The first "portable" GPS receiver I ever saw was during a tour of a relative's military base in the mid to late 1980s.
It was mounted in a travel case where the lid removed exposed the control panel. I want to say it was about the size of a shoe box. Similar in length and height to one of those hinged metal ammunition cans, but wider if I remember correctly. It seemed hefty enough to have a lead-acid battery inside, but they did not give details.
You set it on the ground and waited minutes for a fix. Then it just displayed numeric grid coordinates of your location with segmented digit display cells somewhat like a 1970s calculator.
It was mounted in a travel case where the lid removed exposed the control panel. I want to say it was about the size of a shoe box. Similar in length and height to one of those hinged metal ammunition cans, but wider if I remember correctly. It seemed hefty enough to have a lead-acid battery inside, but they did not give details.
You set it on the ground and waited minutes for a fix. Then it just displayed numeric grid coordinates of your location with segmented digit display cells somewhat like a 1970s calculator.