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AR# 3265

M1.4 LogiBLOX - Discrepancy between dual-port RAM simulation behavior and Dynatext documentation.

説明

Keywords: dual, port, dual-port, dual port, Dynatext, RAM

Urgency: Standard

General Description:
In the (Dynatext) LogiBLOX Reference/User Guide book, the function of the DPO pin on dual-port
RAMS is described as follows:

DPO
The Dual-Port Output is used to output the data that occurs on
the Dual-Port Read Address input of the DP_RAM module whenever
Write Enable Clock goes High.

Although this is not incorrect, it is misleading.

ソリューション

The statement in the book is true if you are writing to the
location that is currently being read (i.e., after a delay)
the value written into that location will appear on DPO.
However, you generally do not write to the
same location from which you read.

The value on DPO also changes depending upon the value of the
address bus DPRA. When this is stable, after a delay, the data
in that part of the RAM cell appears on DPO. This allows data
to be read from the RAM independently from the write strobe.
This feature is not made clear in the current documentation.
AR# 3265
作成日 08/31/2007
最終更新日 02/08/2001
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