Hello All, Am I right in assuming that nhc98 uses only 29 (out of possible 32) bits for addressing. Because, the top bit is used for ZAP, and least two bits are used to differentiate between various data nodes and so on. If this is the case then, we can't allocate more than 2^29 bytes or 2^27 (i.e 128 Mega Words) words for the total heap size (i.e Sp + Hp). Even if we were to use this maximum limit, the addressing has to start from 0x0, because otherwise we'll need more than 29 bits. So the actual limit is much less than 128 M Words. Or am I missing something ? Regards, ------------------------------------ Arunkumar S Jadhav, Masters Student, KReSIT, IIT-Bombay, India Ph: +91-22-25764967 http://www.it.iitb.ac.in/~arunk ------------------------------------ I exist because I work.
Arunkumar S Jadhav
Am I right in assuming that nhc98 uses only 29 (out of possible 32) bits for addressing. Because, the top bit is used for ZAP, and least two bits are used to differentiate between various data nodes and so on.
Yes. (However, we are thinking about changing the representation of the ZAP information to free-up the top bit, and see below for the other two bits.)
If this is the case then, we can't allocate more than 2^29 bytes or 2^27 (i.e 128 Mega Words) words for the total heap size
No. A heap pointer is always aligned to a 4-byte boundary, which is why we can use the bottom two bits for other purposes. Thus, the maximum heap size is indeed 2^31 bytes = 2^29 words. Regards, Malcolm
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Arunkumar S Jadhav -
Malcolm Wallace