Personal Stuff

So the battery of my almost brand new (ok it is from 2012) Lenovo W530 lasted about 2 minutes when not plugged into mains power. Since the laptop is still OK I bought a replacement battery that fitted fine but the laptop greeted me with the following BIOS message.

Of course that is purely to protect me, because nobody else can make batteries like Lenovo. It has of course nothing to do with the fact that 3rd party batteries cost about 40euro and the Lenovo way over 100euro. And even if I would want to pay it, they are not available anymore.

A few years back I wrote a RISC-V core and a DVI output demo and back then I mentioned I would add extra features to both of them. The past few years I not only updated my RISC-V core, but also combined it with the DVI output core to create basically a SOC.

The RISC-V core now can run GCC compiled code, so no need for hand written assembly code anymore. There are still several key features missing, like IRQ/Trap support (which makes it impossible to run some sort of OS at the moment).

Prettige Kerst, Merry X-Mas. About 30 years ago in school I had to write one of my first C++ programs, it was supposed to print out a X-Mas tree on a green monochrome HP vt100 terminal connected to a HP-UX Unix machine.

I am not going to lie, I did have to think on how to write it again :-), and I have no idea if I wrote it like this back than in the early 90’s. Probably not, that was years before even C++98.

“Core Memory - The Basics” explained what core memory and its theory of operation is, but now it is time to actually make it work.

Next Steps

In the next part I will try to make something “useful” out of the two core memory modules I have.

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Anybody that ever did some programming on a Unix based system will be familiar with Core Dumps, but ever wondered where that name came from?

It comes from a time (1950s - 1970s) where computer stored data on ferrite cores, a lot of tiny ferrite cores. And in case something went wrong, the data stored on those tiny ferrite cores was printed, dumped, on paper to be analyzed, a core dump.

Prettige Kerst, Merry X-Mas, of course in style, by using a Digilent Nexys Video FPGA board to control a HDMI monitor.

The idea behind this mini X-Mas holiday project was to create a GPU for my RISC-V core, so it could output things on a monitor instead only turn on/off some LED’s. Since my VHDL skills are still not that great and calculating 1920x1080 pixels at 60Hz would mean FPGA clocks up to 147MHz which leave very little room for mistakes. Since I wanted it to have a bit of a C64 feeling I reduced the internal resolution from 1920x1080 to 480x270. Also I reduced the HDMI output from 1920x1080@60 to 1920x1080@30 so everything only has to run as 74MHz.

In 2020 I made a SID player based on a Lattice MachXO2 that was connected via SPI to a STM32G4 board running Zephyr.

Now I got a Trenz SMF2000 board that has a Microsemi SmartFusion2 that has a Cortex M3 and a FPGA on one chip, so connecting the CPU to the FPGA is a lot easier. Instead of going via SPI from CPU to FPGA, it is possible to use a AHB bus to connect the CPU to the FPGA fabric. The connection from the FPGA to the SID chip still needs the 5 address + 8 data + clk + cs + rw + rst = 17 pins like with the previous setup.

If you wish to make an apple pie from scratch, you must first invent the universe.

The famous quote from Carl Sagan could also be applied to computer science, if you want to make a program from scratch you must first invent the universe. Since I only had 2 weeks vacation, and inventing a whole universe would have been to much work, I skipped a few parts and started with designing a RISC-V core.

Prettige Kerst, Merry X-Mas, of course in style, by using a Xilinx FPGA to control a cheap 64x32 RGB LED matrix display.

I wrote a small program in VHDL that shift out a image to the RGB module and takes care of everything. After building it with Xilinx Vivado the resulting schematic looks like this;

Of course if this is not an example of how to do things for a real project, first of all the LED module lacks features like PWM control, current correction, over temperature protection, and simply the needed brightness compared to professional displays that are for example produced by my one of my clients. Secondly the VHDL is a bunch of n00b code, it doesn’t even have a way to control the display content, it just displays a static image. But since I am a C++ engineer by trade, learning an additional language that is very different in many ways isn’t a bad thing to do during a locked down X-Mas holiday.

After,

• Fixing the mainboard
• Refurbishing the PSU
• Installing the SCSI2SD
• Installing the GoTek drive

Finally done!

Well almost, because there where some small problems. First of all, and I wonder why I didn’t notice that before, the bottom of the case was badly warped.

So I had to take everything out again and bend the case into a bit more acceptable shape. And of course rebuild the whole thing again. After this “mechanical” problem, it was time to install the software. I already installed Workbench 2.1 on the SCSI2SD drive, but I was presented with the following screen.