Success.

Instructions to get the Hopper 6502 BIOS (and file storage) up and running on MECB 6502:
https://www.youtube.com/watch?v=nA1jQ1Mtr4c

Well, that explains a lot.

Thanks David. I'll take another swing at it now ..

It seems like the simplest thing but I've had no joy trying to read from PA0..PA7 (or PB0..PB7 but I figure that's because of the sound chip).

My initialization code now looks something like this (6502 assembly):



// Motorola 6821 PIA (Peripheral Interface Adapter)
const uint PORTA = 0xF010 ...

lenzjo wrote: Tue Jul 16, 2024 1:32 pm MECB SYS-IO card. It has a PS2 kybd port, RTC chip with battery backup, dual uart and a 6522 onboard.

Sounds like a good board. Schematic?

I just thought I'd check-in with the Forum, to see what I've missed, before I dive back into some more KiCAD fun. :geek:

I'm glad to see you're making great progress, and solving those ever-arising challenges!


Thanks Greg.

I just uploaded my tutorial videos documenting the process we went ...

Sadly, it appears I'm not quite done yet. I am getting 1000 ticks on each blink of my LED and output to serial (TICKS0..3 increments in multiples of 0x03E8 as expected).
However, the delay between each tick is much longer than 1 second. This applies for setting the timer 1 latch to 1000 for 1Mhz and ...

I set up timer 1 in continuous mode and made a real time clock..

I appreciate that. Thanks. I plan on doing a few tutorials on this in order to make it easier for the next person. This will be good for the one where I add the 3rd I/O component (the ACIA : real time clock output to the serial ...

The code sets up the 6840 to cause an interrupt after the countdown from some value (timer_LSB/timer_MSB); for each interrupt a 32-bit counter is incremented. The main loop simply reads the 32-bit counter and writes it to the terminal.

It's not exactly what you asked for but I hope that providing ...

My latest (non working) attempt for review. The ISR is never triggered.

(complete source here: https://github.com/sillycowvalley/Hopper/blob/main/Source/Runtime/6502/Devices/PIA6821.asm#L91 )

// Motorola 6840 PTM (Programmable Timer Module)
const uint TCR = 0xF000; // Write: Timer Control ...

lenzjo wrote: Sun Jul 14, 2024 8:21 pm I just found a rather tasty pdf you might like

I already have the datasheet, thanks. That's how I wrote my attempt at a driver that isn't working. I'm looking for sample 6502 source code now.