Date   : Tue, 30 Sep 2003 10:52:40 +0100 (BST)
From   : BBC Micro <b_b_c_m_i_c_r_o@...>
Subject: Keyboard scanning/interrupts

Hi, I've got a question about the keyboard interrupts,
can anyone explain it concisely? ( I know about the
scan mode etc my questions are more to do with what
the code does...) I've got the "Guide to the BBC Roms"
but still a bit confused.

Can someone explain why the 10ms counter does the
keyboard check.  I was looking through the code but
seem to find dead ends as theres so many paths.

It checks to see if either of the two keypress
registers hold a key and the keyboard flag is true
then it does some checks of the keyboard scan.

Is this all to do with rollover checking?

Isn't this taken care of in the interrupt 0? How do
the two of them work together?

Regards



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