AMD Geode/Video 1/Script

This is a textual description of the video.

Introduction

My DOS Programming playlist on YouTube scrolls down the screen.

Voice: "I've been writing a DOS program for a while now"

The DOSBox-X home page scrolls down the screen.

Voice: "I've been using DOSBox but it would be nice to use real hardware"

A picture of an IBM PC XT taken by Ruben de Rijcke is shown on the screen with big green "IBM" text on it.

Voice: "Ideally I'd use an actual period accurate IBM PC"

A screenshot of expensive eBay listings scrolls past. One is shown to cost $500 AUD.

Voice: "But these are really expensive"

An eBay listing titled "Vintage Advantech PCM-9375 REV. A1 SBC Single Board Computer - AMD Geode LX800" is shown. Its status is marked as "For parts or not working, sold as-is with no guarantees." It's listed as $50 AUD.

Voice: "Checking eBay I found and industrial single-board computer for $50"

The listing description is shown. It clarifies: "For sale here is an Advantech PCM-9375 REV. A1 single board computer. Previously, I was able to boot Windows 98SE from a Compact Flash card and everything worked fine. It currently refuses to output a video signal that any of my monitors can recognise, so it's being sold as-is for parts with no guarantees. For a full spec sheet, see Advantech's site."

Voice: "The low price is just due to it's video output being broken. Most computers are designed to be useless without video output so naturally this is seen as garbage."

A receipt showing payment for the board is shown. It cost $50 AUD with free shipping. It was paid on 7 November 2021 and delivered on 12 November 21.

Voice: "I bought it anyway."

A hand is shown placing the board on a table. It is an unprotected circuit board with its chips, connectors and pin headers exposed. One large heatsink covers the CPU and another smaller heatsink covers the companion chip.

Voice: "So here it is: The PCM 9375. It stars a Geode LX800 CPU and CS5536 companion chip."

A small stick of RAM is shown.

Voice: "512 megabytes of DDR1 RAM."

An empty CompactFlash connector is shown.

Voice: "CompactFlash for storage."

The side of the board is shown with four ports: A DB9 serial port, an Ethernet port, a PS/2 keyboard port and a VGA port.

Voice: "A serial port, an Ethernet port, a PS/2 port, VGA port"

A daughterboard connected to the main board is shown, with an Ethernet port on it as well as a mini USB connector. The board is unplugged already, and pliers are used to remove it entirely.

Voice: "As well as a mini USB port and a second Ethernet port. We're just going to remove those for now while we troubleshoot."

Initial powering

A power supply with growing green LEDs flicker showing 0 volts and the word "off". Connected to it are two long bunched up wires that clip in to two pins on the board.

Voice: "The first thing I did was hook it up to a current limited power supply."

A hand is shown turning the power supply on. The camera zooms closer and shows the text jumping on the display changing to 5 volts 1 amps. The amperage jumps between 0.9 amps and 1.1 amps.

Voice: "It pulled a stable load so it wasn't completely dead on arrival."

A small lapel microphone is shown next to the board's corner. A single short beep is heard.

Voice: "It beeped. That's probably good."

A hand is shown plugging a VGA cable in to the board.

Voice: "Let's plug in a monitor and check things out then huh"

A computer monitor is shown. Grey text appears in a box with the text "Input Not Supported" slowly moving diagonally down the screen.

Voice: "And... Input not supported."

An oscilloscope probe is shown being attached to the power wire clip followed by a rapid zoom in to an oscilloscope's view.

Voice: "So I scoped the power rail."

The oscilloscope draws a flat line at 0 volts that suddenly jumps up to 5 volts and continues at 5 volts for 15 seconds.

Voice: "A major voltage drop can signal the machine isn't booting properly. I don't see that here"

The oscilloscope draws a thin line from the bottom of the screen up to 5 volts then thickens it showing around 20 millivolts of noise.

Voice: "On the other hand no drop at all could signal the machine is dead. I don't see that here either."

The camera pans to the power supply displaying 5 volts and a steady around 1.065 amps.

Voice: "Everything looks fine power wise."

RAM testing

A hand pulls out a stick of RAM and places another in.

Voice: "Bad memory can cause some weird issues so I tried another stick of RAM."

A different monitor is shown with the text "Input Not Support" appearing after a second of being blank.

Voice: "Same result. Input not support."

A hand is shown removing the RAM stick without placing another in.

Voice: "Just to confirm the RAM was actually doing something I removed it-"

The video cuts to the microphone pointed at the buzzer again.

Voice: "-and found the BIOS gave some long beeps."

A set of long beeps can be heard.

The monitor is shown again with the text "No Signal" displayed.

The board is shown with a chip marked 'V1.18' removed from its socket.

Voice: "Just to confirm this is the BIOS beeping I removed the BIOS. Everything was silent."

Battery testing

A screwdriver forcefully removing a coin battery is shown, making the battery jump across the board. A hand using pliers attempts to pick up the battery but it keeps slipping away.

Voice: "Next up I looked at the clock battery."

A multimeter is shown with its probes touching the positive and negative sides of the battery. It displays the value 198mV.

Voice: "My multimeter showed it was around 200mV. That's not good."

A close up of the battery being held by pliers is shown. The brand name RAYOVAC and the text "LITHIUM 3V BR1632 USA" is engraved on the chip.

Voice: "Perhaps a low voltage corrupted BIOS settings somehow?"

The second monitor is shown again, this time with an orange plastic frog glowing on the desk near it. The monitor still says "Input Not Support"

Voice: "Unfortunately running without the battery didn't help."

Keyboard testing

The board is shown powered in the background as a dusty and grimy keyboard comes in to frame and laid on the desk.

Voice: "At this point I wasn't even sure the machine was booting. I plugged in a keyboard and checked the machine's response."

A finger presses the caps lock key and the caps lock key light on the keyboard is shown to turn on and off.

Voice: "It handled toggling caps lock."

A finger rapidly presses the F1 key.

Voice: "It even made noises when I pressed keys."

The finger keeps pressing the F1 key but slower.

With each keypress heard a small beep can be heard in response from the computer.

Voice: "So it's doing something."

A ginger female cat is shown on the desk with only one eye. She makes a high pitched meow and moves towards the camera.

Voice: "Surprise cat visit!"

The cat jumps up on to the window sill behind the desk and looks out the window curiously.

Voice: "This is my brother's ginger cat. While we take a cat break let's talk about my sponsor for this video."

The cat peers out the window then jumps back down on to the desk to leave the room.

Voice: "Just kidding, I wanted to fill in time to show off the cat. Ok back to troubleshooting."

Ethernet testing

A hand plugs an Ethernet cable in to the board. After a second or two a green light on the port lights up.

Voice: "I plugged in an Ethernet cable. Maybe if the machine was booting over the network I'd see some packets."

Wireshark is shown on a computer monitor. The only incoming packets come from fe80::250:b6ff:fe1d:d419.

A terminal is shown on the monitor. It lists the machine's IP address on enp2s0f0u4 as the IP from before.

Voice: "There are packets but they're from my machine. So not very helpful."