Core memory and OS/8

Rick Murphy rick at
Tue Sep 22 19:42:38 CDT 2015

At 07:26 PM 9/22/2015, Charles wrote:
>One of the reasons I bought Vince's 32K SRAM board for my 8/A is 
>because I was having flakiness with my "real" core boards (two 16K and 
>one 8K).
>Now that OS/8 is running again, and my RL8A and two RL02's are as 
>debugged as they're going to get, I decided to experiment with the old 
>Put them back in the chassis and... the two 16K boards are now working 
>perfectly. I ran it for two long passes with DHKMAD (checkerboard 
>diagnostic) with no errors!
>What's strange, though, is that OS/8 won't boot unless both 16K boards 
>are in the backplane. Then it does boot and a MEM shows "32K MEMORY!" 
>as expected.
>Won't boot with 16K or 24K of boards, either.

That's strange.

>I thought that only 12K was mandatory (at least that's what the Device 
>Extensions manual says for an RL01). Or is that something that's set 
>up during BUILD?... I don't see anything in the OS/8 manual and I know 
>I had OS/8 running with 16K and 24K previously.

8K is enough to boot with a one-page system handler (and for a TD8E 
with the MR8E ROM). Otherwise, 12K is enough.
Maybe something is loading during boot that's breaking things - try 
"SET SYS NO INIT" before you yank the memory.

What happens when you try to boot with less memory?

BUILD does have the CORE command that limits how much memory OS/8 uses, 
but that limits the amount of memory used, not how much it requires. 
"CORE 0" says to use all available memory.

More information about the cctalk mailing list