There was a cute little OLED product which used an 8MHz crystal. They also tried to run the Prop at 128MHz. Some code would work at this speed but some instructions caused the device to crash.
Most of us who used it ran it at 64MHz. I'm pretty sure I still have my uOLED 96 Prop somewhere in my collection. There wasn't much programming space left after all the OLED driving code was loaded. IMO, it was a pretty novelty.
I have 3 of those. Those were pretty good in the day, but they discontinued them.
BTW you're not going to run reliably at 128MHz no matter how good you are! There were lots of exhaustive tests done many years ago. With a proper design I run reliably at 104MHz and am totally confident that 108MHz works reliably too. But I wouldn't guarantee anything higher.
Yes, that it didn't work at 8MHz still remains. Quite true.
But, at 7.3728MHz (64x 115200 baud) XTAL1+PLL16X it does work for me.
This is 2x VGA cogs, 1x keyboard cog, 1x ACIA (z80 interface) cog, 1x serial cog, and 1x SPIN control cog.
With a tight 3v3 power supply and excess capacity. Short wires, small PCB and, of course, at room temperature. EDIT N = 4 test devices.
Pretty much aligns to the datasheet section 9.2 Fastest Operating Frequency as a Function of Temperature. Just on the (right) edge of working.
I wouldn't put it in any medical equipment, or on a rocket to the moon at this rate, but for the application it seems to be ok.
Comments
I have 3 of those. Those were pretty good in the day, but they discontinued them.
But, at 7.3728MHz (64x 115200 baud) XTAL1+PLL16X it does work for me.
This is 2x VGA cogs, 1x keyboard cog, 1x ACIA (z80 interface) cog, 1x serial cog, and 1x SPIN control cog.
With a tight 3v3 power supply and excess capacity. Short wires, small PCB and, of course, at room temperature.
EDIT N = 4 test devices.
Pretty much aligns to the datasheet section 9.2 Fastest Operating Frequency as a Function of Temperature. Just on the (right) edge of working.
I wouldn't put it in any medical equipment, or on a rocket to the moon at this rate, but for the application it seems to be ok.
Cheers, Phillip