Altair 8800 Clone Firmware Version 1.6
Posted: March 12th, 2014, 10:14 pmFirmware version 1.6 for the Altair Clone is now available on the support page.
While working on a project unrelated to the Altair Clone, I discovered that the 2SIO board forces a single 500us wait cycle on the 8080 processor during input operations. I've read the 2SIO manual 100 times, but just now noticed this fact! Altair Clone firmware version 1.6 incorporates this wait state in the 2SIO emulation. The other hardware devices emulated in the Clone do not generate a wait state.
One effect of this wait state is a dim, but obvious glow in the WAIT LED on the front panel whenever the processor is polling the 2SIO status register while waiting for input. So we now have one more blinking light to watch on the front panel while the computer runs!
Mike
While working on a project unrelated to the Altair Clone, I discovered that the 2SIO board forces a single 500us wait cycle on the 8080 processor during input operations. I've read the 2SIO manual 100 times, but just now noticed this fact! Altair Clone firmware version 1.6 incorporates this wait state in the 2SIO emulation. The other hardware devices emulated in the Clone do not generate a wait state.
One effect of this wait state is a dim, but obvious glow in the WAIT LED on the front panel whenever the processor is polling the 2SIO status register while waiting for input. So we now have one more blinking light to watch on the front panel while the computer runs!
Mike