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D.S VARIOUS SIGNALS
The DCS contains the following different groups of
signals~
- I/O Interface signals (23 lines)
- V-RAM signals (34 lines)
- Character Generater (CG) signals (16 lines)
- Video signals (9 lines)
- Display mode selects signals (3 lines)
- Clock input (2 lines)
- Other signals (5 lines)
D.S.l I/O interface signals
DIOSLO : Display I/O Select (Input)
When this signal is "0", the CPU is enabled to access the I/O
port inside the gate array.
If this signal is "0", either IORDO or IOWRO becomes "1", and
the CPU is enabled to read or write the I/O port inside the
gate array.
IORDO : I/O Read (Input)
When this signal is low and DIOSLO is also low, the data of
the I/O port is transferred to the CPU through the bus
BOOO-BD07.
IOWRO : I/O Write (Input)
When this signal is low and OIOSLO is also low, the data from
the CPU is written to the selected I/O port inside the gate
array through the bus BOOO-B007.
DMESLO : Display Memory Selected (Input)
When this signal is low, the CPU or OMAC is enabled to access
the video RAM.
In the same condition, if either MERDO or
MEWRO is low, read and write operation is enabled.
MEROO : I/O Read (Input)
When this signal is low and OMESLO is low, reading operation
to V-RAM is executed, and the read data becomes effective in
the bus BDOO-B007.
MEWRO : Memory Write (Input)
When this signal is low and DMESLO is also low, the data on
the bus BDOO-B007 are written to the V-RAM.
o -
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