16 Mar
2004
16 Mar
'04
4:28 p.m.
Jay West wrote:
Yes, but I must be missing something, it doesn't
make sense to me. Is the
manual you're looking at for the A, or S? S has room for more modules.
"2100 computer". But it describes four modules, 0 through 3. 10 bits of
ROM address with the high two being the module number.
That sounds like the range for all 4 possible modules
is 0-1777, which also
jives with the same manual saying that bits 8-0 (9 bits) are for the
"address". I'm definitely missing something in my understanding.
1777 is 10 bits. Bits 9-8 are the module number. Bits 7-0 are the address
within the module.
While I want to understand the whole scoop for my own
knowledge, what I
actually need at the moment is much simpler. Given a microcode call of
105xxx, how can I determine if this is calling code in module 0, 1, 2, or 3.
"These are translated by the mapper to specific control store
addresses, depending on which module has been chosen (and hard-wired)
to contain the primary entry points. The rule here is that the lowest
numbered module in the system, excluding module 0, must contain the
primary entry points. ... In all cases, the first 16 locations of
the appropriate module are dedicated to this purpose."
-Frank McConnell