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Piezo speaker is somewhat inaccurate as its actually a resonator. Being much louder at its resonant frequency. They are best when well supported by their edges with airspace under and

Oh, when using NV-ram in Z80 systems one needs to preserve the CPU state before power down.? And restore that state on power up. Easier way is an all CMOS Z80 system, then battery to run CPU and all

That's a 32K byte part. similar to 62256 as used on CPU card. The SIO board comes with 64K byte part. They can be used if pinout matches as "battery backed" Ram which is what they are. I have used

Hello, Anyone using NVRAM instead of RAM in Z80MC as described Z80MC Operating Manual page 4? -Does this NVRAM replaces the RAM on Z80MC or SIO card? -Can it be used besides Micro-Basic? -Default

After a few days, it seems like adding the 22k resistor between pins 1-2 of R4A did the trick. Haven't had any more issues with the #8 button. Some things to note: R4 is a 15k sip. That's what was in

I don't know,? I will need some time to set up and test here.

It can be activated through software, but I don't recall if the firmware made that available.?

Thanks Kerem, I’ll give that a try. Paul

It is louder if the Piezo speaker is not in contact with the chips below, and suspended in the air with the ground wires. [email protected]> wrote:

I have the same problem. ?If I put my ear to it I can hear a faint beep. ?Checked all the wiring and connections, everything looks right. Paul

Yes, it actually beeps on each key press. I just couldn't hear it. Is there anything else I can do with it? Mitch

Each key press creates a beep as well as turns on the led. If you don’t hear a beep, I would check to see if the opto coupler is installed correctly. [email protected]> wrote:

I finally added the piezo speaker to the Z80MC. It only took me 2 years! What I'd like to know is how is the speaker accessed? I half expected there to be a beep or something when the system booted up

I just did the same thing. Added a 22k resistor to R4 pins 1-2. Since my problem was intermittent, I'm hoping this resolves the issue. Mitch

Removed the SIO card, now I am getting in12 78 Is it possible that the SIO card interfering with input port 12? SIO card is a new one, assembled with great caution and seem to be working fine, except

When I use the instructions on page 24, Examine Input Port, Press 5 12, read in12 78, instead I am getting blinking FF. Is this normal? Does this indicate in have an HW problem?

The comment on TTL was a generalization. Also likely any Nmos chips and others will be dead. That will include most of the parts like the Ram chip, uSD is plugged in, and as mentioned already most

Thanks Allison. I have replaced the 74SL259 with a new one, but didn’t make any difference. [email protected]> wrote:

Any TTL (74LS259) will react very badly with overvoltage. Most of the CMOS may tolerate it. Allison

Now that the Front Panel is working, I need to fix the SIO card which I think accidentally destroyed during the troubleshooting of the Front Panel. SIO card received 9V instead of 5V now all LEDs are