I’m currently working on a custom development board, based on a quarter of a century old microprocessor, the Sharp LH5801. This microprocessor is the heart of the Sharp PC-1500(A) Pocket Computer, also known as Tandy TRS-80 Model II.
I’ve got plenty of documentation on the processor and the Sharp PC-1500, but what I did not have was a spare processor to play with. Recently, I got hold of a dozen of them, so no excuse anymore for not playing with them. 🙂
I started the design process by measuring out the package size in mm and wondered about the strange results I got… Well the size of LH5801 package is – bang on – 0.7 inches. It also has an odd number of pins for such a package size: 76 pins. Both make it pretty impossible to use the standard footprints provided by various package libraries. At least a short round of googling for packages for Eagle CAD or KiCad was unsuccessful.
So I had to design my own footprint which was smoother than expected. I used a already present layout with the correct footprint pitch and adapted copied/adapted the pins.
The part was made with KiPart (based on a CVS table). The pin description and layout was taken from the Sharp PC-1500 Technical Reference Manual.
The resulting KiCad part and footprint is in my Sharp PC KiCad Library at GitHub.