OK, I managed to use it. It has functions for Data cartridge but no Basic instruction. SRAM functions doesn't need RAM expansion with this firmware. I think all japanese HB-55 use this firmware only. It isn't the case for European HB-55s because it has two slot cartridges. Everything has become clear now.
I've found this dump on a Korean site and the Korean fan confirmed me that it was version 1 of HB-55, that's why I think a version 2 exists with ROMs similar to the HB-55P.
Probably this version 2 is more difficult to find, just like version 2 of HB-F500.
It was never mentioned on Japanese sites, contrary to both versions of HB-F500, so we can only guess that. The fact of missing BASIC instructions is another fact that gives more importance to this guessing.
For the rest, Sony has always confused me with its contradictory evolution. I will always prefer Panasonic approach, because they follow a logical evolution.
They are all alias names for Aackosoft. I think Manuel can explain that better than me, as he is Dutch.
For info, Generation MSX presents them as subcompanies and says that:
"Initially they used the Aackosoft brand together with Eaglesoft for budget releases, but quickly most software released was under the Eaglesoft brand. In the later years (1987-1988) they instead used the "Methodic Solutions", "Eurosoft" and "Premium III Software Distribution" brands.
There was also Aackosoft Edusystems for educational titles.
Due to the declining popularity of the MSX Aackosoft filed for bankruptcy in 1988 and re-started as Methodic Solutions, but this appears to have only given them a short respite as no software was published after 1988. There is a brief mention of this in the Dutch MS(X)-DOS Computer Magazine issue 23, page 78."
Btw, I don't see Premium (without III) mentioned in both texts...
If you look in the Eaglesoft logo, you see a big A... Looks like Eaglesoft was meant as a publishing company label. And Aackosoft was (mostly initially?) the software house. There is also "The Bytebusters", which is often mentioned as "The programmers team of Aackosoft". All very confusing, but I think it's mostly all the same company owned by Paul van Aacken and Guurt Kok.
Wasn't there a different name depending on the countries where the software was sold, for example? The Brand often changed but sometimes also the name of the software.
When i sse "copyright The The Bytebusters" and Licenced by Eaglesoft or, "Premium Software" Distribution" and presented by Eaglesoft. It's strange if the same.
Did they seek to deceive consumers, the laws, or did they have such a bad reputation that they changed their name often? This company is weird.
Here are games on tape on which it is indicated "Premium Software Distribution" (without III), "Eaglesoft" and "VA Holding" at same time:
This example gives the answer to one of your questions: Premium (without III) on the box (+ VA Holding), logo Premium III on the disk
Besides, the game itself indicates Eurosoft and it is Eurosoft that released the compilations (The Games Collections) including the same game.
As for the period Aackosoft = The Bytebusters = Eaglesoft, you can say that Premium III = VA Holding = Eurosoft, and all the names (also Methodic Solutions) are alias names of the original founding company, Aackosoft.
The official reasons behind that are unknown, we need to ask that to the founders of the company. I can only guess a special commercial strategy.
In addition of previous post: the Eurosoft logo appears also on the boxes, while the tapes you have mentioned with links display Eurosoft and VA Holding.
Aackosoft/Eurosoft are like Christian God: 1 God and 3 persons. Here, in twice + an extra joker (Methodic Solutions) due to bad situation of the company in the last year of its existence.
