Good memory board for Heath H-11?
Jerome H. Fine
jhfinedp3k at compsys.to
Tue Feb 9 21:47:42 CST 2016
>Rich Cini wrote:
>Thanks guys. This is really helpful. I was getting confused between the M8044 and M7944 boards. Max memory for the LSI-11 is 32kw, right?
Correct, the maximum memory on a board is 32kw.
For an LSI-11 (aka PDP-11/03) without any MMU hardware,
the actual maximum memory that can be accessed must also allow
for the IOPAGE registers. Usually, the IOPAGE address range
is 4 kw which leaves 28kw for everything else, including RT-11
(assuming that is what you are running). There is one option
available with some hardware to reduce the address range
set aside for the IOPAGE to just 2kw which then leaves
30kw for everything else. Unless you are running a specific
program which requires the extra 2kw, it is probably not
worth the extra effort.
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