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Old 18 July 2013, 20:26   #1
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 21,381
Cirrus Logic based Z2/Z3 RTG board similarities

While developing board emulation, I noticed most Cirrus Logic based boards have nearly identical Zorro logic. (Excluding Picasso IV which is special). I originally thought they are different and only planned to emulate PicassoII/II+.

Picasso II/II+, Piccolo, Piccolo SD and Spectrum 24/28 all have 2 virtual autoconfig boards, one for IO ports and another for VRAM.

Piccolo/Piccolo SD and Spectrum have passthrough/interrupt enable IO port in exact same address (base addr + 0x8000) and uses exact same bits. (This port is not inside Cirrus Logic chip). They also have swapped R and B color components in hardware. Main difference seems to be autoconfig product/manufacturer id!

Did board developers base their own design on some existing design/product or did they share or copy designs?

EDIT: Please fix typo in title..
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