On 04-Nov-2011, Ian Abbott wrote:
On 2011/11/04 04:23 PM, Ian Abbott wrote:
Okay, the high-order byte is written first, but it doesn't say anything about the ordering of the remaining bytes of the four- or eight-byte values. (PDP-endian, anybody?) ;-)
Except that PDP-endian wouldn't have the high-order byte first, it would have one of the middle bytes (bits 23..16 for a four-byte value) first.
Yes, in PDP-11 storage, the lowest byte had the lowest memory address, but they were often written with the bytes swapped within each "word" (16 bits), so that a 32-bit value 0x76543210 would have bytes in the order 0x32 0x10 0x76 0x54. There were other permutations, too. Perhaps the documentation should say something like: For the 16-bit value 0x3210, the bytes are 0x32 followed by 0x10. For the 32-bit value 0x76543210, the bytes are in the order 0x76 0x54 0x32 0x10 (is that the case?) For the 64-bit value 0xFEDCBA9876543210, ... For character data, the bytes are written leftmost character first, and sequentially as one would read them left to right in English, and terminated with a null byte. Dave C.