Golden Delicious (Mega IIe) on Bald Engineer

Mega IIe Supercon 2023 Talk is now Live!

Wed, 15 May 2024 13:06:13 +0000

I must extend a big “Thank You!” to Lewin Day at Hackaday for this excellent Mega IIe write-up. Accompanying the post is an archived recording of my Supercon 2023 talk. That talk is where I gave a complete overview of the Mega IIe project and showed off the final case design for the first time! This project is where I took the Mega-II chip out of an Apple IIGS and built a fully compatible Apple IIe around it—something that not even Apple ever did!

Watch this video on YouTube

Measuring Apple II CPU's Glitchy Clock

Wed, 20 Mar 2024 17:58:51 +0000

The Apple II’s CPU clock has jitter or a glitch. This issue is not new—it has been present since its original design in 1977! Bald Engineer uses an oscilloscope to show how often the glitch occurs and how to correlate that jitter to its source—which is useful when you are not testing 40-year-old devices. The device under test (DUT) in this video is the Mega IIe project. It’s a fully compatible Apple IIe built around the Mega II chip.

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Mega IIe Supercon Links

Sat, 04 Nov 2023 20:56:28 +0000

These links accompany the Mega IIe presentation at Supercon 2023. Mega IIe Github Repo World’s first single-chip Apple II boots Twitch Mega IIe Livestream Archive Bit Preserve Project David Schmidt’s Tiger Learning Computer Project Pico VGA Library Social Media Links Mastodon YouTube (https://x.com/baldengineer) Facebook Bluesky Workbench Wednesdays HacksterIO Articles Live Streaming Slides PDF of the Slides (23mb) Thank You

MC1377 Measurements on Mini Apple IIe Prototype video board

Mon, 02 Aug 2021 16:17:20 +0000

Out of context screenshots are out of context On the Mini Apple IIe project, I am testing the composite/sync amplifier, which is an MC1377. The composite output looks great, until connecting the output cable to a receiver. It outputs about 2.6 Vpp until loaded with 75 ohms, then it drops to about 400 mVpp. We have replaced most of the passives on the output and have tried 3 different MC1377s. The measurements below are from a known good MC1377 removed from a working Apple IIgs.

Introducing Bit Preserve

Wed, 12 Jun 2019 18:13:01 +0000

A project I work on in my spare time is creating a portable Apple II. Like many of my projects, one leads into another. I started out wanting to make a mobile Apple II, and now I’m working on a project called Bit Preserve. How did I get from one project to the next? Well, as I looked into how to make a portable Apple II, I realized a significant issue. The original Apple II logic board has almost 80 ICs. Being a design from 1975, they are all through-hole packages. The good news is that except for the ROM chips, they are all off-the-shelf components. But such a size means it might be impossible to turn it into something handheld. I almost abandoned the project. Then, I learned about a chip included in the Apple IIgs. The name of the ASIC is “MEGA II.” (Nothing to do with Arduino.) It is a chip that integrates all of those off-the-shelf chips into an 84 pin package.

What is the Apple IIgs? - AddOhms Live Clip

Mon, 19 Nov 2018 14:04:01 +0000

During a live stream, I was asked: “What is the Apple IIgs?” In this AddOhms Live Twitch Clip, I answer the question. The Apple IIgs was the last of the highly successful Apple II line of computers. The “GS” stood for “graphics” and “sound.” Compared to previous Apple II computers, the IIgs was a fully 16-bit machine. When connected to its proprietary RGB monitor, it rendered a gorgeous display. Sadly, not much software took advantage of the improved graphics and sound capabilities. The IIgs was fully backward compatible with the older 8-bit line of Apple II computers. Its compatibility was so good that most IIgs users only used it in the compatibility mode.

Drawing Apple MEGA-II Breakout in KiCad

Thu, 01 Nov 2018 13:00:30 +0000

There is a project that has been sitting on my “to do” list for too long. My lab notebook has several dedicated pages for it. But I have not made progress. I decided to take some advice I have given to other people. When you’re stuck on starting a task, break down the project until you find a piece small enough you can get it done with no problem. The project involves the Apple IIgs. It was Apple’s last 16-bit (and 8-bit) computer. Inside are some application specific integrated circuits or ASICs that make the IIgs. The name with my attention is named “MEGA-II.” It takes all of the individual logic chips from the original Apple II design and incorporates them into a single 84-pin PLCC.