Integer Overflow
Integer overflow (and underflow – I’ll lump them together) is one of those pesky things that creeps up in the real world and makes low-level software a little less clean and elegant than what you might see in an algorithms textbook. - Testing for Integer Overflow in C and C++ / wikipedia
# see also
# The World Before 8-bit Bytes Won ⮺
| Machine | Word size | Notes |
|---|---|---|
| DEC PDP-8 | 12 bits | Hugely popular minicomputer |
| DEC PDP-7 | 18 bits | Where UNIX was born, in assembly |
| DEC PDP-11 | 16 bits | Byte-addressed; where C grew up |
| DEC PDP-10 / DECSYSTEM-20 | 36 bits | Characters were often packed 7 or 9 bits at a time |
| Honeywell 6000 series | 36 bits | 9-bit characters; an early C target |
| UNIVAC 1100 / Unisys 2200 | 36 bits | Ones’-complement arithmetic, 9-bit chars; still has a C compiler today |
| IBM 7090 / 7094 | 36 bits | 6-bit character codes |
| SDS 940, ICL 1900, Harris | 24 bits | ICL used 6-bit characters |
| Burroughs B5000 family | 48 bits | Tagged, stack-oriented architecture |
| CDC 6600 | 60 bits | 6-bit characters, no byte addressing at all |
| Cray-1 | 64 bits | Word-addressed; in C, short, int, and long could all be 64 bits |
| Data General Nova | 16 bits | Word-addressed; byte pointers had a different representation than word pointers |
| Intel 8086 | 16 bits | Segmented memory; near and far pointers |
Written on April 19, 2021, Last update on April 19, 2021
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