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Caitlin

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I have started to modify the Z80 based system I mentioned in my last entry and it feels much more satisfying then coding at a PC for me.



That is the PCB layout of the system I am modifying. It was a general purpose controller with 2 serial I/O ports, 4 timer/counter interfaces, and between 56 and 64 bits of I/O depending on configuration. A lot needs to be done to allow memory bank switching, task control, "protected mode", plug and go, and several other things. If you use controllers in your hobby projects, feel free to give me some input on what additions you would find useful. One thing I have been thinking about is ADC/DAC interfaces.
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I think it's cool that you managed this using only two layers of silicon.

Was that a conscious decision or is that just how you do things?

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Very cool.

Quote:
...feel free to give me some input on what additions you would find useful.
I was going to say RS232, but it appears you already thought of that. *tries harder to be more original*

Most of the microcontrollers I've used only do exciting things in software (AT keyboard/mouse protocol, Sony IR protocol, rubbishy sound).

How are you intending to handle memory? ROM BIOS with Flashable EEPROM? Are you even intending to turn this into a full system (fixed input device, display, whatever) or just a general-purpose Z80-based device?

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I think it's cool that you managed this using only two layers of silicon.

Was that a conscious decision or is that just how you do things?


Thanks. It's a two layer printed circuit board, and I would use more layers but I didn't for several reasons, the most important of which are below.

1). The manufacturer I go through to get them made makes 2 or 4 layer boards, with the 4 layer versions having additional power and ground planes, so you still only have 2 planes to use for signaling. The power runs don't take up much space so it was cheaper to use a 2 layer board rather than a 4 layer one.

2). The original plan for this unit was to sell it to hobbyests, but the guy who I designed it with is going through some personal issues for the forseeable future and turned over everything to me. Anyway, back to the reason...Since it was for hobbyests I thought it would be good to make the board simple to rewire if a person should decide to do so. Having a 4 layer board could be a pain to rewire.


Quote:
Most of the microcontrollers I've used only do exciting things in software (AT keyboard/mouse protocol, Sony IR protocol, rubbishy sound).

How are you intending to handle memory? ROM BIOS with Flashable EEPROM? Are you even intending to turn this into a full system (fixed input device, display, whatever) or just a general-purpose Z80-based device?


You can get micros to do some neat things with the use of a little imagination and ingenuity.

Memory is EPROM with either banks of SRAM or FRAM depending on the end application/user options.

The plan is for a general purpose Z80 controller board where you will be able to plug expansion boards into slots. The system will recognize that a board has been hot-plugged, power it up, read the contents of its ID/BIOS memory, and handle the board accordingly. Voila, plug and use. The main board itself won't have many functions other than basic PIO/SIO, DMA, power management, CPU, etc. The expansion slots are where the specialized functionality is added.

I'm sure a lot of you are wondering why someone wouldn't just buy a regular computer instead of something like this. Again, a lot of hobbyests like the Z80 and can use it without designing/building/programming a system to use the Z80 family of components.

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