2 Jun
2002
2 Jun
'02
10:06 a.m.
Cameron Kaiser wrote:
Actually it was 64 8k banks (512k total). Any 8 banks could be mapped
into the 64k address space.
I wouldn't call it virtual memory because that usually refers to RAM
with a backing store file (usually on a hard disk).
--
tim lindner tlindner(a)ix.netcom.com
"Life. Don't talk to me about life." - Marvin, the android
On the 6509, there are four extra address lines,
giving you up to 1MB.
These lines are set by location $0000 for execution (which 64K "bank" the
code is running from) and by location $0001 for indirection (i.e., on
indirect indexed LDAs and STAs *only* the four bits in $01 would be
asserted on the address lines to get at another bank). Not quite segment
and offset addressing. :-)
And the 8086 segment addressing is a improvement?
The only clean 8 bit extended addressing was with the 6809 and OS/9 level
Two. Here you had 16 pages ( 4kb-each ) of virtual memory ,if I remember
right, per processes with the upper 256 bytes common memory.