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

[dempson@actrix.gen.nz (David Empson)]

Larry Stedman <stedman@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.  )

Yes, that will be a 'B'. The part number didn't change, just the
revision letter.

> The enhanced is from 1984.  

Obviously it was originally unenhanced. The enhanced IIe came out in
1985 (as did the kit).

> 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!

Confusing chip markings don't help matters, but there are only four
chips I can think of on the IIe motherboard that might be the CPU. It is
one of the largest ones (40 pin package) and the motherboard legend
should have something pretty obvious written next to it.

The four 40-pin chips are the CPU, the IOU, the MMU and the keyboard
controller. The latter is easy to spot - it is in the lower right corner
next to the keyboard connector.

The IOU and MMU and probably labelled as such on the motherboard, but if
not, they are custom chips made by Apple and should have Apple-style
part numbers on them. The remaining one is the CPU. I haven't seen a
North American IIe motherboard up close so I can't tell you exactly
where they put it.

The number "6502", "6503", "65C02" or something very close to it should
appear on the chip, probably preceded by some letters, and maybe
followed by a letter.

> Is there an easy way to tell if these unenhanced have the 65C02 and/or
> the newer character generator ROM?

I don't know the part numbers for the character generator ROM off hand.

> IIRC, one can run certain programs that use MouseText to check the
> character stuff.

Something like the Apple IIe version of AppleWriter will give the game
away (inverse letters appearing as MouseText), but if you don't have
it...

To test for MouseText, do the following:

Make sure the 80-column firmware is not running. (Press Esc Ctrl-Q if
necessary.)

FLASH
PRINT "ABCDEF"
NORMAL
POKE 49167,0

The flashing text will change to either of two things:

If they stop flashing but remain inverse then you have the original
(unenhanced) character generator.

If they change to MouseText characters then you have the enhanced
character generator.

To restore the original state: POKE 49166,0

You can also write a program to test for a 65C02, but it is a little
more involved and I don't have the details handy.

> The 1988 plantinum IIe with a numeric keypad must have been a lot 
> wider... but sounds cool.

No, it was the same size. They managed to squeeze the keypad in by
eliminating the wide borders on both sides of the keyboard, and possibly
reducing the gaps between the keys.

-- 
David Empson
dempson@actrix.gen.nz