] Hi! |
] A|A
] (n n)
] \_/
]
] Luiz Eduardo de Souza Marques asked:
]
] > (...) Somebody kown something about MSX Engine? (...)
]
] MSX-Engine is the "MSX-in-a-chip": Z80, VDP, PSG and
It is also how a dutch MSX group called themselves. They released among many
other things a game called DIX. The original message was referring to this
MSX engine ;-)
] probably PPI in the same capsule. One just have to put it in a
] board with a video signal generator (S-VHS, compose video, RF
] etc.), a power supply, memory, some plugs and auxiliar I.C.s
] and "voila", a perfectly working MSX. I think turbo R has an
] MSX-Engine inside. I never opened mine (not that I hadn't
] tried, but that I couldn't - I was afraid to break something),
It does. It actually has 2 engines inside. One created by Toshiba which most
probably is also used in the latest 2+ models. It contains the Z80, PSG, PPI,
I/O port decoding circuits to generate the select signals for the VDP, the
printerport, the diskcontroller and other I/O ports. Furthermore, it contains
a memory mapper and DRAM control circuits. This memory mapper and DRAM
control circuits are however not used in the MSX turbo R.
The other one is called the S1990 and it is designed specifically for the MSX
turbo R. It is actually not that much of a real engine but more of a complex
bus-controller. It switches between the Z80 and R800 and it makes sure that
the R800 will be delayed enough when doing I/O accesses, or memory accesses
to the build-in ROMS or the cartridge ports. The exact delay depends on the
access being done. For example a memory read to an external slot will be
delayed more then a memory read to an internal rom. Actually, when accessing
the external slots, the S1990 will make sure that the same timing is used for
the signals as when the Z80 would be accessing the external slot. This is
obviously necesary as cartridges may depend on the timing of the signals as
specified in the MSX technical documentation.
Furthermore, the S1990 contains the internal memory mapper of the MSX turbo R
and it makes sure that the Z80 can access the internal memory when the Z80 is
running. This is not that abvious as the internal memory itself is connected
to the R800, which has a build-in DRAM memory management circuit! This is
also the reason why the mapper and DRAM circuits of the toshiba engine are
not being used.
Kind regards,
Alex Wulms
--
Alex Wulms/XelaSoft - MSX of anders NIX - Linux 4 ever
See my homepage for info on the *** XSA *** format
http://www.inter.nl.net/users/A.P.Wulms
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