Re: Discovered the Hi-Res Basic!

From: David Holz <david.holz_at_grindwork.com>
Date: Tue, 31 Oct 2017 12:56:04 -0700
Message-ID: <353e32b0-fcb3-2853-0276-5e84ce7d2248@grindwork.com>
On 10/31/2017 12:43 PM, Ruud@Baltissen.org wrote:
> http://www.baltissen.org/temp/DB-hires.zip
> I already mentioned the triple question marks. But you will also see 
> some quite large areas W/O comment. Mostly these are areas with a 
> lot of juggling with unknown variables, so much that I took it for 
> granted (read: sorry, I'm lazy). So if somebody has a lot of spare 
> time, please be my guest and find out what is happening. 
>

Just a few ???-clarifications from a quick scan:

D_A2E9 are 16 screen codes representing 4-bit pixel coverage using block
characters.  Offset 1 = upper left, 2 = lower left, 4 = upper right, 8 =
lower right.

The cpx #$80 in GetCheckParams copies the high bit of .X into the carry
flag.  It's not missing a branch.  This use of CMP is common in things
like sign extension.


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Received on 2017-10-31 20:01:54

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