Update README.md

README.md

@@ -41,3 +41,4 @@ I also updated a component placement drawing for revision 1,7 and uploaded it he
 
 Lastly for completeness, I also uploaded the ROM dump of the real ZX-81, which you are legally allowed to burn into a ROM and use with the ZX81+38. 
 
+On 5 juli 2022 I discovered that KiCad had changed back to the logic family of some libraries for wich I had changed the original logic family from LS logic to HC logic. I intended that all logic would be HC logic, just like in my ZX84+35 initial clone. But this may cause problems because HC logic and LS logic are incompatible. So the first thing I did was updating the BOM, to also see if there actually were HC replacements for the LS logic I had used by mistake, luckily all te HC logic I needed was available in DIP. Next up will be revision 1.8 of the schematic, which will also get a clock inverter using a spare half of a flipflop. This might be necessary to solve a timing error that can occur with EPROM's that are too slow to put pixel data into the shift register that results in all black character squares (due to the databus pullups that pull the databus high when nothing is driving it. Then I will correct the component placement diagram which also shows some wrong logic families. My last remark is that although theoretically the ZX81+38 should not work with mixed logic, it seems that in practice it still seems to work. I finished building up my own copy with mixed logic so I can check this for myself. Also note that I no longer recommend using sockets with machined pins, use dual wipe sockets instead. This is reflected in the BOM. Lastly perhaps thsi clone will not work with original N-MOS Z80 chips, its recommended to use modern (C-MOS) versions,