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# FPz8 - An open-source VHDL implementation of the Zilog Z8 encore

FPz8 mk1 v0.99

- Version: 0.99 Nov, 24th, 2016 (changed LDWX instruction, interrupts, condition code function, debugger command processor)
- Version: 0.91 Nov, 15th, 2016
- Version: 0.9  Nov, 11th, 2016

FPz8 is a softcore almost 100% object-code compatible with the Z8 encore microcontroller line. Current implementation includes 
2kb of file registers (RAM), 16kb of program memory (using FPGA RAM), 8 vectored interrupts with programmable priority, 
full-featured onchip debugger 100% compatible with Zilog's OCD and ZDS-II IDE.
It was designed to work as a SoC and everything (except the USB chip) fits inside a single FPGA (I have used an Altera 
Cyclone IV EP4CE6 device). The debugger connection makes use of a serial-to-USB chip (it is part of the low-cost FPGA 
board used on the project).
In a near future I plan to add some more features to the device (such as a timer and maybe other peripherals).
The idea behind the FPz8 was to learn more on VHDL and FPGAs (this is my second design using these technologies). I also 
believe FPz8 can be a very interesting tool for learning/teaching VHDL, computing and microprocessors/microcontrollers 
programming.

You are free to use and to modify FPz8 to fit your needs, except for comercial use (I don't expect anyone would do that anyway).
If you want to contribute to the project, contact me and share your thoughts.
Don't forget to credit the author!

Note: currently there are only a few SFRs physically implemented, they are:
0xFC0 - IRQ0
0xFC1 - IRQ0ENH
0xFC2 - IRQ0ENL
0xFCF - IRQCTL
0xFD2 - PAIN
0xFD3 - PAOUT
0xFF8 - FCTL
0xFFC - FLAGS
0xFFD - RP
0xFFE - SPH
0xFFF - SPL

What else is missing from the original architecture?
A: no watchdog (WDT instruction runs as a NOP), no LDE and LDEI instructions (data memory related), no option bytes,
   no data memory related debug commands, no CRC debug command, no ID bytes

FPz8 was tested on an EP4CE6 mini board (50MHz clock)
http://www.ebay.com/itm/EP4CE6-Mini-Board-USB-Blaster-Altera-Cyclone-IV-FPGA-CPLD-Nano-Size-

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