I forget the model, but it was a Hewlett Packard Programmable Desktop Calculator (I forget the model), approximately as big as a typewriter (if there's anyone still alive that remembers what those were. Typewriters I mean. If you one of those that don't, google it).
ANYWAY... it had 8 "pages" of memory to hold instructions, with each page holding a maximum of only 64 "instructions" (operations or key presses). It had 10 "registers" that could each hold just one number (calculated value), ONE comparison instruction and ONE branch instruction.
The comparison instruction compared one register value to another, and then depending on whether the values were equal or not, would either skip the next instruction or not skip the next instruction. The only branch instruction that existed was to branch to the FIRST instruction of any of the 8 pages. So you would code the compare instruction and then follow it with a branch to another page for the not-equal case. For the equal case you would simply continue with your code in the current page.
It also had an optional attached card reader too, to read your manually punched punch cards ("punched" with a special pencil-like stylus they gave you) containing the instructions for your program so you could load them into memory via the card reader rather than have to manually type them in each time.
VERY primitive but LOADS of fun!