2 Jun
2002
2 Jun
'02
2:45 a.m.
Tony Duell wrote:
Hmm, why would the 6509 have more address space than a 6510? Or is
that "extension registers" the same as the "port" zero-page address
that is used in the C=64 to change the memory ROM/RAM layout? I
suppose if you used those 8 bits (or was it just 6 bit?) ports and
hook 'em to address lines, you could get a 24 bit address bus, which
gets you to 16 MB, or, if it's just a 6-bit port, it gets you to
4 MB. Not bad. Almost like the 8088, however you can't have a
stack segment different from a data and text segment. That 256 byte
stack is one big limitation in the 6502 family.
cheers,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
There was this
computer Commodore was going to make and then pulled
out of the market. It was based on the 6509 CPU, I guess right before
I believe there were several... One of them was the P500, aka the PET-II.
It's got a 6509 CPU, VIC-II video chip (I think), and uses the parallel
IEEE-488 bus for peripherals. A sort of cross between a C64 and a PET.
They are not _that_ rare in the UK, at least not compared with some other
'never sold' machines.
The 6509 is a 6502 core with address extension registers (I think one
used for direct addresses, another for indirect addresses) allowing the
chip to access 1Mbyte of memory.