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Four Banked Memory |
|
Signal |
In/Out |
Width |
Description |
|
Addr |
In |
16 |
Provides the address to perform an operation on. |
|
DataIn |
In |
16 |
Data to be used on a write. |
|
wr |
In |
1 |
When wr="1", the data on DataIn will be written to Mem[Addr] four cycles after wr is asserted. |
|
data_in |
In |
1 |
When rd="1", the DataOut will show the value of Mem[Addr] two cycles after rd is asserted. |
|
clk |
In |
1 |
Clock signal; rising edge active. |
|
rst |
In |
1 |
Reset signal. When "rst"=1, the memory will load the data from the file "loadfile". |
|
createdump |
In |
1 |
Write contents of memory to file. Each bank will be written to a different file, named dumpfile_[0-3]. Active on rising edge. |
|
DataOut |
Out |
16 |
Two cycles after rd="1", the data at Mem[Addr] will be shown here. |
|
stall |
Out |
1 |
Is set to high when the operation requested at the input cannot be completed because the required bank is busy. |
|
Busy |
Out |
4 |
Shows the current status of each bank. High means the bank cannot be accessed. |
|
err |
Out |
1 |
The error signal is raised on an unaligned access. |
This is a byte-aligned, word-addressable 16-bit wide 64K-word memory.
Requests may be presented every cycle. They will be directed to one of the four banks depending on the least significant 2 bits of the address.
Two requests to the same bank which are closer than cycles N and N+4 will result in the second request not happening, and a "stall" output being generated.
Busy output reflects the current status of each individual bank.
Concurrent read and write not allowed.
On reset, memory loads from file "loadfile_0.img", "loadfile_1.img", "loadfile_2.img", and "loadfile_3.img". Each file supplies every fourth word. (The latest version of the assembler generates these four files.)
Format of each file: @0 <hex data 0> <hex data 1> ...etc
If input "create_dump" is true on rising clock, contents of memory will be dumped to file "dumpfile_0", "dumpfile_1", etc. Each file will be a dump from location 0 up through the highest location modified by a write in that bank.