Tom's Tech Blog

Category: Prototyping

  • Sun Blade 100 – Alive

    I’ve had a Sun Blade 100 server sitting in storage awaiting time for me to take a look sometime on a weekend or after work. The system would power up, but then drop to the EEPROM prompt with the infamous IDPROM checksum error. After a little research, I found several sites with examples of how to rewrite the eeprom. I had remembered during a JMCIS/JOTS class I had taken in the Navy that you could do all kinds of good and bad from aborting the boot process. This can be done by pressing Stop-A which drops you to an OK prompt in OpenBoot. This gives you access to a powerful Fourth language interpreter. What can be done from her is a completely other subject for another time.

    For those of you who are stuck with a non-bootable system caused by this checksum error, it may have something to do with the battery. There is an on-board CR2032 battery that can be easily replaced by opening the case. Also found within the case is the PROM chip U13, which will have a MAC address printed on top of it.

    Whether you install the battery or not, you will still need to get the prom values restored and checksummed, otherwise your system may not work as you are wanting it to.

    Several of the articles I read had comments referring back to a GitHub site that was created just for this reason by MrSparc1 found here. This site really has all you need to know to figure out how to restore your system.

    Also, I found the Oracle OpenBoot 4.x2 manual indispensable for figuring out what the heck I was typing and learning about using the stack for generating checksums with xor. You can find that here.

    Last but not least, I created my own calculator3 based on the above resources that is attached here as an Excel Spreadsheet. You can plug in your EEPROM base memory address and adjust the DeviceID, if needed. It will generate copy/paste lines you can use in the Serial CLI. A small hint, you may need to use the ‘ttya io’ to redirect Input and Output to the Serial port (9600-N-8-1 with crossover cable). Found this in the OpenBoot 4.x manual on page 79.

    Here are my references:

    1. https://github.com/MrSparc/idprom-repair/blob/master/README.md – MrSparc’s GitHub repo. ↩︎
    2. https://docs.oracle.com/cd/E19253-01/816-1177-10/816-1177-10.pdf – Oracle OpenBoot 4.x manual. ↩︎
    3. SunBlade 100 Reset IDPROM Public – My Excel Calculator that generates the commands. ↩︎

  • Ben Eater / Dawid Buchwald Clock Module

    I’ve been so intrigued with the Ben Eater breadboard clock module. One of my desires was to build a more permanent version of this for longer term use. The design I ended up landing on was the Dawid Buchwald designed circuit board based on Ben Eaters design with some modifications. There were an extensive number of files available on GitHub with the Hardware (Schematics, Gerber files, BOM, etc) as well as the software/firmware to use, if you so desire. He has made the designs available via PCBWay as well as providing links to the spec sheets and a pre-built configuration on PCBWay. As always, thanks for both Ben and Dawid for such great designs!

    Clock Module blank from PCBWay
    Clock Module partially populated

  • New Prototype Computer

    Technology progress has merely provided us with more efficient means for going backwards

    -Aldous Huxley

    Today I chronicle my progress in designing a new computer. My initial idea was to recreate the world of the computers I worked on in the Navy. These were the AN/UYK-7 and AN/UYK-20 computers. These computers were from the days when you didn’t have HDMI, VGA, or even graphics for that matter. They had blinking LED’s on the fronts of them, and their process and execution could be carefully controlled with variable speed, registers, and breakpoints.

    To begin with, my computer needed to recapture some of those basic elements such as lit button indicators, register and timing select switches, and more switches. But as I’ve dug into the actual development of something similar, I’ve been reminded how many things I’ve either forgotten or have become faint memories in need of a refresh.

    As a result of this, I’ve gone back to breadboarding and prototyping smaller concepts to avoid making any large mistakes. I’ve read many stories of grand ideas to recreate a computer, only to be abandoned due to a critical flaw that was impossible to fix.

    Here is where I will document my progress and my findings. If everything goes well, I will have a working computer that meets or exceeds my goals. If not, then we will try until we obtain a resolution.

    I’d be remiss to not mention all of the information and enthusiasm that Ben Eater has provided on the web. For those who do not know, he has provided the means (and packaged materials) to creating your own breadboard computer, both around a WDC 65C02 processor as well as a discretely wired version that is utterly amazing. Thank you Ben for putting so much into the community!