The progress has been a bit slow on the 380Z front at the moment.
As you may have read, It displays nonsense on the screen and doesn’t do much else. I wondered if this was just a fault with the display controller card or more. At startup the machine is supposed to display a boot prompt and wait for a key press. however, I don’t have a keyboard. The keyboard interface is a simple parallel port with 8 bits for the decoded key code and a strobe to say that the data is ready. To try and make some progress I made a simple one key keyboard built into a 15 way connector.
All it does is permanently tie the lines needed to send a ‘b’ and then it has a push button on the strobe line. I push the button and the 380Z thinks I’ve pressed a ‘b’.
This didn’t change anything and so I think the problem is more with the logic board.
It has been suggested that the ROMS (EPROMS) might have lost their memory. I think their original life expectancy was only about 10 years and we’re way past that now. I would like to read them and compare them with the image files that I have. The chips used are TMS-2716, 2kx x8-bit EPROM from Texas Instruments. Their power requirements are the same as the 2708s and different to non-TI 2716s. I have been able to borrow an EPROM programmer and I have the needed adapter on order from the USA but unfortunately the seller has had some problems with his supplier and it’s taking longer than I had hoped.
When it gets here I’ll be on the case.