[Coco] Radio Shack's Audio Spectrum Analyzer for the CoCo 3

[L. Curtis Boyle]

Robert - from what I remember, to get the semigraphics modes to work on the Coco 3 (sans text characters of course), I just used the 3 LPR bits in $FF98 (least significant 3 bits).  00x does SG-24 (192 vertical resolution), and 010 does SG-12 (96 vertical resolution). I haven’t had a chance to test it over the last few days, but I did have some hand scrawled notes showing the pokes for a couple of different programs, and what mode they were using.
 
L. Curtis Boyle
curtisboyle at sasktel.net

TRS-80 Color Computer Games website
http://www.lcurtisboyle.com/nitros9/coco_game_list.html



> On Jan 16, 2019, at 8:37 PM, Robert Gault <robert.gault at att.net> wrote:
> 
> Curtis,
> 
> I've been playing with a disassembly of the disk version of the Analyzer program and have added a
> LDA #%1010
> STA $FF9C
> just before the program does a
> STA $FFC0  set up S-12
> STA $FFC2
> STA $FFC5
> Now with S-24 and the $FF9C poke on a Coco3 you get S-24 without any text letters but it does not help the Analyzer program to get S-12 or S-8 mode.
> Strangely enough the SN74LS783 specs indicate that while S-8 and S-24 can produce letters as well as block graphics, S-12 should just produce block graphics so maybe the disk version of Analyzer is incorrect.
> 
> Whatever, there are two places in the program where $FFC0-$FFC5 gets changed and I've tried lots of combinations with and without the $FF9C change. Nothing gives the desired result on a Coco3.
> In S-24 mode there is no text and the screen is half the required vertical size. In what I assume is S-4 mode with many changes to the program to reduce the screen size on the vertical axis, there is not enough vertical space for the needed details.
> 
> I'd be happy to send you my disassembly and my initial mods to play with if you want. Maybe you can get Steve's program to work on a Coco3.
> 
> Robert
> 
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