Articles tagged “PICAXE-28X1”
Emulators and neatened wiring
I've decided to switch to a regular 10MHz Z80 rather than a Z180, given the difficulty of using an SDIP 64. I now have a DIP 40 Z80 ready for use, but as I don't have the programmer for the Flash chip (which will hold the OS) there's not much I can do with it physically. I have therefore cobbled together a basic emulator to help develop some of the software beforehand. To cut hardware costs I'm going to try and handle input in software. One bit of hardware I'm planning on having is an eight-bit open collector I/O port.
Comments Electronics Emulation PICAXE PICAXE-28X1 Z80 Z80 computer
Experimenting with a 32KB RAM
The next component I thought I'd experiment with is the RAM. The project is an analogue recorder - a circuit that samples an analogue input periodically and saves it in RAM, and can be configured to play the recorded signal back afterwards. Yes, it says plating. A single RAM chip offers 32K with an eight-bit word size. This requires fifteen lines to address it, A0..A14. The PICAXE-28X1 that is to control the circuit does not have enough output pins to be able drive this address bus and a data bus (to transfer values to and from RAM) and a still have enough pins left over to control the various components.
Back to Hardware
I enjoy dabbling with low-level programming, but have never actually built a computer to run these programs. I think it's time to correct that, and as the BBC BASIC project has required me to develop an almost complete Z80 OS (the only thing that's left for the TI-OS to do is manage files) I thought a Z80 computer would be a good start. The planned specs are (as a starting point):
10 MHz Z80180 CPU;64KB RAM (2 32K×8 SRAM chips);128KB Flash ROM;Graphical LCD;Simple joypad input;Keyboard input (AT using either software AT routines or dedicated microcontroller).
Comments Electronics LCD PG12864LRS PICAXE PICAXE-28X1 Z80 computer