I saw a post about this title, but I do not know Hungarian.
Can I ask for a translation, although this one post ?

For now build single blocks, but there is nothing to prevent them later to combine into a single project.
Are there any details, I should know about connecting to Enterprise more than one card at the same time ?
I would add information about switching memory banks, addressing external devices and what exactly are additional signals on the edge connector (EC0-EC3, /EXTC, SA0-SA2).

Thank you and do not worry. I do not know English well enough to judge you. But now I understand much more than the Hungarian
Ok, well what we have here ?
Points 2 and 8 have already included Now I'm working on the third.
The plan is to have 4 and 1, and exactly IDE with CF card reader. I don't know what means "hyper-mega-super"
Item 5. Is it safe? These computers have their years.
Points 6, 7 and 9. Easy to do, but RS-232 and DAC may be expensive. Only UART controller costs about $ 15.
Item 10. Full USB or enough RS232-to-USB converter ?
Item 11. I don't idea what is it

To sum this all-in-one must be very expensive.
Perhaps much more expensive than the Enterprise itself.
Maybe not everyone needs everything ?
I have an idea for a modular and yet this version, I will hold.

what exactly are additional signals on the edge connector (EC0-EC3, /EXTC,

These are the external color inputs for the Nick chip. For example sprite hardware. Currently don't use anything.

SA0-SA2

These are the Slot Address lines for the planned but never released official expansion unit.
The original concept: each slot have a different slot address, and the cards use these for memory and I/O address decoding. Plug and Play from 1985
But unfortunatelly the official unit not released, and the documents also not published. Then all expansion use own fixed address decoding, and not use these signals. Only the original EXDOS card use this system. This is the reason why a lot of ICs used in the original EXDOS card.
The clone EXDOS card also using fixed addresses, and the softwares which handling directly the floppy also use the direct addresses.
My conclusion forgot these then you can make more simple EXDOS schematic.

I would like (most of Zozo's stuff, not mentioning them again (hopefully):

* SD card (well, we have the "standard" cartridge now, but if "all-in-one" let's name that way, so no need for other components to buy/use!)
* Ethernet solution, possibly something like wiznet w5300 chip (MSX/SymbOS world seems to be interested in wiznet chips as well)
* general SPI bus solution (also usable fog eg SD-card) so other SPI slave devices can be connected and used (even like MPEG audio codec IC over SPI to be able to play MP3s, the SymbOS demos on MSX use something like that, of course a Z80 can't decode MP3 in real time ..... and those ICs are not so expensive able to work in more primitive mode too, ie simple sample playback, etc - but numerous examples exist even kind of odd things with SPI)
* DAC maybe configurable to 16 bit mode as well over only 2*8? (oh, and about some "codec ICs" may do functions like plain DAC and hardware decoding MP3/vorbis/etc as well)
* even more odd idea: USB host to be able to use mass-storage class devices at least (pen drives, even HDDs with converters if some really wants, digital cameras and cell/smart phones using this protocol etc). Sometimes even sounds better than having SD card interface

I am not sure about these:

* some PS/2 (?) mouse interface? - maybe easier to do externally to be able to use PS/2 mouse and have boxsoft-like (compatible) signaling, etc
* some PS/2 (?) keyboard interface (it's a bit complex topic and no really usable solution exist still, it seems which is kinda sad in my opinion)

What I (personal opinion!) can live without:

* IDE/HDD: SD card is big enough for "retro", much more easy to handle etc
* floppy/FD: I never liked floppies
* serial/UART stuff

Personally I think network (ethernet) is even more important than SD, ie network storage then, instead of SD card which should be swapped between EP and the PC all the time Especially if some wants to develop something with rapid testing cycles.

And BTW, a PCB between Z80 and its socket so we can "convert" I/O port accesses. For example real Spectrum emulator, not with the NMI-when-keyboard etc. Ok, this is another topic already

At what address I/O set the registry permission to write to flash ?
Or directly without any protection by /WR signal ?

WD1772-PH 02-02 is on board
My EXDOS in version for FlexiBridge.

Or directly without any protection by /WR signal ?

Just directly. Flash chips have a built in protocols for the protection. But possible add WR jumper for maximum safe.
AMD or Macronix 29F040 chips recommended, these are well tested with Enterprise.

* even more odd idea: USB host to be able to use mass-storage class devices at least (pen drives, even HDDs with converters if some really wants, digital cameras and cell/smart phones using this protocol etc). Sometimes even sounds better than having SD card interface

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Personally I think network (ethernet) is even more important than SD, ie network storage then, instead of SD card which should be swapped between EP and the PC all the time Especially if some wants to develop something with rapid testing cycles.

I have an All-in-One solution for the Spectrum that uses a USB host cable (Spectrum-PC link) for storage and also for networking(basic FTP) to the World of Spectrum web page. Who doesn't have a modern computer at the side of the Enterprise?

Yes, a great but complicate thing......