[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Problems! Disk ][ drive just whirs and whirs; IIc monitor knob stuck; IIe enhanced not...

mdj wrote:

On Apr 29, 9:53 pm, Larry Stedman <sted...@binghamton.edu> wrote:


Motherboards on the 2 unenhanced are both 1982
with a number 820-0064-B   (Or is the last 8?  Maybe B given Matt's info
about revision A.  )  There is also a number underneath that in white:
607-0164-M on one and the other lacks the letter.



Note that there was the later edition of the IIe motherbard fitted to
the platinum IIe's. This one also ends in "A" even though it's really
revision "C" :-) Sorry I don't have the part numbers handy

They're easily distinguished though - they have a single "CF" ROM
instead of a pair, and use 2 64kx4 DRAM chips instead of 8 64kx1's


Right.  I find that the easiest difference to spot is the 2 DRAMs
vs. 8 DRAMs.  Even in a bad picture, it's usually clear which
main board it is.


I tried comparing them to see I could spot the board differences--they
look identical!  Then realized from David's comment that it's not that 4
new, *extra* chips were added-- just the electronic innards of the chips
that were changed.  I had thought I could spot a CPU chip that would be
marked 6502 or 65C02---would have been too easy!



The boards are silk-screened so it should be clear, but there's only 3
potential parts that can be the CPU (The other two being the MMU and
IOU HALS). From memory, the CPU socket on US rev A and B boards is in
the lower left quandrant near the Auxiliary slot.


Actually, it's the only 40-pin DIP in rwo "B", just in front of the
bus slots, and a little to the rear of the memory expansion connector.


Is there an easy way to tell if these unenhanced have the 65C02 and/or
the newer character generator ROM?    IIRC, one can run certain programs
that use MouseText to check the character stuff.



A quick way is to boot the latest system disk which has the latest
ProDOS version 2.0.3 on it. 2.0.3 requires a 65C02 and will issue a

*** RELOCATION/CONFIGURATION ERROR ***

If one is not present.


I love the way software designers will bend over backward to avoid
introducing a new error message.  ;-)

-michael

NadaNet file server for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."