Hacks on YKM's Corner on the Web

Bringing Swift to the Apple II

Thu, 25 Jun 2026 00:00:00 +0000

Swift is the modern programming language behind many apps that run on modern Apple platforms. I thought it would be nice to bring a small taste of it back to Apple’s early days, the Apple II. It was Apple’s first mass-market series of machines, initially released in 1977 with a 1 MHz MOS 6502 CPU.

I built SwiftII, a Swift-flavored mini development environment for the original Apple II to a IIe and up.

Llama 2 LLM on DOS

Tue, 15 Apr 2025 00:00:00 +0000

Ever thought of running a local Large Language Model (LLM) on a vintage PC running DOS? Now you can!

Modern 2024 PC with a vintage twist (ft. Ryzen 5 7600 & GeForce 4060 Ti)

Sun, 06 Oct 2024 00:00:00 +0000

If I were to tell you a PC has a floppy drive, optical drive, Sound Blaster card, serial, parallel and PS/2 ports running DOS, you would think I’m referring to a machine from the 1990s. But my very modern PC built in 2024 possess these characteristics!

I recently built myself a PC as my previous desktop PC was insufficient for my current needs. I decided to build one with the ability to still reach back into the past to run DOS.

In this post, I will go through my thought process I went through to decide on the specifications as well as the journey I made to run MS-DOS 6.22 on it.

DOS's Last Stand on a modern Thinkpad: X13 Gen 1 with Intel i5-10310U

Sun, 18 Aug 2024 00:00:00 +0000

When one thinks of modern technologies like Thunderbolt, 2.5 Gigabit Ethernet and modern CPUs, one would associate them with modern operating systems. How about DOS?

It might seem impossible, however I did an experiment on a relatively modern 2020 Thinkpad and found that it can still run MS-DOS 6.22. MS-DOS 6.22 is the last standalone version of DOS released by Microsoft in June 1994. This makes it 30 years old today.

I shall share the steps and challenges in locating a modern laptop capable of doing so and making the 30-year-old OS work on it with audio and networking functions. This is likely among the final generation of laptops able to run DOS natively.

My first chip with Tiny Tapeout 4 - Covox Speech Thing clone

Thu, 20 Jun 2024 00:00:00 +0000

When one thinks of designing an Application-specific Integrated Circuit (ASIC) chip, one would typically imagine a very high production cost, lack of access to tools and individuals can’t really do this unless you work in a company or academia.

Thanks to Tiny Tapeout, these barriers are broken down and I managed to have a chip that contains my own design. I sent in a very simple project but it is still my submission no less. I went through the entire submission procedure including writing a small testbench and preparing my project for submission through the very nicely documented process from Tiny Tapeout.

In this post, I will share my experience in development and demonstrating my design.

Setting up an open-frame Pentium 3 testbench

Sat, 25 May 2024 00:00:00 +0000

I have amassed a respectable collection of retro-PCs in the several years I have been engaging in my retrocomputing hobby. As part of this hobby, I regularly acquire vintage expansion cards from others. Testing these newly-acquired cards will require me to frequently disassemble my properly set up retro-machines which is a hassle to do.

To reduce the repeated handling of these old and relatively fragile setups, I decided to embark on a project to build a modular vintage PC in the form factor of an open-frame testbench. This testbench setup will facilitate testing of vintage expansion cards as well as easy evaluation of vintage operating systems.

I decided to go with a Pentium 3 (P3)-based setup similar to my Tweener setup.

In this blog post, I will go through how I set up this hardware for dual-boot between DOS 6.22/Windows for Workgroups 3.11 and Windows 98SE plus the challenges I encountered while doing so.

HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin

Sun, 10 Sep 2023 00:00:00 +0000

HDMI is a relatively modern video connector we take for granted on modern PCs and monitors. Now vintage PCs can join in the fun too with a native connection to modern HDMI monitors without any additional adapter.

(A production run has been made for this board. You can contact explit[at]mailbox[dot]org if you wish to purchase a unit.)

Building a DOS ChatGPT client in 2023

Sun, 26 Mar 2023 00:00:00 +0000

With the recent attention on ChatGPT and OpenAI’s release of their APIs, many developers have developed clients for modern platforms to talk to this super smart AI chatbot. However I’m pretty sure almost nobody has written one for a vintage platform like MS-DOS.

This client now supports Hugging Face API, Ollama API and text to speech (TTS) capability. More info on TTS is found at the later part of this post.

Building a new Win 3.1 app in 2019 Part 1: Slack client

Thu, 19 Dec 2019 00:00:00 +0000

In October 2019, my company SP Digital held an internal hackathon. My colleague Subhransu and I worked on a whacky idea of writing a brand-new Windows 3.1 app which was an OS released almost 30 years ago. The idea we chose was a Slack client. After all, Slack clients exist for most platforms but I’m certain one does not exist for Windows 3.1.

A few months later in Dec 2019, I would join the Super Silly Hackathon for the second time with fellow retrocomputing enthusiast Hui Jing. We would develop a small game for Win 3.1 with great help from the knowledge gained from this first project.

For Part 1, I shall detail the learnings and process for how a new old app can be created with the aid of modern tools and hindsight of old technologies. And perhaps what lessons can it offer us today. This blog post is a few months late as I needed time to clean up the code and write the documentation.

Don’t forget to checkout out Part 2 of the game app with Hui Jing too!

The App

Of course let’s take a look at the app.

Teardown of NDP2019 LED wristband

Sat, 03 Aug 2019 00:00:00 +0000

3 years ago, I tore down the NDP 2016 LED wristband as I got one during the Singapore National Day Parade (NDP) Preview. 3 years later, I got another one during the NDP preview held on 28 July 2019.

Board internals

Band in original condition

So time for another teardown!

A Science Project: "Make the 486 Great Again!" - Modern Linux in an ancient PC

Sat, 06 Jan 2018 00:00:00 +0000

What is the oldest x86 processor that is still supported by a modern Linux kernel in present time?

I asked the above quiz question during the Geekcamp tech conference in Nov 2017 during my emcee role. The theoretical answer as you can glean from the title of this post is the 486 which was first released in 1989. I determined that fact from this article where support for the 386 was dropped in Dec 2012.

To get you interested, here is the result of my effort.

Repair Kopitiam specialty electrical tools (Part 2): Short Circuit Limiter

Sun, 23 Jul 2017 00:00:00 +0000

If you have not read the previous post (Part 1) on this subject, I encourage you but it is not mandatory to do so before reading this post. I’ll still go through the fundamentals in this post. If you just want to see the raw technical details, the schematic and code of this project have been open-sourced here.

Post Objective

To show why did I build this and how it works plus the issues faced.

The clean case hides the complexity within.

A Science Project: Bringing the Covox Speech Thing to 2017

Mon, 02 Jan 2017 00:00:00 +0000

The Covox Speech Thing (CST) was a sound card released in 1986 by Covox, Inc to enable computers with parallel ports to have sound capability. Unlike modern machines, proper sound support was not a given on computers in that era and the Soundblaster by Creative has yet to be released.

As you will see later, the design is rather simple so I decided to revisit this old piece of hardware and see if it is possible to get it working on modern systems.

My remake of the Covox Speech Thing with a self-wrote media player software.

Video of everything in action

A Science Project: Windows for Workgroups 3.11 on vintage and modern hardware in 2016

Sat, 03 Sep 2016 00:00:00 +0000

(This is a long 5600+ words post, I recommend reading this from a tablet or computer)

Windows for Workgroups 3.11 (WFW3.11) was an operating system (OS) released by Microsoft in August 1993 and ended support in December 2001. It is part of a series of OSes released by Microsoft at that time so it is common for people to refer to it as part of Windows 3.1x (Win3.1). The specific history behind its name and version number and be found on its Wikipedia article. Here is a brief list of first-impressions I have if I were to describe this OS.

First Windows OS to have practical (installable) networking capabilities
Last one to not have a Start Menu and legacy interface before Windows 95
Last OS to require DOS as an initial install
Last 16-bit OS

Here is a teaser screenshot showing that I managed to get WFW3.11 installed on a “modern” 2009 Thinkpad T400 with networking capabilities. Recognise some familiar applications there?

(Partial) Reverse Engineering the NDP 2016 LED Wristband

Thu, 11 Aug 2016 00:00:00 +0000

(Checkout the 2019 version here!)

The Singapore National Day Parade (NDP 2016) happened on 9 August 2016 to celebrate its 51st birthday. For those who had the opportunity to attend the actual parade or its previews/rehearsals, they will also get to receive a funpack where one of the items will be a wearable LED band made by a company called Pixmob.

This band receives infrared(IR) signals from the organisers and then displays the LED colour of their choosing. There is also an onboard accelerometer. After the event when the IR signals disappear, the (single-axis I believe) accelerometer will cause the Red LED to light up when a shock is detected.

Here is the talk video on this subject I gave at Hackware v2.1.

Repair Kopitiam specialty electrical tools

Tue, 03 May 2016 00:00:00 +0000

I’m part of this voluntary social initiative called Repair Kopitiam (RK) started by the social enterprise Sustainable Living Lab. On a monthly basis, we teach Singapore residents how to repair their household electrical appliances, fabrics and furniture. Our volunteers are called repair coaches. This initiative is similar to Repair Cafes which originated in Europe. My area of speciality is of course in the electrical appliance department.

This post is however not about the intricate details of volunteering, it will be about the special electrical tools I have developed in the course of my volunteering in response to certain unique issues faced by the RK team.

A literally high-level view of the tools I developed.

Installing Windows XP on a modern unsupported (Haswell) system in 2016

Sat, 09 Apr 2016 00:00:00 +0000

(This is a long ~2900 words post, I recommend reading this from a tablet or computer)

Windows XP is the second-longest supported operating system (OS) in Microsoft’s history. Support by Microsoft finally ended on 8 April 2014 after a record-setting 12.5 years. The number one rank is technically* held by Windows 1.0 at 16 years from 1985 to 2001.

*I say “technically” as that was when Microsoft finally declared Win 1.0 obsolete but I doubt Microsoft was updating Win 1.0 during its final years. This was unlike WinXP which was updated up to its final moments and even had an emergency patch after its support ended.

This page here also puts XP’s length of support in perspective with other Microsoft OSes.

Released in October 2001, it is almost 15 years old today. I was only 11 years old when this OS was released so you can imagine I pretty much spent much of my teen years using XP machines other than Red Hat Linux of course.

Despite its age, XP continues to live on in embedded systems like ATMs, factory and medical machines where replacement costs and re-certification (timelines) makes them infeasible to be replaced in the near future. An extreme example is how the 23-year-old Windows 3.1 which crashed is still used in a French airport as of late last year.

The problem

I work in a startup called Algoaccess where we deal with medical devices specifically optician-related ones. Without going into too much detail, let’s just say we occasionally have to handle such older systems and test to make sure our product can work with them. This means we actually need a Windows XP installation for testing purposes. No, virtual machines like VirtualBox or VMWare will not cut it, we need a native installation for realistic testing.

My company could easily procure a machine of an older era with full Windows XP drivers. There are guides like this where people have used an older system to install WinXP in 2016.

But where is the fun in that? I saw this as an opportunity to determine if it is really possible to install WinXP on a much newer system. It was also a good way to relive a bit of my childhood that way.

First thoughts? It shouldn’t be that hard right? I know drivers could be an issue but it shouldn’t be a show-stopper? Turns out things are not so easy to put WinXP on modern hardware.

Eagle to DIY PCB Etching

Thu, 17 Mar 2016 00:00:00 +0000

I design Printed Circuit Boards (PCBs) as my part of my job. I also have some PCB projects outside of work with my most famous project among my peers being my PCB name card.

A major problem PCB designers like myself face is time and cost. It takes about 2 weeks (1 week if you can afford to pay much more) between the time I send a PCB design (Gerber) file to a fabricator in China to the time I receive the boards. This wait time is frustrating as my work will stall till the boards come back and I can test them. There is also a minimum order quantity of 5-10 pieces which most of the time I rarely need during the prototyping process, 1 or 2 is usually more than enough. All these including the delivery costs add up to a hefty sum as one typically has to design a few iterations before getting it right.

PCB Business/Name Card

Sat, 12 Sep 2015 00:00:00 +0000

I can’t count how many times I have received business cards only for me to forget about them shortly afterwards. I’m sure I’m not the only one that feel this way when you get a card from someone. For the technical-oriented, you can go directly to my Github link on this project.

Lets jump right into business. Here is my card:

(As with all pictures in this post, you can click to view the higher resolution versions of them.)

Front and back view of my business card as of Revision 7. All versions before Revision 6 are considered to be prototypes. The revision number can be found between the two battery holders.

First foray into wearable tech

Sun, 12 Apr 2015 00:00:00 +0000

Since I started dabbling with hardware like the Arduino, I have always wondered what it would seem like to integrate it with clothing (materials) but did not find the urge to learn.

After I joined Repair Kopitiam as a voluntary Repair Coach, I was given an apron that both distinguishes us from the participants that we are helping and protects our clothes as well. Every Repair Coach is given the liberty to personalise their apron to their liking. Some sew their names and some punch on a metal sheet etc.

So I thought why not take this opportunity to do some wearable tech and 3D print some stuff as well!

A quick video to highlight how it appears.

General Pictures

The result of more than 7 hours of labour from coding, 3D printing to sewing.

Now you see “who” is running the show. I have sewn on a small piece of cloth to act as a mini pouch for the 1000 mAh battery.

NUS Hack&Roll 2015 AAR

Mon, 26 Jan 2015 00:00:00 +0000

This is the third Hack&Roll hackathon I have joined and my very last one for this hackathon and as an NUS student. Can check out my first two here and here. Didn’t win anything but not that we were expecting any, it is the stuff we learned that were most important.

So presenting to you the Raspilizer! Done by myself and my friends Kai Yao (KY) and Yong Quan (YQ), two of my technical go-to buddies.

An independent device that does dynamic audio compression in “almost” realtime. Just feed in audio via the 3.5mm input jack and connect your speakers/headphones to the output jack!

NUS SOC Print (Android/iOS): Background, technical aspects and learning points

Fri, 26 Dec 2014 00:00:00 +0000

The apps in question are active and can be downloaded from their respective app stores.

This post is about 3000 words long as I wanted to go as in depth as much as possible to describe my experience in developing for both Android and iOS. If this length scares you already well I do not blame you, I tend to get long-winded in my reflections but I usually hope my readers learn and understand my underlying thought process behind certain decisions I made.

There should be something here for Android devs, iOS devs or people just interested to know the inner workings of my app or Sunfire.

Changing Casio watch to positive display

Thu, 24 Jul 2014 00:00:00 +0000

I recently got a new Casio Protrek triple-sensor watch. This watch model PRW3000-2 was released in 2013 featuring Casio’s new “Triple Sensor Version 3 engine” which is better than my previous fatter and heavier PAG-80. Not forgetting that it is solar-powered too meaning I will never have to change the battery in the usable lifespan of this watch! Ever since I got my PAG-80, my “OCD self” cannot live without knowing that I can measure the attitude, compass heading and temperature of the surroundings. So this PRW3000-2 is the next in the upgrade path.

I like the colour green, and the only green version available is in the negative display where the numbers are set against a dark background. Contrast that to the more typical positive display where the numbers are set against a white background like most calculators. As I did not own a watch with a negative display in the past, I thought it shouldn’t be an issue. Turns out it is HUGE one, take a look at the picture below.

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code::XtremeApps:: 2014 Hackathon AAR

Sun, 20 Jul 2014 00:00:00 +0000

This is the third hackathon I have joined and the first that involves hardware. Although my team was not selected to go for the next round of judging, I’m glad to have learned alot during this IDA-organised XtremeApps hackathon held at SMU.

My team comprising Muneer, Sathish and myself brainstormed on the first day for ideas based on the themes given. We decided to build something to help the visually-impaired identify buses when they are at the bus stop. We came up with this idea when we remembered that the visually-impaired had to stop every bus to ask the driver for the number if no one was around or constantly question the people around him. Wouldn’t it be a good thing if we could automate this tiresome process?

What I did in NUS Hack&Roll 2014

Tue, 28 Jan 2014 00:00:00 +0000

NUS Hackers tried to encourage participants to write a blog post or on social media about their experiences in the HacknRoll 2014, so here it is. Nah, I would have written this anyway without their encouragement. But after they read what I wrote, I wonder if they would still share it.

So this hackathon which was on 25-26 Jan was the second one I had attended. You can read up about my first one here. Although this time, instead of being “drafted” into a team by an acquaintance, I was the one who asked a few people if they willing to join my team.

The idea we agreed to work on was the iOS version of the SoC print app. I first started on the Android version of that app nearly one year ago. From that point up to now, several SoC friends have asked me for an iOS version. As I did not have a Mac, an iOS device or knowledge of Objective-C, there was no way for me to pick up iOS programming much less write an iOS app. Fast forward 10 months later, I’m in CS3217 with basic knowledge of Objective-C, have a Mac and a CS3217 rental iPad, I have the tools to do so now.

I have several peeves with the way this hackathon was organised compared to last year but I shall leave that to the later part of this article.

So here is my team in planning/discussion/problem solving when we were “shot”. From left, Kaiyao, myself and Yong Quan. Both of them were also the beta testers for my Android app.

Our project video. Narration was done by Yong Quan. (Try to view in HD if possible)

My experience in NUS Hack&Roll 2013

Mon, 25 Feb 2013 00:00:00 +0000

I confess I signed up for this weekend event at the last minute. One of the team members who was an acquaintance of mine said they needed one more member so I joined. I can say, I left this 24hour hackathon today with no regrets other than the proverbial, I could have done that better in hindsight attitude. This was my first hackathon and most definitely won’t be my last.

Sitting down with your team coding through the day and night then day again for only a single goal while surviving on a steady supply of snacks, soft drinks and fast food is an unforgettable experience.

My team, which I barely knew before the event but nonetheless worked reasonably well together in the end.

Number pad in DVD slot

Wed, 30 Jan 2013 00:00:00 +0000

Having switched to the Programmer Dvorak, its major shortcoming was the lower priority of the number keys. For my laptop, this was even more acute for number-intensive applications like spreadsheets. That was when I bought a number pad but I was afraid of losing it. So brainwave!

Put the number pad into the rarely-used DVD slot!

I cut the USB number pad down to size then placed it into an Ultrabay hard disk caddy. (IBM calls the DVD slot Ultrabay as it can be used by devices other than the DVD)