| 摘要 |
PURPOSE:To cope with a continuous read out request by improving a read out speed by using a multiple port RAM and allocating a port for a write-only port and another part for a read-only port. CONSTITUTION:A RAM21 is the RAM of three ports connecting one port to an input line 22 and another two ports to an output line 23 and a memory cell 24 is connected to a bit line 25 and a word line 26 corresponded to an input port and bit lines 27 and 29 an word lines 28 and 30 corresponded to an output port. When the read out request is generated, a data Dn on the bit line 27 corresponded to an An-th word line 28 which is selected by a selector 31 is sent out. The contents of an address register 37 and a +1 adder 39 become An+1 and An+2 and the word lines 28 and 30 become An+2-th and An+1-th and the selector 31 selects the bit line 29 that is corresponded to the word line 30 and a data Dn+1 is prepared.
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