NVRAM board for Z80/Z180

Here is the complete description of a NVRAM expansion board designed for my generic Z80180 CPU board. It is a very simple board containing two 128KB CMOS RAM chips, a lithium battery socket, a power switch circuit, address decoder and the Euro 64 connector.

The NVRAM board has no jumpers to configure, address decoding is defined by the connections from 74xx138 circuit to the RAM CS inputs.

Hardwired NVRAM physical address space is 80000-BFFFF hex.

Click here to view the circuit schematic.

I have assembled and tested one NVRAM board and it is used as a solid state disk under my OS-X 2.0 RTOS. Driver software for simple block access and full file system support has been written. An assembled IDE interface board is shown below.

Download mem1_pcb.zip which contains the schematic and PCB layout files in Adobe Acrobat (.pdf) format.

Download mem1_driver.zip which contains source code for some drivers, filesystem servers and test programs. The programs runs on OS-X 2.0 in my Z180 computer. Start looking at the main units: files.tml and ramdev.tml, the other files contains API:s and support functions.

For more information, questions, feedback etc please contact me at: francis.gormarker@swipnet.se 

Last updated: January 4 2004