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URAM: What is it?
06-26-2014, 08:58 PM
Post: #3
RE: URAM: What is it?
(06-26-2014 04:23 PM)Christoph Giesselink Wrote:  
(06-26-2014 01:01 PM)jebem Wrote:  This is seen in the HP Pioneers series for instance (HP-27S, HP-42S, ...).
Does anyone knows what HP did mean with this URAM expression?

The High End Pioneers like the HP-27S and HP-42S use the 1LR2 Lewis chip. Among the Saturn core, this chip contain also a display RAM. The display RAM is memory mapped I/O, but from design not all RAM cells have a connection to the display. So some of these RAM cells are used as normal RAM the others to control the pixel in the display. This RAM is called URAM.

In opposite the external 8KB RAM chip in these calculators is called DRAM.

Thanks for the enlightenment!

Jose Mesquita
RadioMuseum.org member

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Messages In This Thread
URAM: What is it? - jebem - 06-26-2014, 01:01 PM
RE: URAM: What is it? - jebem - 06-26-2014 08:58 PM



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