01
Raspberry Pi
During development I switched from a Raspberry Pi 4 to a Raspberry Pi 5. The performance problems that prompted this change were later identified primarily as limitations of DOSBox itself and disappeared after switching to DOSBox-X. Windows 98 had also originally been intended as the entry point for the user interface. Toward the end of development, however, there were major problems with graphical output, probably caused by limitations of emulating this environment on an ARM processor. Dropping Windows 98 and Win98 games also reduced the overall performance requirements considerably. I did not go back and test whether a Raspberry Pi 4 would now provide enough performance. In my own assessment, the cooler fitted to the Raspberry Pi is clearly oversized, but I have not yet carried out any measurements to determine the cooling capacity actually required.
02
Pantasy Retro 90s PC
Pantasy created a genuinely great set here. The many details are particularly well done, including the motherboard, graphics card and floppy drive. To the best of my knowledge, Pantasy uses GoBricks pieces, which in my personal experience feel slightly higher in quality than those from market leader LEGO. The one part I was less convinced by was the Minesweeper mechanism inside the monitor. The effect is neat, but in my view not really necessary. The mechanism is also somewhat flimsy and tends to fall apart. Even before the conversion, I therefore preferred using the cardboard screen cards instead. I also found that the inside of the monitor contains a considerable mix of unrelated brick colours – something that can be seen very clearly in the conversion photos and is entirely unnecessary. This practice is often criticised, rightly so, with LEGO sets, but it also applies to this Pantasy set.
03
Display
One of the biggest challenges was finding a suitable display for the project. The problem was not only identifying a panel with the right physical dimensions, but also deciding how it should be connected. Most suitable displays use LVDS. Direct control would in principle be possible, but these panels generally still require a 12 V supply for the backlight. The alternative would have been to use the Raspberry Pi's MIPI DSI interface. The range of available panels was very limited, however, and I could not find a suitable format. A major reason was my intention to preserve the Pantasy set's original 4:3 proportions. With a suitable MIPI DSI display, the entire system could be made much more compact because both the voltage converter and the separate controller board could potentially be omitted.
Sourcing a suitable display can also be challenging. Anyone without previous experience communicating on the international market – particularly with Chinese suppliers – or buying through B2B platforms such as Alibaba may quickly run into difficulties. There is also a certain financial risk involved in international purchasing. In my case, despite a delay of several months, everything fortunately worked out in the end.
04
Raspberry Pi Power Module
As an experienced electrical engineer who works with data sheets a lot, I had some fun with the power module used here. The module is actively cooled. Shortly after switching it on, however, I noticed that unlike the Raspberry Pi fan, its tiny fan runs continuously and always at full speed. That made operation annoyingly loud. Besides considering a modification to slow the fan down, I studied the module's description and data sheet in detail. The manufacturer hints that the fan is only required at higher loads, but never defines what actually counts as a higher load. I asked the Chinese manufacturer where the limit was and what would happen if it were exceeded with the fan disconnected – whether the controller would fail, limit its output, or simply age more quickly. The answer came very quickly, but was not particularly helpful: "We don't know exactly where the limit is, and we also have no idea what happens if the module is operated above it." In the end, because the Raspberry Pi is only lightly loaded in BrickDOS, I operate the power module without its fan. I have not yet measured the Raspberry Pi's actual power consumption, however.
05
Mouse and keyboard
During development I deliberately chose wireless connections for both mouse and keyboard. It does take away a little of the retro feeling because the cables are missing, but at the same time it avoids additional cable routing and the challenges that come with it. Unfortunately, the selection of suitable wireless keyboards and mice is fairly limited. Finding a genuinely suitable keyboard for the set was particularly difficult. There are virtually no miniature keyboards with classic tall mechanical keys. I am therefore still considering a wired alternative.
06
Speaker housings
I designed the PC speaker housings using BrickLink Studio. My experience here, as with other models I have designed in the software, is that no matter how precisely you plan everything, you almost always end up placing at least a second parts order because something is missing, was forgotten, or simply does not fit quite as expected.
I conveniently ordered original LEGO bricks through BrickLink (only used LEGO is good LEGO 😉). Once you understand how the system works, it is generally straightforward to use. I have also had good experiences with alternative shops such as Brick Owl, and especially WoBrick. Shipping from WoBrick takes a few days longer, but the bricks are new and the price is usually about the same.
07
12V Power Supply 60W
The power rating of the power supply was chosen primarily based on the expected maximum consumption of the Raspberry Pi with USB peripherals, the power module, the display and the display controller. I deliberately based the calculation on the upper end of the specified power figures. In practice, roughly half the rated power would probably still be more than enough to supply all components reliably.