Irish chain, block construction

Block finishes 9 inches
Four-block units finishes 18 inches

Irish chain works easiest with even numbered rows and columns, so I plan to make it 10 by 10 (100 blocks) to be 90 inches square. 
There will be 50 Block A and 50 Block B.

Could also make it 8 by 8 (64 blocks) to land at 72 inches square, or 8 by 10 (80 blocks) to be 90 by 72 inches, 
ALSO, can be made with odd number blocks if you want an asymmetrical quilt. I like this arrangement when there is less going on than my multi-fabric quilts.

Directions here are for an X being prominent in the blocks. An O can be prominent by changing the orientation of the block units. See examples below.

Note: this isn't a true Irish chain as the chains butt up against each other. I'm ok with this!

For each block (100 total)
Solid: Ten squares cut 2 inches
Print: Ten squares cut 2 inches; Two rectangles cut 3 1/2 by 5 inches; Two rectangles cut 2 by 3 1/2 inches

Watch with directional prints to keep orientation horizontal for the rectangles. Or be happy with it going every-which way.

Piecing and pressing plan
There are two lay-outs, Block A (50 blocks) and Block B (50 blocks)

Pressing plans for Block A and Block B.  
Keep the center vertical seam unpressed until block unit lay-out.

Block A pressing plan
NOTE: block A has those horizontal 3 1/2 by 2 inch rectangles and 2 inch squares pressed with the seams away

Block B pressing plan
NOTE; block B has that same section with the seams pressed inwards.

Then sew A and B together, pressing that seam AND the two vertical seams in the blocks towards the B blocks.

Rotate one pair of blocks and sew along the horizontal seam. Don't press that yet.
Make 25  four-block units.

X orientation of the four-block unit--I used this in my quilt

O orientation of the four-block unit--I did not use that in my quilt.

Watch soon for layout for the top.
My design using a traditional block. Use at your pleasure.