about the keyboard test

[joaorsouza]

hello,

It is normal the necessity of click on the "tick tock clock" icon to pass the keyboard input test on the test memory.tst script?

 when i include ticktock in the input test:

while out <> 75 {
    tick, tock,
    eval,
}

it automatically recognize the keyboard input

[cadet1620]

You should not need to click on the clock icon (or add tick,tock, to the script).

The Keyboard is a sequential chip so its output changes independent of the clock. The Keyboard's out should be connected to the Memory's out without any synchronous (clocked) parts between them.

--Mark

[joaorsouza]

thanks for the answer!

i was putting the value of the keyboard on a register without the need, but in fact the kbd built-in chip is embedded with that right?

[cadet1620]

The Keyboard chip, in the nand2tetris abstraction, does not have a register in it. It continuously outputs the current state of the keyboard.

In reality, the would be one or more registers involved because the data is coming from the keyboard in a format (USB on my desktop) that is not directly compatible with the computer's memory system.

--Mark