In a swell foop crazyc got the P3 to boot ... the exemplary disk spiele.img boots (others at ftp://ftp.informatik.uni-stuttgart.de/pub/cm/alphatronic/p3/ have issues with copy protection that might not have been transferred into the image, people have problems saving them back to disks and booting them on the real thing).

I need some help understanding the bankdev'd memory map:

Code
static ADDRESS_MAP_START( alphatp3_map, AS_PROGRAM, 8, alphatpx_state )
	AM_RANGE(0x00000, 0x017ff) AM_READ_BANK("rom") AM_WRITE_BANK("ram_0000")  
	AM_RANGE(0x01800, 0x02fff) AM_RAMBANK("ram_1800")						  
	AM_RANGE(0x03000, 0x03bff) AM_RAM AM_SHARE("vram")						  
	AM_RANGE(0x03FF0, 0x03fff) AM_DEVREADWRITE("crtc", crt5037_device, read, write) //test hw

	AM_RANGE(0x04000, 0x0ffff) AM_RAMBANK("ram_4000")
	AM_RANGE(0x10000, 0x1ffff) AM_RAMBANK("ram")
ADDRESS_MAP_END

and

Code
WRITE8_MEMBER(alphatpx_state::bank_w)
{
	m_bankdev->set_bank(BIT(data, 6));
}

Does that mean that depending on the state of bit 6 of bank_w, either "rom" or "ram_0000" is selected?

Why is the line
Code
AM_RANGE(0x10000, 0x1ffff) AM_RAMBANK("ram")
needed, as it specifies 64K-128K RAM in a strictly 64K system?

If I omit it, MAME crashes with the error

Code
-----------------------------------------------------
Exception at EIP=000000000226b37f (memory_bank::set_base(void*)+0x000f): ACCESS VIOLATION
While attempting to read memory at 0000000000000008
-----------------------------------------------------
RAX=0000000000000000 RBX=0000000020b5b8d0 RCX=0000000000000000 RDX=000000002aaf4f50
RSI=000000002aaf4f50 RDI=00000000000012b8 RBP=000000001c308240 RSP=000000001c308220
 R8=000000000001b6b3  R9=0000000000000004 R10=000000000000000f R11=000000001c308200
R12=0000000000000000 R13=0000000000000001 R14=000000001c308790 R15=0000000004dc0168
-----------------------------------------------------
Stack crawl:
  000000001c308230: 000000000226b37f (memory_bank::set_base(void*)+0x000f)
  000000001c3082c0: 0000000000b7f67e (alphatpx_state::machine_start()+0x010e)
  000000001c308310: 0000000002264bc3 (driver_device::device_start()+0x02f3)
  000000001c308420: 000000000221c4d0 (device_t::start()+0x0090)
  000000001c3084a0: 00000000022ba992 (running_machine::start_all_devices()+0x00c2)
  000000001c3085a0: 00000000022bf44f (running_machine::start()+0x085f)
  000000001c3086a0: 00000000022c0ad0 (running_machine::run(bool)+0x0140)
  000000001c30f250: 0000000000eb1493 (mame_machine_manager::execute()+0x01e3)
  000000001c30f4f0: 0000000000f22d29 (cli_frontend::start_execution(mame_machine_manager*, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)+0x03f9)
  000000001c30f680: 0000000000f231a5 (cli_frontend::execute(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&)+0x0045)
  000000001c30f6e0: 0000000000eaf52a (emulator_info::start_frontend(emu_options&, osd_interface&, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&)+0x002a)
  000000001c30fe50: 00000000041b221d (main+0x013d)
  000000001c30ff20: 00000000004013f8 (__tmainCRTStartup+0x0248)
  000000001c30ff50: 000000000040151b (mainCRTStartup+0x001b)
  000000001c30ff80: 00007ffcc48f1fe4 (BaseThreadInitThunk+0x0014)
  000000001c30ffd0: 00007ffcc714ef91 (RtlUserThreadStart+0x0021)
Segmentation fault

How do I read the lines in machine start

Code
	membank("rom")->set_base(memregion("boot")->base());
	membank("ram_0000")->set_base(m_ram.get() + 0x0000);
	membank("ram_1800")->set_base(m_ram.get() + 0x1800);
	membank("ram_4000")->set_base(m_ram.get() + 0x4000);
	membank("ram")->set_base(m_ram.get());

Returning to the address map, can memory regions be grouped and banked in and out - the P3 swaps between 0x0000-0x3fff RAM and ROM/RAM1800/VRAM/CRTC for every access to the video memory, disk routines et al. - at the moment I think only 0x0000-0x17ff get swapped.

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