The First Computer Controls
The first computer to control a lumber sorter was designed around 1975 by Progress Electronics, Co. of Portland, Oregon. It used a National Semiconductor IMP-16 micro-processor. The program was usually written directly in machine code and burned into ROMs. This was before the IBM-PC was available to run cross-compilers. All the interface cards and I/O were custom built. The system was enclosed in a large box and all I/O was wired back to this central point.
This micro-computer control system was quickly replaced by a mini-computer design which used remote I/O. The computer used was the Computer Automation LSI-2. Most systems operated with 16K to 32K bytes of magnetic core memory. The program was custom assembly language, created with a paper tape operating system. A little later, 8" floppy disks (128K capacity) came along. I took over the programming around this time. The first program I wrote was custom assembly language. Later, I used a Computer Automation real-time system and FORTRAN compiler. These could be used to create fairly complex programs.
Here are some photos of these systems: