Editing AMD Geode
The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then publish the changes below to finish undoing the edit.
| Latest revision | Your text | ||
| Line 1: | Line 1: | ||
[[Category:Projects]] | [[Category:Projects]] | ||
TODO: meta context | |||
TODO: video production | |||
== Introduction == | |||
== | |||
For a while I've been searching for a small computer with these requirements: | For a while I've been searching for a small computer with these requirements: | ||
| Line 18: | Line 12: | ||
*Doesn't consume too much power | *Doesn't consume too much power | ||
The use case here is to run my [[Twitch DOS Bot]] I've been developing over the years. | The use case here is to run my [[Projects/DOS Twitch Bot|DOS Twitch Bot]] I've been developing over the years. | ||
After the searching I found that there were a few systems that could approximate this: | After the searching I found that there were a few systems that could approximate this: | ||
| Line 32: | Line 26: | ||
At least, until I saw an offer on eBay: a used [https://buy.advantech.net.au/Boards-Cards/Embedded-Single-Board-Computers-3-5-Single-Board-Computers-By-Processor-AMD-G-Series-Processor/model-PCM-9375F-J0A3.htm?country=Australia&token=637787139068984110&f=AUS Advantech PCM-9375F] for only $50 AUD, which is over $400 less than new. | At least, until I saw an offer on eBay: a used [https://buy.advantech.net.au/Boards-Cards/Embedded-Single-Board-Computers-3-5-Single-Board-Computers-By-Processor-AMD-G-Series-Processor/model-PCM-9375F-J0A3.htm?country=Australia&token=637787139068984110&f=AUS Advantech PCM-9375F] for only $50 AUD, which is over $400 less than new. | ||
Why such a huge discount? Video output is broken. Which means you can't really do much with this machine | Why such a huge discount? Video output is broken. Which means you can't really do much with this machine. | ||
I bought it on Nov 07 2021 and received it on Nov 12. | |||
I bought it on | |||
== Board specifications == | == Board specifications == | ||
| Line 47: | Line 39: | ||
* CompactFlash storage | * CompactFlash storage | ||
* 3 RS-232 serial interfaces (only the main serial interface is given a port) | * 3 RS-232 serial interfaces (only the main serial interface is given a port) | ||
* 8 GPIO pins (you don't | * 8 GPIO pins | ||
This at minimum would let me run by Internet-connected DOS bot and talk to DOS over a serial port. | |||
I've also not had an x86 board with GPIO before, so that seems like something fun to play with. | |||
TODO: Look at board again and validate and clarify these specifications. | |||
TODO: Include some photos of the board. | |||
== Troubleshooting == | |||
The eBay page listed the issue as "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" which sounds like it could be anything. | |||
It's a little difficult to tell what's wrong with an x86 computer without video output, so I just checked what I could. | |||
=== Power supply === | |||
Connecting the board's 5V rail to my Gophert NPS-1601 power supply caused it to draw up to 1A of current then beep. | |||
There were no short circuits or smoke. I'm assuming the beeping is from the board POSTing. | |||
Looking at the voltage drop with an oscilloscope, there was jitter from current consumption but no huge drops that would cause a brownout. | |||
=== Video output === | |||
Video output caused both my monitors to display a 'Input not supported' message twice during boot: | |||
* The first was quick just after boot and lasted a second or so, followed by a second of nothing | |||
* The second message lasts until you reset the board or pull power | |||
This is different to a 'No input' message, so some signal must be generated that the monitor can recognize but still give a failure for. | |||
=== RAM === | |||
In case some memory error was causing the machine to hang during video initialization I swapped the stick with a new one. | |||
No difference at all, so I don't think anything's really wrong with the RAM. | |||
TODO: Add RAM stick values here | |||
=== Serial output === | |||
I connected both a makeshift and proper null modem cable to the serial port on the device. There was no output on it, but my oscilloscope showed the transmit line being held low. | |||
This doesn't mean necessarily mean anything, most BIOSes on consumer hardware (old and modern) don't output on the serial port. This is horrible on many levels ranging from accessibility to troubleshooting or just configuring things if you don't have a monitor. | |||
=== Clock battery === | |||
I removed the clock battery and checked it with my multimeter. It was around 200mV, much lower than the 3V it should provide. | |||
I figured this may have caused some kind of undervoltage data corruption, but booting without the battery doesn't do anything. | |||
The battery is a Rayovac BR1632 (see [https://www.rayovac.com/wp-content/uploads/2021/08/R6099_OEMReferenceGuide.pdf Rayovac 6099 OEM Reference Guide] for more details) coin battery. This is a size smaller than the standard 2032 battery you'd see in a computer so I haven't replaced it yet. | |||
Visual inspection doesn't show any battery leakage on the battery, and I can't really check under the battery holder without de-soldering it. I'm going to assume there wasn't any damage from a leakage event. | |||
=== Keyboard === | |||
I plugged in a standard PS/2 keyboard | |||
... | |||
== | === Ethernet === | ||
... | |||
=== BIOS === | |||
I removed the BIOS chip to see how this would affect | |||
... | |||