Re: Device list: VIC-20

From: Ojala Pasi 'Albert' (
Date: 2000-12-09 16:27:57

> My book, "VIC  revealed" by Nick Hampshire, says colour RAM is at 9600 
> unless there is more than 3K of expansion memory. In that case you'll find 
> it at 9800 (page 112).
> My SCH says:
> 1001 00xx xxxx xxxx = 9000-93FF = I/O0
> 1001 01xx xxxx xxxx = 9400-97FF = COLOR
> 1001 10xx xxxx xxxx = 9800-9BFF = I/O2
> 1001 11xx xxxx xxxx = 9C00-9FFF = I/O3

The color memory starting address depends on the video matrix starting
address. If the video matrix is in the "upper 512 bytes of kB", the
color memory will be also. The whole range 9400-97ff contains 4-bit-wide
memory. Also, it is possible to have the video matrix 1024 bytes and use
the whole color memory.

Yes, the VIA address decoding is a bit weird. You can write to both
VIA's simultaneously by writing to $913x..

/His hands almost went to his ears in a strangely human gesture. Like a
 boy he looked, almost lost. God, that our immortal bodies could be such
 varied prisons for us, that our immortal faces should be such masks for
 our true souls./	-- Lestat in "The Vampire Lestat"
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