Re: Apple //c!

[spec@vax2.concordia.ca (Mitchell Spector)]

In article dalloff@freenet.columbus.oh.us (Dave Althoff) writes...

>I just obtained another addition to my collection (previously included a
>GS, an unenhanced ][e, an enhanced //e, and a Psion 3a)...an Apple //c.
>
>Okay, the first thing I did was to check that PEEK (whatever...it was in
>the FAQ) and find out that I have the "255" model....the old model.  Now
>what exactly is the problem with this model?

    There are no serious problems with the original ROM version, it just
supports less features than the newer revisions (see below).

>I don't have SmartPort?

    In a sense. You can connect a maximum of one external 5.25 drive to
the disk port (which can be booted by typing "PR#7") but that is all.

    The newer version of the ROM firmware (ROM '0') will allow you to
hook up one or more UniDisk 3.5 drives and daisy-chain external 5.25
drives to that. You can also connect up Smartport devices such as the
Chinook (now sold by Sequential Systems) external IIc hardrive.

>I can't run the serial port at 2400 baud?  What about 19,200 baud?

    You'll have to open the IIc and look at the part located at C-7
on the motherboard. A 74LS161 TTL chip is the "bad" part, while a
silver colored oscillator with a megahertz rating on it is the "good"
part. The problem is the TTL chip was used to divide the IIc's clock
to get timing of the serial ports, but turned out to be 3% too slow.
The oscillator is able to give a more precise timing.

    Apple IIc's manufactured between April 1984 and December 1984
had the problematic serial ports (there is a greater chance your
ROM '255' IIc is affected, but it is a _myth_ that all 255's have
the bad serial ports). Getting back to the issue, if you have the
faulty serial ports 1200 baud modems and higher may have a problem
functioning. It depends on the brand and model of modem you use, so
you may very well _not_ have any problems with some of the modern
modems out there (the best way to tell is to just try them).

>At the moment, I haven't quite decided what I want to do with this
>machine, but I am interested in a couple of options, for instance...
>
>o Hard drive...perhaps even adapated to fit internal, connected to the
>  floppy port.  Is the hardware out there?

    You need to upgrade the ROM to do that. Alltech sells it, but you
have to open one trace (with a sharp blade) and close another with a
drop of solder. This is because of the differences in size between
the old (16K) ROM and the newer (32K) ROM. Besides support for the
UniDisk 3.5 (and other "smart" devices) the new ROM added the mini-
assembler and diagnostic routines.

    As mentioned, Sequential Systems sells an external hardrive for the
IIc, but expect to pay a fair bit for one. I believe Applied Ingenuity
sold an internal IIc hardrive, which replaced the built-in 5.25 drive.
I would suspect they're rare to find though.

>o LCD display.  I know the one that Apple built pretty much stunk, but how
>  about anyone else's?

    Both the Apple Flat Panel Display and the C-Vue LCD display are
extremely rare. Occasionally you may see one being auctioned off on
comp.sys.apple2.marketplace, and they generally sell for US$150 and
up.

    I own a C-Vue LCD display which I'm currently using on my IIc+.
Despite its squished viewing area, 80 columns text surprisingly
looks very sharp and readable, better than on any of my Apple II
monochrome or RGB displays. Graphics and 40 columns text are very
viewable, but do suffer a bit from that squashed screen.

    The problem with the C-Vue is it is not back-lit. You need a
bright light source reflecting off the screen to be able to see
anything, and looking at it from _just_ the right angle. I find
that sunlight works best, artificial indoor lighting generally
isn't good enough. Another problem is white and black are swapped,
which is good for text but terrible for graphics. The Apple display
has an inverse switch, but apparently not as nice overall as the
C-Vue. Incidentally, I found an Apple IIc LCD display (screen only)
at a used computer shop, but didn't bother to pick it up since it
was missing the interface board, cable and plastic housing. I might
go back and pick it up, considering how rare they are. :)

>o Is there someplace I can look to find the port pinouts...particularly
>the serial ports (I can obtain the connectors more easily than the
>prebuilt cables), the power port, and the video expansion port (maybe I
>can build my own portable display...)

    The comp.sys.apple2 FAQ has them all listed I believe, though mail
me if you have trouble finding them (I can type them out if you need
them, I just have to dig up my Apple IIc Reference manual).

    The serial ports (similar to an SSC) are controlled by a pair of 
6551 UARTs but generally more limited than an SSC because there are
only five pinouts (one of which is a ground I remember).

Mitchell Spector
spec@vax2.concordia.ca