SRAM

Block: SRAM (sram)
Block Author: Pierre Yves Droz, Henry Chen
Document Author: Ben Blackman

Contents

Summary
Mask Parameters
Ports
Description
- Usage

Summary

The sram block represents a 36x512k SRAM chip on the IBOB. It stores 36-bit words and requires 19 bits to access its address space.

Mask Parameters

Parameter	Variable	Description
SRAM	sram	Selects which SRAM chip this block represents.
Data Type	arith_type	Type to which the data is cast on both the input and output.
Data binary point (bitwidth is 36)	bin_pt	Position of the binary point of the data.
Sample period	sample_period	Sets the period with reference to the clock frequency.
Simulate SRAM using ModelSim	use_sim	Turns ModelSim simulation on or off.

Ports

Port	Dir	Data Type	Description
we	IN	boolean	A signal that when high, causes the data on data_in to be written to address.
be	IN	unsigned_4_0	A signal that enables different 9-bit bytes of data_in to be written.
address	IN	unsigned_19_0	A signal that specifies the address where either data_in is to be stored or from where data_out is to be read.
data_in	IN	arith_type_36	A signal that contains the data to be stored.
data_out	OUT	arith_type_36	A signal that contains the data coming out of address.
data_valid	OUT	boolean	A signal that is high when data_out is valid.

Description

Usage

The SRAM block is 36x512k, signifying that its input and output are 36-bit words and it can store 512k words. Each clock cyle, if we is high, then each bit of be determines whether each 9-bit chunk will be written to address. be is 4 bits with the highest bit corresponding to the most significant chunk (so if be is 1100, only the top 18 bits will be written). If we is low, then the SRAM block ignores data_in and be and reads the word stored at address.