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Memory addresses were never 8 bits. Some early hobbyist machines might have had only 256 bytes of RAM present, but the address space was always larger.
by rep_lodsb 4y ago
Memory addresses were never 8 bits. Some early hobbyist machines might have had only 256 bytes of RAM present, but the address space was always larger.
- compiler-guy 4y agoEven the Intel 4004--widely regarded as the first commercial microprocessor--had a 12-bit address space
- compiler-guy 4y agoThis got me thinking, and I went digging even further into historic mainframes. These rarely used eight-bit bytes, so calculating memory size on them is a little funny. But all had more than 256 bytes. Whirlwind I (1951): 2048 16-bit words, so 4k bytes. This was the first digital computer to use core memory (and the first to operate on more than one bit at a time). EDVAC (designed in 1944): 1024 44 bit-words, so about 5.6k. ENIAC (designed in 1943): No memory at all, at least not like we think of it. So there you go. All but the earliest digital computer used an address space greater than eight bits wide. I'm sure there are some micro controllers and similar that have only eight bit address spaces, but general purpose machines seem to have started at 12-bits and gone up from there.
- krallja 4y agoThe ENIAC was upgraded to be a stored-program computer after a while, and eventually had 100 words of core memory.
- antod 4y agoYeah, the 8bit machines I used had 16bit address space. For example from my vague/limited Z80 memories most of the 8bit registers were paired - so if you wanted a 16bit address, you used the pair. To lazy to look it up, but with the Z80 I seem to remember about 7 8bit registers and that allowed 3 pairs that could handle a 16bit value.