers,

It's Friday, a whole four weeks have passed, and it's finally time for a new issue. Even though we had to skip a release, we've kept our eyes open in all directions and summarized the most exciting and beautiful retro projects of the past four weeks in this current issue.

For the upcoming issues, we will try to return to a bi-weekly rhythm.

But now, enjoy Issue #90.


New Apple //e Emu

New Apple //e Emulator
Imagesource: pvproductions on Freepik

Michel Pollet, aka @buserror, initially doesn't have much good to say about existing Apple //e emulators for Linux. Upon a closer look, however, he does have a point that the source of linapple is somewhat... let's say cluttered and outdated. Fair enough, nearly 25 years without a major rewrite inevitably results in a significant amount of technical debt.

And that provides a good reason for a complete rewrite. Said and done, since last month we can now admire his MII Apple //e Emulator.

The emulator can only be compiled on Linux, has minimal dependencies, is entirely written in C, is small, fast, and charming. Additionally, it comes with ROM and font files, so there's no need to worry about potentially illegal downloads. 🫣

For those interested, you can directly connect to it via Telnet, there's a debugger with a stepper available, and a mini-assembler is also on board.

Great project. I'm curious to see what the source looks like in 25 years. 😜

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CRT Shaders

CRT Shaders
Imagesource: https://github.com/DeadlyRedCube/

There's a reason why serious engagement with retro hardware and software demands an authentic CRT screen. How else are you supposed to heat your living room in these times of scarce and expensive energy (at least in our part of the world)? 🥶

But let's stick to reality. Beyond their marvelous warming capabilities, CRTs render bitmaps in an analog way, featuring a fast electron gun creating pixel by pixel including scanlines. The visual delights designed in the 80s and 90s, regardless of their form, were tailored to these effects.

Rendering games from that era on a modern monitor often leads to disappointment. Somehow, you remember the visuals being different! This is a major issue for many emulators of retro systems, and a significant challenge in maintaining the legally mandated nostalgia factor!

An unknown user, publishing on GitHub as DeadlyRedCube, has taken it upon themselves to change this. Or at least to provide a piece of software that others can use to simulate the optical effect of a CRT screen in their own projects through shaders.

Cathode-Retro is impressive. This C++ wrapper around a series of shaders simulates a color NTSC signal, achieving remarkable results.

For those currently working on a retro project in C++, this is precisely the finishing visual touch you need. And for those who have already completed their emulator... here's something for your roadmap.

Nice one!

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xa65 Update

xa65 Update
Imagesource: rawpixel.com on Freepik

Those who regularly find joy and satisfaction in creating machine code for the 65XX processor family are likely familiar with xa65.

Andre Fachat's open-source 6502 cross assembler is among the best of the best for skillfully stringing together colorful bytes in the memory of an 8-bit powerhouse.

Cameron Kaiser, at home at www.floodgap.com/, is the current maintainer of xa, and has recently released Version 2.4.0. The list of new features is quite long, and those using any UNIX-like operating system, still working with a version 2.3.x, and eager to directly face the deprecation warnings of the 2.3 version, will find themselves well-positioned with version 2.4.0.

But seriously, this piece of software is among the finest for cross-assembling for MOS6502 descendants, and dxa, a disassembler belonging to the project, has been available for some time now as well.

Enjoy the update.

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Venturing into Hardware

Venturing into Hardware
Imagesource: macrovector on Freepik

Are you more on the software side of things but the grass on the hardware side seems somewhat greener?

Who doesn't wake up in a cold sweat at night because the dream of being a true master of our craft is incomplete without hardware knowledge on their personal milestone list? (Well, not me, but I'm no benchmark. 😁)

Diego Parrilla, aka @sidecartridge, has gone through this journey, experiencing and living through all the pitfalls, blunders, challenges, and problems of hardware design. Some might know Diego from his SidecarT project, which really boosts the Atari ST, STE, and Mega with the help of a Raspberry Pi Pico.

Diego has documented his journey in great detail here. Not that the article is discouraging, but it certainly makes you think differently about diving into hardware. And that can save not just nerves and time but also a lot of money.

A great piece of reading material for all who now want to venture into hardware.

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C and 8bit Systems

C and 8Bit Systems
Imagesource: https://8bitworkshop.com/

Steven Hugg, known as @8bitworkshop, is probably a familiar name to anyone who deals more or less seriously with 8-bit systems and knows how to use Google's search bar.

Sooner or later, one inevitably comes across Steven's 8bitworkshop. Occasionally, Steven surprises with a fresh and interesting article on a topic that might not have been on your radar. This was the case recently with the subject of C compilers and 8-bit systems.

Does it even make sense? The limited address space and thus memory, the minimalistic stack, and all the other limitations of 8-bit processors make the use of a C compiler at least initially questionable.

In Problems with C and 8bits, Steven delves into these very challenges and comes to some surprising conclusions.

A great read for a few quiet minutes.

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Arithmetic in Hardware

Arithmetic in Hardware
Imagesource: https://thelast19digitsofpi.github.io/

Okay, I can piece together a half adder from a few logic gates in LogiSim from memory. A full adder is still within reach. And with a little bit of XOR, subtraction is also attainable, but for everything beyond that...

Low-level hardware design is as fascinating as it is challenging. Implementing multiplication, division, and other mathematical operations in hardware is a task that you either faced for the last time at university, or, if you decided to live off ASIC design, it's your daily bread.

But how about refreshing your knowledge in this area, just like that, and for free?

Croix Gyurek, publishing code as thelast19digitsofpi, has done a good chunk of the work for us and thankfully documented it sufficiently. In his three-part series Hardware Explorations, admittedly, there's a lot to learn. The examples are mostly interactive, calling for a hot beverage of your choice and a cozy armchair.


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Two's Complement

Two's Complement Explained
Imagesource: https://imapenguin.com/

Two's Complement is a topic that seems to resurface at least twice a year somewhere. The representation of negative integers, which can then functionally perform subtraction as addition at the binary level, is simply fascinating.

You either live with the fact that it just is that way, remember how it's done, and then promptly forget it again since you never really need it in our modern world.

Or you're among those enthusiasts who like to experiment on their own hardware (simulated or real) and delve into why negating all bits and adding 1 mathematically just works.

Michael Doornbos, aka @mrdoornbos, has recently done this, and even though we've repeatedly included explanations on the subject in our magazine, his version A gentle Introduction to Two's Complement is worth mentioning.

Need to fill a knowledge gap? Then here's your chance.

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6502 Simulator

MOS6502 Simulator
Imagesource: https://8bitnews.io/

Nearly everyone who has tinkered with a variant of the MOS6502 is familiar with Skilldrick's easy6502Nick Morgan's introduction to assembly programming is not only legendary, but it is also simply excellent. Therefore, it's not surprising that there are offshoots of the project attempting to improve on the shortcomings of the original.

Torkild Ulvøy Resheim, known as @torkildr, has done exactly this, releasing the remarkable 6502js.

Unlike Nick's version, this simulator comes with complete documentation of all the official mnemonics of the 6502 assembly dialect, including the various addressing modes.

Since there is no direct introduction to assembly programming, this small but fine tool is more suited for those who already know what they are doing or for those who want to take the next steps.

And if you have the time and interest, just load one of the 18 examples and dig through the sources instruction by instruction.

A great project.

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Adapting WozMon

Adapting WozMon
Imagesource: https://youtu.be/7M8LvMtdcgY

A few weeks ago, Ben Eater, aka @ben_eater, ported Steve Wozniak's WozMon for the Apple I to his BE6502. The details of this were showcased in a complete video on the topic.

However, the subject of input and output was missing. While the Apple I had its own hardware for this purpose, Ben's machine comes with a serial UART interface, enabling connection via a serial terminal from a modern computer.

In his latest video, Ben delves into this implementation, walking us through the necessary changes instruction by instruction.

It's fascinating to see how simple yet complex hardware was over 40 years ago. Must see!

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Pirating Games

Pirating Games
Imagesource: https://youtu.be/ockNRSt3Nsk

Software piracy was not just a big deal in the 80s. Pretty much everyone who owned one of the then-modern computing powerhouses was involved. I personally remember times when friends of friends downloaded disk images for the Amiga over days via slow modem connections to more or less known BBS, only to then realize that disk 12 had a CRC error.

The good old days. 👴

Dimitris, known as @ModernVintageG, has a similar history and beautifully summarizes his own experiences with the C64 and Amiga from that era in his current video. A piece of nostalgia for a few relaxed minutes in between.

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Amiga GFX Archive

Amiga GFX Archive
Imagesource: https://amiga.lychesis.net/

Staying with the Amiga and its graphic capabilities, what Daniel Kürsten, known as @amigagraphics, offers is a testament to this iconic machine. The Amiga, introduced at the Cebit in 1987, shone with graphic capabilities that were unmatched by nearly any competitor at the time.

Even today, more than 35 years later, there's an entire scene still actively engaging with EyeCandy on the Amiga.

Daniel has collected an incredible number of these sometimes true masterpieces and makes them available for viewing completely free of charge on his website amiga.lychesis.net.

Be warned, it's a timesink.

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Filtering retro material from four weeks is anything but a trivial task. We hope we haven't failed in this endeavor and that there was something of interest for you among the topics.

As mentioned, we will try to maintain a bi-weekly rhythm for future issues, but there are still some hurdles for which we need more of a bulldozer than a shovel... we are doing our best.

If you want to help: We are always grateful for material for upcoming issues. We are even more grateful for new subscribers. If you know someone who might enjoy our magazine, please pass it along.

Winter is setting in – at least in our latitudes, and there's finally some snow again. A good reason not to go outside, but to spend the free time in front of a monitor instead. In this spirit – build something, and speak about it.

Jan & Bastian

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