[sdiy] Partitioning feature of the DS1630AB..

[Jason Tribbeck]

Hi,

I'd not seen a partitioned ram system before I looked at the datasheet for
the DS1630AB.

It's method to add write protection for partitions of the memory, and in
order to activate it, you need to send a particular nibble sequence to the
top 4 bits of the address (A11 to A14), using read cycles. There are 16
partitions, each equal in size in memory (so each are 2Kx8).

The sequence needs to be F, E, 7, 7, 3, 9, C, E, 7, 3, 9, 4, 2, 4, A, 6, 9,
1, 0, 5 - and then send 4 nibbles that enable / disable writing to each of
the 16 partitions (1 = deny write; 0 = permit write).

It seems like you can get the partition and battery backup control in
(obsolete) DS1610 as well.

If you needed to implement it in something a bit more modern, then you'll
need to see if there is something that does something similar (I've not
found one yet), or implement it in something like a CPLD.

If you don't implement it, then all of your memory will be writeable, which
could cause problems for systems that are expecting the memory to be
read-only in certain areas.

Unfortunately, my quick scan of the datasheet does not indicate if the
memory defaults to being writeable or not. It could potentially retain the
settings from the last time the partitioning was configured (as it has
access to the battery backup).

On Sat, 1 May 2021 at 15:05, Jean-Pierre Desrochers <jpdesroc at oricom.ca>
wrote:

> What is the difference between the partitioning feature of a Dallas NVRAM
> DS1630AB
> and a standard 32k x 8 SRAM (regardless the non-volatile option) ?
>
> Both running at the same speed and 5v voltages ..
>
> Can the DS1630AB be replaced by a standard SRAM of the same size ?
>
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-- 
Confucius says: Man with problem who thinks solution is regular expression
now has two problems.

*/s/two/many/*
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