Pi Pico now boots to MMBASIC


Mar 24, 2017

I'm trying to hack a VGA cable with some resistors, as the latest beta theoretically supports.
Thinking maybe I can stuff this all inside an old PS/2 keyboard. Without pins, its fairly small.

By default or button press, boots like a memory stick. Drag and drop firmware on it is easy.
Serial device driver (after basic is loaded) can be a bit of a pain. If you have Win10, it finds
a COM port without any trouble. But may take some .inf file editing to force a generic serial
for older Windows. Then talk to it by any VT100 terminal emulator (I use Teraterm) untill you
configure some other preferred console. Supports several flat panel types if VGA ain't your
thing. My objective to disconnect from Windows soon as possible.

Also simple (in basic) to configure a stable near 2x overclock no sink, gets you 252MHz.
A sieve of prime numbers didn't make enough heat to feel anything under my finger.
I find little agreement on what was the Pico's original default speed 125MHz, 133MHz?
Documentation for VGA firmware sais compatible only when clocked 126000 or 252000.

Sadly it doesn't seem able to accept a USB keyboard directly. Only PS/2, 3.3V RS-232,
or pretty much anything thru virtual com port via terminal emulator. PS/2 KB can be a
wire-only hack if yours happens to run with only 3.3V, otherwise wanting a pair of level
translators to mitigate 5V. Not inclined to mess with PS/2 till I get VGA working first...


I hacked a PS/2 over USB adapter (on the left) and mini SD adapter (on the right).
Many USB keyboards retain fallback to PS/2, for the adapters with nothing inside.
Always imagined smarts for that were in the PC BIOS, but its in the keyboard...

PS/2 over USB
pin1 = +5V
pin2 = Data
pin3 = Clock
pin4 = Ground

Still no VGA yet...
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