A little information about FS-A1FM to emulate on blueMSX

[atarulum]

It is not so easy to emulate Panasonic's FS-A1FM (FDD with
1200bps Modem
integrated MSX2 machine)
FS-A1FM includes Panasonic/ASCII 08KB memory Mapper in
Slot 3-3.
But in spite of emulation of Panasonic 08KB mapper, it
doesn't work
correctly.
Because of modem's emulation with I/O register.
I attach Slot 3-1 / Slot 3-3 for FS-A1FM.
Slot 3-3 is fixed.
But the register on Slot 3-1 is variable.

Here is a little information for FS-A1FM

[FS-A1FM]
FSA1FM.ROM (firmware.rom -- 1MB) shows 16 pages repeated twice (0-F == 10-1F)
but surprisingly,
their content is a mirror of the modem utility that runs
at slot 3-1! In
that slot, there are 16KBytes of Extended ROM at
0000-3FFF, the modem
utility at 4000-5FFF using its own mapper, and ram at
6000-7FFF, along
with some I/O ports at 7FC0-7FCF (that's why the files
SLOT31-?.ROM are
each different). Switch address is 7FC4, but bits 4-7 are
always
preserved when paging, so they may have another function
related to
modem.
So which pages of slot 3-3's mapper are actually used in
that slot? At
least A8-AF are used, so you'll have to make a longer
dump. By the way,
this slot has ports similar to FS-4600's slot 3-1, though
the mapper is
Ascii 8KB. But I can't assert their exact functionality
until I analyze
the full rom.

FS-A1FM's slot 3-3 Pages 80-FF are all the same as 00-7F
except for this:
80-83, 88-8B: disconnected (all bytes FF).
84-87, 8C-8F: eight mirrors of one only 8KB ram area.
So 00-7F is enough for future emulation.

This is additional data about mapper structure of FS-A1FM:

[Slot 3-1]
0000-3FFF: extended bios.
4000-5FFF: secondary mapper on pages 00-0F of Slot 3-3's
rom. Switch
address is 7FC4 (bits 0-3).
6000-7FFF: secondary mapper on pages 80-8F of Slot 3-3's
rom. Switch
address is 7FC4 (bits 4-7).
Initial value for 7FC4 is undefined. Because of this, all
pages 00-0F
have the same boot code.
7FC0-7FCF: I/O ports.
8000-FFFE: disconnected.

[Slot 3-3]
Basically an Ascii 8KB megarom. Differences are:
0000-1FFF: extra 8KB bank. Switch address is probably
6400, readable at
7FF0.
2000-3FFF: extra 8KB bank. Switch address is probably
6C00, readable at
7FF1.
Standard switch addresses 6000/6800/7000/7800 are readable
at
7FF2/7FF3/7FF4/7FF5.
7FF6,7FF7: always read 0.
7FF9: bit 2 (value = 4) activates ports 7FF0-7FF7.
In fact, extra banks are never used. Initial value for all
six banks is
A8 ( = page 2.


I think it is different from Panasonic 08KB Mapper for FS-A1WX/WSX/ST/GT.

Here is SLOT31-SLOT33 ROM

http://nlmsx.generation-msx.nl/forum/file.php?2,file=284


P.S. FSM.COM is made by Kichi (Japanese MSX User) to dump
from Modem Mapper Cartridge just like FS-CM1 / FS-A1FM.

http://www.msxarchive.nl/pub/msx/emulator/system_roms/Dumping_Tools/FSM.COM

This tool may be useful to realize Panasonic Modem Mapper emulation.