HP Forum Archive 19

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HP-71B FRAM Extension Message #1 Posted by Hans Brueggemann on 8 May 2010, 2:43 a.m. all, "inspired" by raymund's current thread on the HP-71B bus simulation, i thought it might be in order to leak some information on my two current HP71-B ram extension projects. (obviously, i am not the only one in this forum living curiosity with a logic analyzer..) 1) so far, i managed to successfully link a cypress 256 kByte SRAM to the bus, giving a total of 128 kByte usable RAM (because in the current development stage, only 1 nibble per byte is used). the whole thing easily fits into a front port module. 2) next step is to use a 512kByte FRAM instead of the SRAM and pack it into a card reader housing. the completed memory module will feature 16 user-configurable ID-registers, each defining a 32kByte block of the FRAM as either RAM or write-protected RAM(ROM). i am currently working on the logics for a nybble-to-byte merger (and byte-to-nibble splitter) in order to make the complete 256kB (512kB) available. the hardware is realized with an actel igloo FPGA and is still in a very early stage, but the design looks promising and might be useful to link any 8-bit parallel device to the 4-bit HP-bus. -->feature requests are welcome! best regards, hans

Re: HP-71B FRAM Extension Message #2 Posted by Paul Dale on 8 May 2010, 3:03 a.m., in response to message #1 by Hans Brueggemann Awesome! When can we buy them :-) Pauli

Re: HP-71B FRAM Extension Message #3 Posted by Klaus on 10 May 2010, 2:42 a.m., in response to message #2 by Paul Dale Very nice. I am definitely interested!

Re: HP-71B FRAM Extension Message #4 Posted by Alejandro Paz (Germany) on 8 May 2010, 5:46 a.m., in response to message #1 by Hans Brueggemann One of the important points to have in mind is power consumption. I haven't worked with the Igloo series but with the Spartan from Xilinx. They are many things... except low power. In my design I used a LM1117-3.3 without realizing the huge quiescent current it has... there are better alternatives :). I decided on a uC-powered design... let's see how it works.

Re: HP-71B FRAM Extension Message #5 Posted by Chris Foley on 8 May 2010, 5:48 a.m., in response to message #1 by Hans Brueggemann Very good news Hans. Looking forward to hearing more news from this work. Congrats!

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