Is anyone interested with the Z80?

That is what I'm planning. This is just the beginning. I was just starting where I was. I first thing I want to get accomplished is to get memory working and a serial terminal working so I can play around with it. This project will probably never be complete, but just further along . There is a lot of things I want to do but have to take it in steps. This weekend I want to get status LEDs set up. Reading and writing from memory, write an archaic is and watch what it can do. Then upgrade and upgrade from there.

Was doing some thinking .I have transceivers between the CPU and the address and data buses. Is it necessary to have transceivers between the memory and the buses, since memory will almost always be involved in most of the bus usage, ie. Dma.? Dreams like there should not be too much draw on the bus keeping memory on it. The chips are only enabled when memory is being called for anyhow. They do you think?  

Adding transceivers and buffers is a usual task for Z80 older designs when we used to use TTL.

The decision to use them depends upon the Z80 variant used.

I think the original NMOS variant can only handle  IOL=+2mA and IOH--250uA (1 TTL or 4 LS loads) whereas the CMOS variant IOL=+2mA and IOH=-1.6mA so ensure your design does not exceed these fanout limits.

If you plan to use DRAM with DMA, you'll need to ensure that all bus masters continue to refresh the DRAM but I'm guessing you'll be using SRAM.

Adding transceivers and buffers is a usual task for Z80 older designs when we used to use TTL.

The decision to use them depends upon the Z80 variant used.

I think the original NMOS variant can only handle  IOL=+2mA and IOH--250uA (1 TTL or 4 LS loads) whereas the CMOS variant IOL=+2mA and IOH=-1.6mA so ensure your design does not exceed these fanout limits.

If you plan to use DRAM with DMA, you'll need to ensure that all bus masters continue to refresh the DRAM but I'm guessing you'll be using SRAM.

Hi Rob,

Two pin metal cans are just crystals.  They require an accompanying circuit to make the them oscillate. The circuit can be as simple as two or three inverter gates with a couple of feed back resistors and a small ceramic capacitor.

The voltage across an oscillating crystal is small and the accompanying circuit will output a suitable or near suitable signal.

Here is an example circuit similar to that I used 35+ years ago.  For a Z80, it is also necessary to add a 330 Ohm pull up resistor to the output to meet the required clock input specification.

You can of course use 7404 inverter gates in lieu of the 7400 NAND gates.

Some variance can be used with the resistors. I've used 1K.

C2 is just a ceramic (or monolythic) Coulomb bucket capacitor. (Others in correctly call it a bypass or decoupling cap but it's really there as a electron store because there's nothing being bypassed or decoupled).

C1 is a trimmer pot allow the output frequency to be adjusted

Four pin metal cans whether they be small or larger are often crystal oscillators.  It is the crystal along with the necessary oscillator circuit. Only three pins are used. Voltage, Ground and Oscillator output.

To use it with a Z80 ensure that the output specifications are correct.

What type of Z80 are you using?

I started to use them but as a beginner, and using a breadboard(s), I opted to remove them as to the space, wiring, and debugging, was difficult . I will probably as them once I get a system running.  I'm getting really close . I have the z80 reading instructions from room and writing to ram.  I debugged that and to my surprise I worked after a few datalines crossed and a few address lines. Now working on the serial interface .

I have a question,. Might sound stupid, but I am a beginner.  I have some full can crystal crystal oscillators . What is the difference between the full can 4 pin ones and the smaller 2 pins.  I've googled it and I must have the search terms wrong because I can't find an answer.  Do the full can ones have the capacitors built in?  The datasheet I have form them tells me nothing but the pinouts.   I've checked the output work my oscilloscope but I think the 7.3436? MHz is to fast for it and am not sure if I'm getting a sine wave or a distorted square wave.  I have some 1mhz coming in the next few days off the same style and I'll check them. Thanks.