Taking a punt on a custom prototyping board design with an #rc2014 slant.
Only 38 pins wide as it's a push to fit 40 on the 100x100mm $5 form factor at the well known PCB house.
It's based on Troy Schrapel's HBC-56 design (https://github.com/visrealm/hbc-56/tree/master/schematics/proto). Took me *ages* to recreate it in KiCad from the picture of the original board.
The rails under the IC are the power lines, positive is the upper rail, ground the lower. Should allow easy connection to vcc/gnd for most dip packages.
Common ground all over the board, but each of the 6 sections has an isolated VCC. You can bridge them with solder, if needed. This was done to allow mixed 5v/3v3 on the same board (as we need to do more these days).
Each solder spot has an adjecent, connected spot to allow access to that pin, either via wire or header pin.
Finally, there's another two rows of columnar joined pins that go across each section, so it could be nice for buses.
I guess the proof will be in the assembly.
Oli W 🌱