Addressing memory banks?

[tuFFo126]

I wanted to ask how exactly memory banks are supported in ZX Sizif 512k. I understand that memory up to 128k via the &7ffd port as in ZX128k and I found it. How are banks handled via the &dffd port, the rest of the memory, what bits do they switch and from what addressing range of the Z80 processor with and without an SD memory card? What does ROM bank switching look like for individual operating modes?

[anarsoul]

Port DFFD:

bits 0-2: selects the page (top address bits in addition to reg 7FFD)
bit 3: selects where page is mapped. 0 for C000-FFFF

If DivMMC enabled you can address only 256K, since 128K will be reserved for DivMMC.

If DivMMC is disabled you can address whole 512K, but the last page will be shared with Magic and ULAPlus

[anarsoul]

sizif started normally but lost visibility to divIDE or divmmc.

Yeah, all-RAM mode disables divmmc automap, see (it's rammap input)

https://github.com/UzixLS/zx-sizif-512/blob/master/cpld/rtl/divmmc.sv#L55

So sizif in pentagon mode supports port #1ffd like +3? Does it only work in +3e mode?

It's supported only in +3 mode, see machine == MACHINE_S3:

https://github.com/UzixLS/zx-sizif-512/blob/master/cpld/rtl/ports.sv#L42

[tuFFo126]

Is it possible to support any external interfaces in all-RAM mode?

[anarsoul]

Well, you don't have divmmc automap feature in all-RAM mode, but divmmc ports are still available.

[tuFFo126]

So is there a chance to get to divmmc from allram mode? Only by hand?

[tuFFo126]

I analyzed the memory organization of ZX Profi compared to ZX Sizif 512. This is how I drew it. I tested the operation of port 0xdffd. The tests show that bit7 is inactive because only 512kB and officially there is no hires support. bit6, i.e. an additional screen from bank 06e' plugged in instead of ram02 to 0x8000, does not seem to work, activity together with bit3(0x7ffd)(I thought I managed to force it once, but I couldn't do it again). bit5 (CP/M) I don't know how to test, it probably requires BDI-ZX, bit4 replacing ROM with RAM works, bit3 (sco) works, i.e. changing the window for connecting banks ram00-31, either (0xc000) or (0x4000) hangs computer or I don't know how to use it programmatically.
Is it possible to use the screen with bank 06e' in sizif512?