Good memory board for Heath H-11?

Richard Cini rich.cini at
Wed Feb 10 05:19:24 CST 2016

Jerome -- good point about the IOPAGE. Maybe I'll get an 8kw and 16kw board -- that gives me 28kw with the included 4kw.  I have no specific software so I don't need to tinker with reducing IOPAGE. 


Sent from my iPhone

> On Feb 9, 2016, at 10:47 PM, Jerome H. Fine <jhfinedp3k at> wrote:
> >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.
> Jerome Fine

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