My favourite soviet computer is Setun, the only computer in the world using balanced ternary number system. Instead of bits which can be either 0 or 1, it uses trits, which could be 0, 1 or (-1). For simplicity, their values are often called "-", "0" and "+" (so one symbol for each value, without brackets etc)
This number system supports signed number from the beginning. For example, counting from -4 to +4 looks like:
"--" = (-3)+(-1) = -4
"-0" = (-3) + 0 = -3
"-+" = (-3) + 1 = -2
"0-" = 0 + (-1) = -1
"00" = 0 + 0 = 0
"0+" = 0 + 1 = 1
"+-" = 3 + (-1) = 2
"+0" = 3 + 0 = 3
"++" = 3 + 1 = 4
No need for one's complement which is used in binary computers to represent signed numbers. Extending balanced ternary numbers to bigger storage is easy: just put zeros at the front! (no need to duplicate most significant bit)
Rounding numbers is headache in binary numbers: add 1/2 lsb, handle "banker's rounding" (when exactly 0.5 should be rounded to nearest even number). But here just truncate all unwanted trits and we're done!
Usual computers have lot of flags in status register to indicate result of arithmetic operation. Zero flag, sign flag (if number is treated as signed), carry flag for unsigned and overflow flag for signed. But here ALL NUMBERS ARE SIGNED. And zero and sign flags are combined into one trit. It is "-" for negative numbers, "+" for positive numbers and "0" for zero!
For ferro-diode logic cells and memory (one example of this technology is core memory which was used everywhere including spaceships) this balanced ternary logic was very natural. Change direction of winding and by this you can change sign.
Too bad nobody found good implementation of balanced ternary for integral circuits, so it eventually became history.
About high prices: green capacitors shown on photos in this post contain great amount of precious metals, silver, platinum and often palladium. So buying these computers is like investing into precious metals!
My favourite soviet computer is Setun, the only computer in the world using balanced ternary number system. Instead of bits which can be either 0 or 1, it uses trits, which could be 0, 1 or (-1). For simplicity, their values are often called "-", "0" and "+" (so one symbol for each value, without brackets etc)
This number system supports signed number from the beginning. For example, counting from -4 to +4 looks like:
"--" = (-3)+(-1) = -4
"-0" = (-3) + 0 = -3
"-+" = (-3) + 1 = -2
"0-" = 0 + (-1) = -1
"00" = 0 + 0 = 0
"0+" = 0 + 1 = 1
"+-" = 3 + (-1) = 2
"+0" = 3 + 0 = 3
"++" = 3 + 1 = 4
No need for one's complement which is used in binary computers to represent signed numbers. Extending balanced ternary numbers to bigger storage is easy: just put zeros at the front! (no need to duplicate most significant bit)
Rounding numbers is headache in binary numbers: add 1/2 lsb, handle "banker's rounding" (when exactly 0.5 should be rounded to nearest even number). But here just truncate all unwanted trits and we're done!
Usual computers have lot of flags in status register to indicate result of arithmetic operation. Zero flag, sign flag (if number is treated as signed), carry flag for unsigned and overflow flag for signed. But here ALL NUMBERS ARE SIGNED. And zero and sign flags are combined into one trit. It is "-" for negative numbers, "+" for positive numbers and "0" for zero!
For ferro-diode logic cells and memory (one example of this technology is core memory which was used everywhere including spaceships) this balanced ternary logic was very natural. Change direction of winding and by this you can change sign.
Too bad nobody found good implementation of balanced ternary for integral circuits, so it eventually became history.
About high prices: green capacitors shown on photos in this post contain great amount of precious metals, silver, platinum and often palladium. So buying these computers is like investing into precious metals!
Ternary computing is fascinating! I fell down this rabbit hole recently. I should sit down and write up a piece on the basics.
I shared this because whoever even thinks about Soviet PCs.