Answer by Will Hartung for Why did CP/M require RAM in the bottom part of the...
In contrast to many other CPUs, a feature of the 8080 is the separate address space for I/O devices. Other CPUs (like the 6502) used memory mapped I/O. As a result of this architecture, the entirety of...
View ArticleAnswer by Jules for Why did CP/M require RAM in the bottom part of the...
Along with the specific reasons why CP/M needed to have the memory map it used, in general, for an Intel 8080 or Z80 based computer to be truly flexible, you must have RAM in the first 128 bytes. This...
View ArticleAnswer by tofro for Why did CP/M require RAM in the bottom part of the...
The 8080 that CP/M was originally designed for has very limited possibilities to produce code that can run anywhere in memory - Everything has to have fixed addresses. This results in the need that...
View ArticleWhy did CP/M require RAM in the bottom part of the address space?
A Z80 on RESET, starts executing from 0x0000. This is why the ZX machines and so many others have ROM at the bottom of the address space. Presumably an 8080 is the same. But as I recall, a CP/M binary...
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