On 15 Jan 2012, at 17:10, Csaba Zvekan wrote: > Also I can't seem to find the control pins SHA, SHB, SHC and SHD ? where do they come from ? SHA, SHB, SHC are on the U806 (74LS273) top-left corner of page 52 of the pdf. SH7* is on U803 just below it. T.