Quirks, odd things, etc.

[PashPaw]

When looking over the source I noticed this in the 1973 XDDT pt. 1 listing on page 14:

I know that Moby memory existed for the 36-bit DEC computers. However, as mentioned in the BBN Report No. 1673 on pg. 7 (real page 13):

I'm not entirely sure what is going on here. I know it has more than a single 4K bank, but how were they expanded? Were they standard Type 12 modules?

[larsbrinkhoff]

I think "moby" here is used in the sense "big". I.e. "search all users" is going through a lot of memory, as opposed to searching a single user. And "user" here may mean roughly the same as "process"; at least that's what I gather from early ITS code.

[PashPaw]

I think "moby" here is used in the sense "big". I.e. "search all users" is going through a lot of memory, as opposed to searching a single user. And "user" here may mean roughly the same as "process"; at least that's what I gather from early ITS code.

That's what I thought. And it would make sense if a user was a process.

[PashPaw]

I think I have an answer from looking into simh's documentation. Quoth the document on the PDP-1D:

Memory protection was implemented differently on serial #45 and serial #48. On
serial #45, the granularity of memory protection was 16KW; there were four
protection bits, covering the entire physical address space. On serial #48, the
granularity was 4KW; there were eight protection bits, covering a maximum of
32KW of memory.
Serial #45 had two additional features. The first was a trap buffer that recorded
useful information on a restrict-mode trap. The CPU could read the contents of
the trap buffer to help parse the cause of the trap; reading the buffer cleared it.
The second was memory renaming. Memory renaming did just that: it changed
the upper 2b of the program address to a different value. According to the
manual, memory renaming “cannot be bypassed”. Thus, it’s hard to see how it
was used, unless it allowed the non-executive memory banks to be effectively
swapped, thereby allowing user programs to run at a fixed base address.

In my time trying to figure out Macro, the cross-assembler is missing the PDP-1D instructions. I have been trying to implement them when I realized that so that Exec-III could maybe have a shot.

What is currently confusing me is the LCH and DCH instructions unless they're using the default FIODEC concise codes. I think I have implemented TAD correctly, though.