[A83] Re: Interrupt Vector

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: Interrupt Vector
From: "Henk Poley" <hpoley@dds.nl>
Date: Wed, 18 Dec 2002 11:43:05 +0100
Reply-To: assembly-83@lists.ticalc.org

> Van: Jeff Theusch <telepath75@hotmail.com>
> 
> After reading a Z80 online manual, I have found that the address of the
> Mode 2 interrupt vector is determined by the following:
> 
> Bit 15 - 8: I Register
> Bit  7 - 1: Perhipheral (assumed to be random)
> Bit      0: ALWAYS 0
> 
> This means that the table only has to be 256 bytes, not 257, and that
> the interrupt vector can point to anywhere, not just to where the most
> and least significant bytes are the same.  This is contrary to many of
> the tutorials I have read about the TI-83.  Can anyone confirm or
> disprove this?

Ti uses a Z80 clone, it seems to do it differently. Ask Tijl, he tried to
make a grayscale routine using this randomness. He know more about the
probability that this 'impossible' thing happens. :-)

	Henk Poley <><