A Lisa Inside An FPGA

[sigma7]

I've connected an upper Twiggy drive to the LisaFPGA, but flipping the LisaFPGA power switch on with the drive connected does not power on the LisaFPGA.
...
P.P.S. Using the Apple 20W USB-C power brick to power the LisaFPGA. I figured that would be plenty of power.

I'd suppose the 20W rating of that specific brick isn't at 5V (USB-C devices negotiate the voltage from the power source, so one may be 20W at 20V, so only capable of 1A, thus 5W at 5V).

Try some other USB-C power sources.

[ried]

Try some other USB-C power sources.

Will do. Is there any harm in using my MacBook Pro USB-C power brick? It outputs various voltages, one of which reads 3.0A at 5.2V. I assume USB and the LisaFPGA are smart enough not to send too much power into the Twiggy drive in any case.

[sigma7]

does anyone know how to tell if it should be bootable?

The first block is what is loaded by the ROM. In a DC42 file, the first block starts at offset 0x54. Although this image has some data in the first block, it is mostly blank, and what is there does not seem to be executable 68K code.

A LOS1.0 DC42 disk image, for example, has 4EFA000A at offset 0x5C (4EFA is a jump instruction, so is a common thing to see at the beginning of executable code).

edit: corrected offset value

[sigma7]

Is there any harm in using my MacBook Pro USB-C power brick? It outputs various voltages, one of which reads 3.0A at 5.2V. I assume USB and the LisaFPGA are smart enough not to send too much power into the Twiggy drive in any case.

That should work.

The 5V from the brick is passed directly to the Twiggy drive (which is why the Twiggy may partially spring to life even before Lisa Power is pressed). 5.2V is safe as the spec is +/- 5%. The 12V is generated on board the LisaFPGA and is well regulated.

A USB-C brick is supposed to only output a higher voltage than 5V after negotiating with the device.

[ried]

Just tried using the MacBook Pro power brick. Same exact behavior as before. The LisaFPGA simply will not power up with the Twiggy drive connected. Hmmm...