Appendix D of the TS-2068 user manual gives four pages of “System Variables”, which most users kinda ignore. These variables are used by the TS-2068 operating system to control things, and we users can use the vars to advantage. The most confusing thing about the tables is the “two byte numbers”, which leaves us out in the cold climate of mis-comprehension. So, let us learn how to store a number greater than 255. A “8 bit” computer places a limit upon “how large a number” it can manage “in just one byte (memory address)” in memory. You can “LET a=999999” and the six digit number will STORE in the variable area. But, internally in the computer, that takes several bytes of memory. The minimum amount of memory required to store a number larger than 255 is two bytes, and is stored by POKE(ing) a smaller number to two consecutive addresses. EXAMPLE: POKE 60000,1 and POKE 60001,1. Now let us see what that means, in so far as “what number LARGER than 255” has been stored. The computer formula for finding out would be, PRINT PEEK 60000 + 256 * PEEK 60001. Try it. After some practice POKING two consecutive MEMORY ADDRESSES, and then PEEKING them back with the formula, you will find that resultant of each increase in a number poked to the HIGH address will be 256 digits higher, and the resultant of each increase in a number poked to the LOW address will be ONE digit higher.
The actual reason that a 8 bit computer can only STORE a number SMALLER than 256 in ONE memory address is that there are only 16 “address lines” to the Central Processing Unit (CPU). What is the MAXIMUM factor of 16? You are correct if you said “256”. “But, you said that the computer is limited to the maximum number 255 in one memory address”?? That is correct, because 255 actually represents 256 digits, INCLUDING ZERO. Count on your pinkies. One finger is 1, but a closed fist is 0. In computing, zero has as much significance as 1000. Elementary, eh Watson? Now what is the HIGHEST number that can be stored in TWO memory addresses? Find out by POKING 255 to two addresses and using the formula. Never did get to them SYSTEM VARIABLES, did we! We will deal with them in the programming section.