In a typical Z80 RC2014/RCBus configuration, the Z80 processor, which is limited to a 16 bit address bus, can only directly access 64k.  The RC2014 Modules such as the 512K RAM/ROM modules use bank switching to allow the Z80 to access more memory. 

Although this works, it is a bit restrictive.  If you attempt to write a program that is larger than 64k, or needs to access more memory, its got to figure out how to access the various banks, and switch them in and out as required.  It can get complicated.

The eZ80 has a 24bit address bus, and when running in ADL mode, can directly address up to 16Mb of memory, enabling the ability to write larger programs much easier.

So for the eZ80 to shine, we need a new memory module that works with the 24bit address and not use any bank switching.

Therefore, I  developed a new Module for the eZ80 for RC CPU system.  The **2MB Flat SRAM module**.  It allows the eZ80 to see up to 2MB of linear RAM.  The module has sockets for up to 4 AS6C4008 (512k) SRAM chips.

I wrote a little CP/M utility (EZ80.COM) to help with managing and testing the memory and (I/O) systems.

The firmware has been updated to enable the extended linear memory:

              +-------------+
   0x00 0000  |             | On Chip 128k flash ROM
              |             | (boot up firmware)
              |             |
              +-------------+
   0x02 0000  |  ~ ..... ~  | Unused
              +-------------+
   0x02 E000  |             | On Chip 8K Fast RAM
              +-------------+
   0x03 0000  |             | External Banked Switch
              |             | 64K ROM/RAM
              +-------------+
   0x04 0000  |             |
              |  ~ ..... ~  | Unused
              |             |
              +-------------+
   0x20 0000  |             |
              |             | External 2MB Linear
              |             | SRAM
              |             |
              +-------------+
   0x40 0000  |             |
              |  ~ ..... ~  | Unused
              |             |
              +-------------+
   0xFF FFFF

Now all I need is a figure out a way to write applications that can run from within this linear address space and take full advantage of the eZ80!