added a quite unsorted first version of a floppy boot loader

1 files changed, 747 insertions, 0 deletions

diff --git a/floppy/doc/yeokhengmeng.com_2018_01_make-the-486-great-again.txt b/floppy/doc/yeokhengmeng.com_2018_01_make-the-486-great-again.txt
new file mode 100644
index 0000000..bb36547
--- /dev/null
+++ b/floppy/doc/yeokhengmeng.com_2018_01_make-the-486-great-again.txt
@@ -0,0 +1,747 @@
+                                    [1]post
+
+   [2]Home [3]Aviation [4]Retrocomputing [5]Categories [6]Favourite Quotes
+       [7]About
+
+   [8]en
+   [9]English (en) [10]­ (zh)
+
+   [11]Kheng Meng profile pic
+
+Yeo Kheng Meng
+
+   Maker, Coder, Private Pilot, Retrocomputing Enthusiast
+     *
+     *
+     *
+     *
+     *
+     *
+     *
+
+[12]A Science Project: "Make the 486 Great Again!" - Modern Linux in an
+ancient PC
+
+   January 6, 2018
+
+   17 minutes read
+
+     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 [13]Geekcamp tech conference
+   in Nov 2017 during [14]my emcee role. The theoretical answer as you can
+   glean from the title of this post is the [15]486 which was first
+   released in 1989. I determined that fact from this article where
+   [16]support for the 386 was dropped in Dec 2012.
+
+   To get you interested, here is the result of my effort.
+
+   The white smudge on the screen is not the camera's fault, there is
+   really a backlight problem with my old 19" monitor.
+
+   IFRAME: [17]https://www.youtube.com/embed/4qSziR6sD8Q
+
+   You can skip to 11:39 when the boot completes.
+
+   00:00 to 00:46 - BIOS
+
+   00:46 to 11:39 - Bootup. It takes almost 11mins to bootup!
+
+   11:39 to 13:14 - System specs, IP info and ALSA mixer
+
+   13:14 to 15:00 - Playing music via Sound Blaster 16
+
+   15:00 to 17:25 - SSH while playing (stuttering) music in the
+   background. With AlsaMixer adjusting volume.
+
+   17:25 to 17:48 - Opening a webpage hosted by nginx.
+
+   18:10 to 20:13 - Git clone a repo.
+
+   20:13 to 21:13 - Using Python 3.6.3
+
+   21:13 to 21:43 - Cleanup and issue shutdown command
+
+   21:43 to End - Shutdown. It takes 5.5 mins to shutdown!
+
+   Interested in how I got a modern Linux kernel 4.14.8 (released in
+   December 2017) to run on this ancient PC? Read on!
+
+Prior work and research
+
+   Last month, I took part in a [18]Super Silly Hackathon with my teammate
+   [19]Hui Jing where we installed Damn Small Linux (DSL) on that same 486
+   PC.
+
+   I bought this machine with the original intent to play old DOS games in
+   their original glory. Anyway, we managed to play music and even host a
+   webpage! See her fantastically detailed write-up [20]here.
+
+   The version 4.4.10 of DSL we used was released in Nov 2008. It used the
+   kernel version [21]2.4.31 that was released in June 2005 which is a
+   dinosaur by today's standards.
+
+   Throughout the entire time, the question of whether the theoretical
+   answer of 486 is actually true lingered in my head. I did some research
+   and found out [22]someone actually installed Gentoo Linux with a modern
+   kernel on a 486 PC. At least someone said it was possible although he
+   did not give any hard evidence :( He advised that one should use a
+   modern PC to do the source code compilation which I'll show later.
+
+What is Gentoo Linux and why?
+
+     Gentoo Linux is a Linux distribution built using the Portage package
+     management system. Unlike a binary software distribution, the source
+     code is compiled locally according to the user's preferences and is
+     often optimized for the specific type of computer.
+
+     From [23]Gentoo's Wikipedia page
+
+   The issue with modern Linux distributions like Debian/Ubuntu/Arch is
+   that they distribute compiled binary packages. Typically this is good
+   enough as compiling every single package you want from scratch is time
+   consuming and most people ain't got the time for that.
+
+   Although the 486 is theoretically supported by the modern Linux kernel,
+   this is not true on the distribution and package level.  For example,
+   Debian has [24]dropped support for older 586 32-bit CPUs as of 2016.
+   Thus, the oldest supported x86 CPU by Debian is the 686. The
+   6th-generation x86 started with the Pentium Pro released in 1995 or its
+   more commonly known variant Pentium 2 was released in 1997.
+
+   Therefore, it is no longer possible to directly use a typical modern
+   distribution on a 486 PC. But on an atypical distribution like Gentoo
+   which requires you to compile every package, this might still be
+   possible.
+
+The hardware
+
+The ancient 486 PC: [25]IBM PS/1 Consultant 2133 19C (released in 1993)
+
+   Marvel at the original specs of this machine. The CPU and RAM were
+   fully upgraded by the seller before I bought it.
+
+Specifications:
+
+     * [26]AMD 5X86 486-clone running at 133mhz
+          + Similar performance to Pentium 75Mhz
+          + The AMD 5X86 series were the fastest 486 clones ever made
+     * Cirrus Logic VLB CL-GD5424 Graphics 512KiB VRAM
+     * 64MB [27]SIMM-72 RAM
+     * 48x IDE CD ROM Drive
+     * [28]Gotek 1.44MB floppy emulator
+     * CompactFlash-IDE adapter + 32GB Sandisk Extreme CF card
+     * 10Mbps 3Com Etherlink III [29]3c509B (ISA)
+     * [30]Sound Blaster 16 CT2950 PnP (ISA)
+
+Front panel
+
+   The 48x PATA CD-ROM drive came with the PC. I replaced the original
+   3.5" floppy drive with the [31]Gotek 1.44MB floppy emulator. This cool
+   device enables one to emulate up to 100 floppy disks based on images
+   stored in the connected USB Flash drive! I no longer need to write to
+   mechanically-failure-prone floppy disks whenever I want to transfer
+   data.
+
+Expansion slots
+
+   There are only 3 16-bit [32]ISA slots placed on the riser card in this
+   PC. It does not even have the newer but also legacy [33]PCI slots. This
+   PC is filled with 2x 32MB SIMM-72 RAM sticks. I have to admit 64MB RAM
+   is unheard of for a 486-era PC. Some people [34]online managed to go up
+   to 128MB RAM.
+
+Expansion cards
+
+   The 3 ISA slots are fully filled with the following
+
+   A [35]Sound Blaster 16 CT2950 PnP, 10Mbps 3Com Etherlink
+   III [36]3c509B,and a CompactFlash-IDE (CF-IDE) adapter. Technically the
+   CF-IDE adapter is not an ISA card. It is mounted in the expansion slot
+   to enable me to easily swap out the CF card without the hassle of
+   opening up the case. To the motherboard, the CF card is just like any
+   other hard disk.
+
+Expansion cards mounted in slots
+
+   Legacy ports galore! Note the power supply which only accepts ~115VAC.
+   I had to buy a transformer to step down the 230VAC mains in Singapore
+   to suit this PC. The CF card is conveniently replaceable at the back.
+
+Compilation machine: [37]Thinkpad T430 (released in 2012)
+
+   Compilation is a CPU-heavy process and the 486 will definitely take
+   ages to do so. To avoid this issue, we shall do the compilation on a
+   modern PC using a USB card reader then move the CF card over to the
+   ancient PC.
+
+   )
+
+Specifications:
+
+     * Intel Core i7-3520M (3.50 GHz, 4MB L3, 1333MHz FSB)
+     * Intel HD Graphics 4000
+     * 16GB DDR3 - 1600MHz
+     * Gigabit Ethernet
+     * Ultrabay DVD-RW
+     * 2x USB 3.0, 2x USB 2.0
+     * USB-CF adapter to compile on CF card
+     * SSD removed to avoid corrupting it by accident during install
+
+   This Thinkpad T430 is a 6-year-old model by today's standards but is
+   still fast enough to do the compilation of everything in a reasonable
+   amount of time (like a few hours).
+
+Linux Installation
+
+   I've documented a [38]detailed list of instructions here on what
+   commands to use to install Gentoo on this ancient PC. This post will
+   just focus on the key steps and issues I faced.
+
+Step 1: Getting the install media and initial attempt
+
+   The Gentoo x86 minimal installation CD can be [39]downloaded here still
+   supports the 486 architecture. Out of curiosity, I booted my ancient PC
+   with it to see if it is possible.
+
+   Turns out I'll get a kernel panic. It is very likely this LiveCD kernel
+   does not have the drivers needed to properly access the CD drive.
+   Anyway, I got the CD started with my modern T430.
+
+Step 2: Disk partitioning
+
+   These steps below are all done on the modern compilation PC except the
+   last step.
+
+Gentoo's proposed partitioning scheme
+
+   This is what Gentoo recommends. Since this is an ancient PC, it does
+   not use UEFI therefore there is no need for the bootloader partition.
+   Ancient PCs also have a BIOS 504MiB barrier which means they can only
+   access the first 504MiB in the disk. This can be seen in the BIOS setup
+   below:
+
+   Linux can recognise the full 32GB capacity of my CF card only after the
+   kernel and necessary drivers are loaded.
+
+Actual partitioning scheme
+
+   Modern Linux distributions don't always have a boot partition by
+   default as its contents are now placed in the root partition. Since we
+   have a 504MiB limit, we will need a small 128MB boot partition as the
+   first primary partition to store the Linux kernel and other boot files.
+
+Step 3: Install Gentoo Stage 3
+
+   Stage3 is a step unique only to the Gentoo distribution. Basically you
+   have to download a tarball containing a bare minimal binaries and
+   system directories.
+
+   You have to make sure to download the one that is named "i486". Then
+   uncompress it to form the base system.
+
+   For more information about the Gentoo Stages, you can take a look
+   [40]here.
+
+Step 4: Verify compilation parameters
+
+   Portage is the package manager used in Gentoo and we have to make sure
+   that its configuration will invoke the GCC compiler to emit packages
+   that are 486 compatible. Ensure /etc/portage/make.conf has the
+   following 486-specific options:
+CFLAGS="-O2 -march=i486 -pipe"
+CHOST="i486-pc-linux-gnu"
+MAKEOPTS="-j5" # A good choice is the number of CPU cores in the system plus 1
+USE="-kde -qt4 -qt5 ffmpeg mp3 alsa"
+
+   The USE flags are for any new packages not to include GUI support and
+   add sound support (for my demo).
+
+Step 5: Configure Linux kernel
+
+   This was a tough nut to crack and I needed countless tries to get it to
+   a workable state.  To minimise kernel size, the default menu options
+   may not enable support for ancient hardware components. However,
+   support for them are still there.
+
+   The actual list of options I chose were very long so I'll only show the
+   key ones I selected.
+
+   Must disable 64-bit kernel for obvious reasons!
+
+   486 is the oldest option in this list!
+
+   ISA support has to be enabled to use the expansion cards.
+
+   ISA Plug and Play is required for autodetecting my SB16 and 3Com NIC as
+   they are late generation ISA PnP cards.
+
+   Enable both Generic ATA support and Legacy ISA PATA support
+
+   My 3Com 3C509 NIC card is still supported!
+
+   Once done we just compile the Linux kernel!
+
+Step 6: Install Bootloader
+
+   The usual bootloader used by Linux today is [41]Grub2. I tried that but
+   it did a reboot loop whenever I tried to start the system. Online
+   research say I should use the older [42]LILO bootloader instead. LILO
+   is unsupported as of December 2015 but it is still able to load modern
+   Linux kernels.
+
+   This a snippet of the_ /etc/lilo.conf_ Lilo configuration file:
+image=/boot/vmlinuz-4.14.8-gentoo-r1
+    label=gentoo
+    read-only
+    root=/dev/sda3
+    vga=4 # This will set the VGA mode to 80x30
+
+image=/boot/vmlinuz-4.14.8-gentoo-r1
+    label=gentoo-ask-vga
+    read-only
+    root=/dev/sda3
+    vga=ask # Linux will ask you to pick the VGA mode on startup
+
+   I didn't install a GUI for obvious performance reasons so I have to
+   rely solely on text mode. I set the mode vga=4 to increase "text
+   resolution" to 80 columns x 30 rows of text. I also include a vga=ask
+   in case the first option fails.
+
+Step 7: Install additional software
+
+   Though not strictly necessary to do it right now, I felt it was better
+   to leverage on the performance of the compilation machine before moving
+   the CF card over.
+
+   If you have seen the video, I installed the latest versions (available
+   in the Portage repository) of Git, Python, nginx, ALSA and MOC (console
+   music player).
+
+Step 8: Initial bootup!
+
+   Now we power down the compilation PC and move the CF card to the
+   ancient PC for booting. Just pray and hope it works! :)
+
+Problems Faced
+
+   There were several expected and unexpected problems I faced that made
+   this project more time-consuming that it already was.
+
+Cannot boot from CD
+
+   Due to the age of the PC, the BIOS only supports booting from the
+   floppy drive or internal HDD. To boot from the CD, I used the [43]Plop
+   Boot Manager that booted off a floppy disk. This added extra
+   inconveniences when it came to using CD-ROM based utilities.
+
+   To prevent wear on the already ancient mechanical floppy drive, I used
+   the floppy disk emulator.
+
+Cannot use 80-pin PATA cable
+
+   This problem caused me a huge amount of unexpected pain!!!
+
+   Left: 80-conductor PATA cable, Right: 40-conductor PATA cable
+
+   The 80-pin cable on the left is a more modern PATA cable with extra
+   ground lines compared to the 40-pin ones. It supposedly allows the bus
+   to transmit at higher speed by eliminating crosstalk while remaining
+   backward compatible. Read [44]this for more info.
+
+   When I assembled the PC, I initially started with the 80-conductor
+   cable for the drives. I faced occasional intermittent problems. From
+   the BIOS not being able to detect the drive, to Linux halfway getting
+   disk access errors to outright disk corruption. It was hard to tell
+   then was it a software fault or hardware fault?
+
+   Here are the list of steps I did to troubleshoot:
+    1. Disconnect CD-ROM drive as primary slave
+    2. Replace the CF card as I thought it was faulty
+    3. Trying different 80-pin conductor cables
+    4. Recompiling the Linux kernel many times with different SATA/PATA
+       options in case I chose the incorrect one. This took hell a lot of
+       time.
+
+   Finally, I swapped back to the original 40-pin PATA cable that came
+   with the PC and the problems never came up. To double check my
+   assumption, I tried the other 40-pin PATA cables I have in my personal
+   stash and had no issue too.
+
+   Like WHAT THE HELL? I don't think it is a fault of the cables
+   themselves. I have dealt with many older PCs and none of them ever had
+   problems when I switched to 80-pin cables so I assumed it should not be
+   an issue at first. Probably the motherboard of this PC just does not
+   like the 80-pin cable.
+
+Tough Gentoo installation procedure
+
+   Installing Gentoo is tough and time-consuming under the best of times
+   even for modern PCs. Doing it for an ancient PC like this further adds
+   to the complexity.
+
+   To put things into perspective, this is how I would rate the relative
+   difficulty in installing the different Linux distributions
+
+   [45]Linux From Scratch > Gentoo > [46]Arch Linux > Fedora/Debian/Ubuntu
+     * Linux From Scratch: Compile every single thing from scratch. I have
+       not tried this before.
+     * Gentoo: Base system is ready. Just compile kernel, bootloader and
+       extra packages. Then configure everything manually.
+     * Arch Linux: Same as Gentoo just that everything already exists in
+       precompiled binaries.
+     * Fedora/Debian/Ubuntu: Distributions are based on point releases.
+       Configuration is largely taken care off, just configure personal
+       preferences.
+
+   This is compounded by the fact that this was the first time I installed
+   Gentoo Linux and was unfamiliar with the install steps.
+
+Long iteration cycle
+
+   Saying the ancient PC is slow is a huge understatement. It takes 11
+   minutes to boot up to the login prompt and 5.5 mins to shutdown. During
+   the lengthy startup especially, I had to dutifully observe the status
+   messages to ensure there are no issues.
+
+   If there were any issues, I have to move the CF card back to the
+   compilation PC to modify the installation or worse start the
+   installation from scratch. I did this countless times and spent many
+   hours.
+
+Faulty Power Supply Unit (PSU)
+
+   The PSU failed about 2 weeks after I wrote this post. Not unexpected
+   for an old piece of hardware. For a typical modern PC, we just get a
+   replacement! However, this PC uses the legacy [47]LPX form factor for
+   its PSU. Not only that, it does not use the modern ATX power connector.
+   It uses the [48]AT style P8/P9 connector.
+
+   LPX power supplies are not easily available this days and the ones that
+   are being sold are decades old as well.
+
+   picoPSU with ATX-AT Converter
+
+   I used 2 products to replace the LPX PSU
+    1. [49]ATX-AT P8/P9 converter with -5V output I bought on Ebay
+    2. [50]picoPSU-150-XT with 12V AC-DC power adapter
+
+   Everything is tied down to the case.
+
+   Small and neat and this power brick is 230V compatible too![/caption]
+
+   A cool LPX PSU replacement don't you think?
+
+Spectre and Meltdown
+
+   Given the age of the 486 (1989 technology), it does not support branch
+   prediction.
+
+     The 486 does not implement any form of branch prediction.
+
+     [51]Source 1: Pentium Pro and Pentium II System Architecture from
+     Google Books
+
+     When the 486 microprocessor makes a decision that results in a jump
+     to a different part of your program, there is often a delay as it
+     gathers the instructions from the new area of memory. Pentium seeks
+     to avoid this with a Branch Target Buffer (BTB). The BTB predicts
+     the results of the decision-making instructions... [52]Source 2:
+     Info World July 1993
+
+   Ironically this makes it safe from the [53]Meltdown and Spectre
+   attacks. If you want to be safe from those attacks, you can run your
+   modern software on the 486! Of course this is not looking at the big
+   picture, many other security features have been implemented on modern
+   processors since then.
+
+Concluding Remarks
+
+   Despite the many roadblocks I faced, I was impressed by the level of
+   support Linux has for ancient hardware like this. I'll not be surprised
+   if somewhere out there, there is a tester making sure that stuff still
+   works for old hardware.
+
+   Even though this involves ancient hardware, I have to admit I learned
+   quite a lot about the components used in Linux by virtue of setting up
+   Gentoo so I have some useful takeaways from this project.
+
+   You may wonder why did I title this post "A Science Project". This was
+   coined in a [54]blog post by a Microsoft software engineer Raymond Chen
+   to describe projects that fall into any of the following categories:
+    1. A feature that is really cool and challenging from a technological
+       standpoint but is overkill for the user-scenario.
+    2. Requires hardware few people have.
+    3. Trying to solve a problem that nobody really considers to be a
+       problem. You're doing it just for the Gee Whiz factor.
+
+   I believe my projects has all of these qualities.
+    1. I went through a difficult process to give an ancient PC modern
+       Linux and software features. It is overkill as no way one can do
+       any useful work on this slow PC. It is much more appropriate to
+       install a period-correct operating system like DOS and/or Win 3.x.
+    2. How many people have a 486 PC today?
+    3. Who has a problem of needing a modern OS on this ancient PC?
+
+   As mentioned earlier, if you want to replicate this project, you can
+   consult the [55]low-level detailed instructions I have documented on
+   Github.
+
+   I have related projects as well, [56]Windows 3.1 on a modern PC,
+   [57]Windows XP on a modern PC and the [58]using the Covox Speech Thing
+   with a modern pc. Everything so far involves getting old stuff to to
+   work on a modern PC, this is my first blog post that does the opposite.
+   Look out for more projects from me!
+
+Clarification:
+
+   In response to questions or comments made by readers, here are some
+   additional points I want to make
+    1.  I did not show it in the video but the 486 is not powerful enough
+       to play MP3 files in real time. It'll stutter like crazy hence I
+       stayed with WAV files.
+    2. This machine has no slot for me to add any L2 cache memory. :(
+    3. I have rebooted this machine several times before taking this
+       video. So the boot times have stabilised.
+    4. I did try to boot the Tiny Core Linux CD but it never fully loaded
+       before rebooting.
+    5. Given more time,  I could have optimised the bootup time or
+       installed a GUI. However, the objective of this project is to
+       explore the possibility of modern Linux in a 486 PC. Those are nice
+       to have but given the time (many sleepless nights and weekends
+       worth) and effort I had already spent on this project, I felt it
+       was time to stop and document my work.
+    6. 64MB RAM is not representative of 486-machines of that era. Sure I
+       agree, but this machine came with this much and I don't see any
+       benefit of reducing the RAM other than to make it "more
+       representative".
+    7. I did not go with the systemd as Gentoo by default uses init. Since
+       this is the first time I'm actually installing Gentoo, I just went
+       with the default instructions.
+    8. Ext4 is used as the main filesystem to see if it is usable on this
+       old system. I wanted as much modern features as I could. When I
+       installed Damn Small Linux during the hackathon, the installer
+       already warned us that the non-journaling Ext2 is more suitable for
+       older CPUs.
+    9. Why Linux and not BSD-based OSes? The point was to test if Linux
+       and modern software still works on the 486 as claimed. Not really
+       to make a usable PC out of it for day-to-day work. Besides,
+       according to the [59]FreeBSD's website, the minimum requirement is
+       96MB of RAM. So although FreeBSD may support 486 CPUs, I really
+       wonder what 486-era motherboard can take that amount of RAM?
+   10. Why was PCI/USB/X option enabled in the kernel configuration (thus
+       slightly slowing down boot time) even though the ancient PC does
+       not have any PCI/USB/X? This was because I had a plan of making the
+       same disk bootable and usable on my modern T430 as well should I
+       need to compile and install additional packages. Disabling PCI
+       might cause problems on my modern PC. I might just need USB on my
+       compilation PC, who knows?
+
+Presentation
+
+   I gave a talk about my project at the [60]Hackware v3.8 meetup. Here is
+   the video and the slides.
+
+   IFRAME: [61]https://www.youtube.com/embed/1dgc1oq5br8
+
+     *
+          + [62]retrocomputing
+          + [63]hacks
+     *
+          + None
+
+   Please enable JavaScript to view the [64]comments powered by Disqus.
+   [65]comments powered by Disqus
+   My First Conference Emcee Experience
+   Why I use the IBM Model M keyboard that is older than me?
+
+Recent posts
+
+[66]How do I produce my flight videos?
+
+   November 6, 2021
+
+[67]Review, usage and repair of the Framework laptop
+
+   September 21, 2021
+
+[68]Birthday 2021: Year in Review and going forward
+
+   September 5, 2021
+
+[69]My Dos and Don'ts when trying to convince the unvaccinated
+
+   August 17, 2021
+
+[70]My First Helicopter Ride
+
+   July 21, 2021 [71]See more
+
+[72]Categories
+
+     * [73]singapore25
+     * [74]hacks19
+     * [75]personal18
+     * [76]aviation14
+     * [77]politics14
+     * [78]school9
+     * [79]book-reviews8
+     * [80]retrocomputing8
+     * [81]teardowns8
+     * [82]hackathon4
+     * [83]admin3
+     * [84]product-reviews3
+     * [85]repair-kopitiam3
+     * [86]keyboards2
+     * [87]quiz2
+     * [88]dvorak1
+     * [89]flight-sim1
+     * [90]vaccination1
+
+   © 2021 YKM's Corner on the Web .
+   Theme: [91]Hugo Future Imperfect Slim
+   A [92]HTML5 UP port | Powered by [93]Hugo
+   [94]free hit counter
+
+References
+
+   Visible links:
+   1. https://yeokhengmeng.com/
+   2. https://yeokhengmeng.com/
+   3. https://yeokhengmeng.com/categories/aviation
+   4. https://yeokhengmeng.com/categories/retrocomputing
+   5. https://yeokhengmeng.com/categories/
+   6. https://yeokhengmeng.com/favourite-quotes/
+   7. https://yeokhengmeng.com/about-me/
+   8. https://yeokhengmeng.com/2018/01/make-the-486-great-again/#lang-menu
+   9. https://yeokhengmeng.com/2018/01/make-the-486-great-again/
+  10. https://yeokhengmeng.com/zh
+  11. https://yeokhengmeng.com/
+  12. https://yeokhengmeng.com/2018/01/make-the-486-great-again/
+  13. https://geekcamp.sg/
+  14. https://yeokhengmeng.com/2017/11/my-first-conference-emcee-experience/
+  15. https://en.wikipedia.org/wiki/Intel_80486
+  16. https://www.pcworld.com/article/2020196/linux-3-8-will-drop-support-for-intel-386-chips.html
+  17. https://www.youtube.com/embed/4qSziR6sD8Q
+  18. https://supersillyhackathon.sg/
+  19. https://www.chenhuijing.com/
+  20. https://www.chenhuijing.com/blog/hardware-hacks-super-silly-hackathon/
+  21. https://www.kernel.org/pub/linux/kernel/v2.4/
+  22. https://retrocomputing.stackexchange.com/a/4364
+  23. https://en.wikipedia.org/wiki/Gentoo_Linux
+  24. https://distrowatch.com/dwres.php?resource=showheadline&story=406
+  25. https://en.wikipedia.org/wiki/IBM_PS/1
+  26. https://en.wikichip.org/wiki/amd/am5x86
+  27. https://en.wikipedia.org/wiki/SIMM#72-pin_SIMMs
+  28. https://www.philscomputerlab.com/gotek-floppy-emulator.html
+  29. https://en.wikipedia.org/wiki/3Com_3c509
+  30. https://en.wikipedia.org/wiki/Sound_Blaster_16
+  31. https://www.philscomputerlab.com/gotek-floppy-emulator.html
+  32. https://en.wikipedia.org/wiki/Industry_Standard_Architecture
+  33. https://en.wikipedia.org/wiki/Conventional_PCI
+  34. http://www.vogons.org/viewtopic.php?t=28748
+  35. https://en.wikipedia.org/wiki/Sound_Blaster_16
+  36. https://en.wikipedia.org/wiki/3Com_3c509
+  37. http://www.thinkwiki.org/wiki/Category:T430
+  38. https://github.com/yeokm1/gentoo-on-486
+  39. https://www.gentoo.org/downloads/
+  40. https://wiki.gentoo.org/wiki/Stage_tarball
+  41. https://wiki.gentoo.org/wiki/GRUB2
+  42. https://en.wikipedia.org/wiki/LILO_(boot_loader)
+  43. https://www.plop.at/en/bootmanager/intro.html
+  44. http://www.pcguide.com/ref/hdd/if/ide/confCable80-c.html
+  45. http://www.linuxfromscratch.org/
+  46. https://www.archlinux.org/
+  47. http://www.pcguide.com/ref/power/sup/formLPX-c.html
+  48. https://www.computerhope.com/jargon/p/p8.htm
+  49. http://www.ebay.com.sg/itm/ATX-20-PIN-to-AT-P8-P9-CONVERTER-WITH-5V-ON-OFF-SWITCH-DUMMY-LOAD-USA-MADE/251025150787
+  50. http://www.mini-box.com/picoPSU-150-XT
+  51. https://books.google.com.sg/books?id=MLJClvCYh34C&pg=PA122&lpg=PA122&dq=486+branch+prediction&source=bl&ots=gcMvZFz2Pz&sig=FJ9fEmH426N7eoHxLupu5x2ZrdQ&hl=en&sa=X&ved=0ahUKEwi7k5aCucXYAhUHQY8KHcgACkUQ6AEILjAB#v=onepage&q=486%20branch%20prediction&f=false
+  52. https://books.google.com.sg/books?id=QzsEAAAAMBAJ&pg=PA59&lpg=PA59&dq=486+branch+prediction&source=bl&ots=LCXnhUpS83&sig=g59BBBuiCx-qM6bOjRW5mkq1Nug&hl=en&sa=X&ved=0ahUKEwi7k5aCucXYAhUHQY8KHcgACkUQ6AEIPDAD#v=onepage&q=486%20branch%20prediction&f=false
+  53. https://meltdownattack.com/
+  54. https://blogs.msdn.microsoft.com/oldnewthing/20130319-00/?p=4913
+  55. https://github.com/yeokm1/gentoo-on-486/
+  56. https://yeokhengmeng.com/2016/09/windows-for-workgroups-3-11-on-vintage-and-modern-hardware-in-2016/
+  57. https://yeokhengmeng.com/2016/04/installing-windows-xp-on-a-modern-unsupported-haswell-system-in-2016/
+  58. https://yeokhengmeng.com/2017/01/a-science-project-bringing-the-covox-speech-thing-to-2017/
+  59. https://www.freebsd.org/doc/handbook/bsdinstall-hardware.html
+  60. https://www.facebook.com/events/200105140541056/
+  61. https://www.youtube.com/embed/1dgc1oq5br8
+  62. http://yeokhengmeng.com/categories/retrocomputing
+  63. http://yeokhengmeng.com/categories/hacks
+  64. https://disqus.com/?ref_noscript
+  65. https://disqus.com/
+  66. https://yeokhengmeng.com/2021/11/how-do-i-produce-my-flight-videos/
+  67. https://yeokhengmeng.com/2021/09/review-usage-and-repair-of-the-framework-laptop/
+  68. https://yeokhengmeng.com/2021/09/birthday-2021-year-in-review-and-going-forward/
+  69. https://yeokhengmeng.com/2021/08/my-dos-and-donts-when-trying-to-convince-the-unvaccinated/
+  70. https://yeokhengmeng.com/2021/07/my-first-helicopter-ride/
+  71. https://yeokhengmeng.com/post/
+  72. https://yeokhengmeng.com/categories
+  73. https://yeokhengmeng.com/categories/singapore/
+  74. https://yeokhengmeng.com/categories/hacks/
+  75. https://yeokhengmeng.com/categories/personal/
+  76. https://yeokhengmeng.com/categories/aviation/
+  77. https://yeokhengmeng.com/categories/politics/
+  78. https://yeokhengmeng.com/categories/school/
+  79. https://yeokhengmeng.com/categories/book-reviews/
+  80. https://yeokhengmeng.com/categories/retrocomputing/
+  81. https://yeokhengmeng.com/categories/teardowns/
+  82. https://yeokhengmeng.com/categories/hackathon/
+  83. https://yeokhengmeng.com/categories/admin/
+  84. https://yeokhengmeng.com/categories/product-reviews/
+  85. https://yeokhengmeng.com/categories/repair-kopitiam/
+  86. https://yeokhengmeng.com/categories/keyboards/
+  87. https://yeokhengmeng.com/categories/quiz/
+  88. https://yeokhengmeng.com/categories/dvorak/
+  89. https://yeokhengmeng.com/categories/flight-sim/
+  90. https://yeokhengmeng.com/categories/vaccination/
+  91. https://github.com/pacollins/hugo-future-imperfect-slim
+  92. https://html5up.net/future-imperfect
+  93. https://gohugo.io/
+  94. https://statcounter.com/
+
+   Hidden links:
+  96. https://yeokhengmeng.com/2018/01/make-the-486-great-again/#site-nav
+  97. https://github.com/yeokm1
+  98. https://linkedin.com/in/yeokhengmeng
+  99. https://facebook.com/yeokhengmeng
+ 100. https://youtube.com/yeokm1
+ 101. https://instagram.com/yeokm1
+ 102. https://twitter.com/yeokm1
+ 103. https://telegram.me/yeokm1
+ 104. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-capabilities.jpg
+ 105. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/super-silly-hackathon-team486.jpg
+ 106. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-logo.png
+ 107. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-original-spec.jpg
+ 108. https://yeokhengmeng.com/2018/01/make-the-486-great-again/gentoo-486-innards-front.jpg
+ 109. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-isa-slots.jpg
+ 110. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-isa-cards.jpg
+ 111. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-innards.jpg
+ 112. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-back.jpg
+ 113. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-t430.jpg
+ 114. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-livecd-boot.jpg
+ 115. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-gentoo-default-partitioning.png
+ 116. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-bios.jpg
+ 117. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-disk-layout.png
+ 118. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-stage3.png
+ 119. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-64bit.png
+ 120. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-486.png
+ 121. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-isa.png
+ 122. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-isa-pnp.png
+ 123. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-isa-ata.png
+ 124. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-3com-support.png
+ 125. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-kernel-sb16.png
+ 126. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-ide.jpg
+ 127. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-pico-psu-at-converter.jpg
+ 128. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-pico-psu-at-converter-assembled.jpg
+ 129. https://yeokhengmeng.com/2018/01/make-the-486-great-again/images/gentoo-486-pico-psu-brick.jpg
+ 130. https://yeokhengmeng.com/2017/11/my-first-conference-emcee-experience/
+ 131. https://yeokhengmeng.com/2018/07/why-i-use-the-ibm-model-m-keyboard-that-is-older-than-me/
+ 132. https://yeokhengmeng.com/2021/11/how-do-i-produce-my-flight-videos/
+ 133. https://yeokhengmeng.com/2021/09/review-usage-and-repair-of-the-framework-laptop/
+ 134. https://yeokhengmeng.com/2021/09/birthday-2021-year-in-review-and-going-forward/
+ 135. https://yeokhengmeng.com/2021/08/my-dos-and-donts-when-trying-to-convince-the-unvaccinated/
+ 136. https://yeokhengmeng.com/2021/07/my-first-helicopter-ride/
+ 137. https://yeokhengmeng.com/2018/01/make-the-486-great-again/