Hi all,
Some of you might be familiar with my sample memory expansion mods for the Casio SK5, SK8, SK60 etc:
http://www.warningwillrobinson.com.au/index_files/SKexpansion.htmThese expansions typically used a Texas Instruments BQ1405y 4MBit NVRAM chip to give a 16x sample memory expansion (or BQ1406y for 32x) with sample memory retention when powered down with no batteries (have inbuilt battery with 10yr lifetime); they are a great chip.
Sadly, Texas instruments no longer make them:
http://www.ti.com/product/bq4015y.
Instead, they have provided details of an external memory retention controller chip that can be connected to any normal SRAM chip of the same size as the BQ1405y:
http://www.ti.com/product/bq2201/descriptionThe addition of this chip to a normal SRAM chip will effectively turn it into an NVRAM chip with the addition of a 3V coin cell battery, which will retain the samples in your SK sampler even if the keyboard batteries go flat or if you only use an AC adapter and no batteries. Here is the SRAM equivalent that you would use in the 16x expansion:
http://au.element14.com/alliance-memory/as6c4008-55pcn/ic-sram-4mb-5-5v-512kx8-32pdip/dp/1562900You don't actually need this chip as such to have non-volatile memory in the SK5/8/60 samplers - so long as you have batteries installed in the machine, it will remember the samples. But the controller chip + coin battery installation means you're not relying on the AA batteries to hold your samples - all 64 of them.
One big advantage of this change is that normal 4MBit SRAM chips are very cheap - a few dollars. Compare that to the equivalent NVRAM chip at $80 or so - if you can find them any more.
Cheers, Graham