-- Version 1.11    -- dip4 delayed zero cross for LED anti flicker (not working)
-- Version 1.12    -- new SD card routine to support more cards
-- Version 1.13    -- clk tests reverted because of Ghosting
-- Version 1.14    -- display clock shift adapted to 400 for comboboard interrupts (not working)
-- Version 1.15    -- solved IRQ bug in pia6821, now display clock without shift and adpated speed
-- Version 1.16    -- CB2 (Soundselect) set to high during boot ( XandO problem with init SB)
-- Version 1.17    -- weak pull-up U10_PB,CV_CH,S33,U10_CA1,U11_CB1,Zero_cross because of 74LVC245A
-- Version 1.18    -- LED_0 activation after boot & SD read. Needed for clean init of Cheap Squeak board. (used in BallFA HW v1.11 )
-- Version 1.19    -- option dip4 activates delayed zero cross for LED anti flicker
-- Version 1.20	   -- (and v2.20 for Cyclone_IV) sdcard.vhd corrected, save calculation of sectornumbers