Re: Apple IIc questions: Serial ports; Keyboard; drives; etc...

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

In article <2o2ro6$qcu@wea.eel.ufl.edu>,
Alexandra Griffin <acg@kzin.cen.ufl.edu> wrote:
> Hello,
> 	I just bought an old Apple IIc computer from a friend [snip]
> 
> Anyway, I've never owned an Apple II before and don't know much about
> them, but I'm trying to set up the computer as a serial terminal for
> my Linux machine.  It came with the ASCII-Express and ProTERM
> communication programs on floppy, both of which *mostly* work.  I am
> having a few problems, though:
> 
> 1.	I can't get this system to reliably communicate at 19200 bps.
> It works OK at first, but if a lot of text comes in at once characters
> get "dropped" occasionally, resulting in misaligned columns & other
> problems.

There are two possible reasons for this:

1. The IIc cannot keep up with 19200 bps.  This will depend mostly on
the software - I haven't used ASCII Express or ProTERM, so I can't say
whether this is likely.

2. The IIc has the original motherboard, which has a design flaw: the
serial ports are clocked at a speed which is slightly slower than
"standard".  This can result in lost or corrupted data, especially at
higher data rates.

To check which version of the IIc ROM you have, get into Applesoft
BASIC and type:

PRINT PEEK(64447)

The value will be one of:

255  Original IIc ROM
0    Updated ROM with UniDisk 3.5 support
3    Memory Expansion ROM
4    Bug fixes to previous version

If it says 255, you almost certainly have the original motherboard.
If it says 3 or 4, you almost certainly have the latest motherboard.
If it says 0, it could be the original motherboard or a replacement,
and it is hard to say which without opening the computer up and
looking for identifying features.  I haven't seen the revised
motherboard, only the original one.

The problem with higher speeds usually exhibits itself when using a
modem at 1200 bps or higher.  Some modems are less fussy than others,
and the problem seems to be more common as you go to higher speeds.

If you can prove that your IIc has this problem, you can get a free
motherboard replacement from an Apple dealer (which will also give you
a ROM upgrade to at least version 0).  There have been a couple of
messages posted about this in the last few days.

> 2.	Is there any way to distinguish between cursor-control keys
> and their ASCII equivalents (i.e. cursor-left and Ctrl-H; cursor-right
> and Ctrl-U; Return and Control-M)?

Not on a IIc (or IIe).  You can do this on a IIgs, because you can
identify that the Control key is down (but you can't distinguish
between Ctrl-leftarrow and Ctrl-H, for example, unless you bypass the
keyboard microprocessor's decoding, which isn't easy, and is only
possible on the IIgs anyway).

> The Apple comm. programs support re-mapping the cursor keys to
> VT100-compatible codes, but their matching control keys get changed
> as well.  This causes problems with programs like Emacs which use
> control keys a lot and expect distinct codes for all of them.

If you're using Emacs, turn off the arrow key mapping and use Ctrl-N,
Ctrl-P, Ctrl-F and Ctrl-B to move the cursor around.

> 3.	Are there still any Apple II software archives available on
> the Internet?  Could someone suggest a good site to check?

Yes - there are several Apple II FTP sites.  I'm sure someone can
provide you with a full list, but I don't have one handy.  One that
springs to mind is cco.caltech.edu.

> 4.	I've heard that Apple II 3.5" drives can read Macintosh 800K
> disks (which PC drives are incapable of doing because of the GCR/MFM
> mismatch).  Will Macintosh or II-GS external 3.5" drives work on this
> IIc?

Not as such.  The IIc only supports one type of 3.5" drive: the
UniDisk 3.5.  This looks very similar to the IIgs and Macintosh
external 3.5" drive (which is called an Apple 3.5 Drive), but is a
different colour (white instead of 'platinum').  If in doubt, look at
the label on the underside of the drive, which will tell you which
type it is.

To support the UniDisk 3.5, your IIc must have ROM version 0 or later
(i.e. the PEEK above must not report 255).  If it does say 255, you
can get a free ROM upgrade from some Apple dealers, or buy a new ROM
from Alltech Electronics (a minor modification to the motherboard is
required when installing the ROM - E-Mail me if you need details).

The UniDisk 3.5 has its own microprocessor.  The IIc isn't fast enough
to read directly from a 3.5" drive, so the UniDisk does the hard work
internally and transfers data to the IIc at a lower rate than with an
Apple 3.5 Drive.

The UniDisk 3.5 is able to read Macintosh 800k disks, provided you have
software on the IIc which lets you read HFS disks.  There is a freeware
program called HFSLink which may work on a IIc with a UniDisk 3.5 - I
haven't tried it.  HFSLink can read files from an HFS disk, but cannot
write files.

Another option is to use Apple File Exchange on the Macintosh to copy
files to/from a ProDOS-formatted 800k 3.5" disk, which the IIc can
read.  (Note: the UniDisk 3.5 is very slow at reading/writing disks
formatted at 2:1 interleave, which is the standard for the IIgs and
Mac.  The Apple 3.5 Drive is somewhat slow at reading/writing disks
formatting at 4:1, but less so.)

> The connectors look the same, but I've heard conflicting reports.  I
> don't want to borrow someone's drive and end up frying it! 

I doubt you'd fry it, but it definitely won't work.

> If these won't work, where's a good source for IIc drives?  The drive
> connector on the back has a 3.5" disk symbol on a sticker next to the
> engraved 5.25" symbol, so supposedly some kind of drive should work!

You can connect up to four external drives, if I remember right.  A
maximum of one 5.25" drive, or up to four UniDisk 3.5 drives, or some
combination of the two.  If you are connecting a UniDisk 3.5 and a
5.25" drive, you must connect the 3.5" drive first.

> 5.	Any chance of getting a cheap hard drive for this thing?  Even
> better, are there any controllers around that allow an old MFM or
> RLL-type hard disk to be used on this machine?

I doubt it.  The only type of hard drive which can be used on the IIc
is one with a SmartPort interface ("SmartPort" is the protocol used by
the UniDisk 3.5 drive).  There is only one that I am aware of: the
Chinook CT-20, which is currently sold and supported by Sequential
Systems (whose address and telephone number was posted in a recent
message on comp.sys.apple2).  They aren't all that cheap, unless you
can get a second-hand one.

As with a UniDisk 3.5, you need ROM 0 or later to support a hard drive.

> 6.	Does this computer support AppleTalk networking, and if so is
> it compatible with the regular Mac appletalk?  Typing "PR#7" at the
> BASIC prompt results in "Appletalk Offline." being printed on the
> bottom line of the screen.

Aha!  That probably means you have ROM 0 or later, since PR#7 boots
the external drive on the original ROM.

Apple were planning on implementing AppleTalk support for the IIc, but
never completed it.  It would have required a special box to be
plugged into the serial port, probably with its own microprocessor.

In short, you cannot network a IIc (unless someone comes up with a
SmartPort network interface).

> 7.	Failing that, what are the prospects for hooking up the DB-19
> drive connector on the back panel to another computer and using the
> host machine as a virtual disk server, or simulated hard drive?  I've
> heard talk of this being done for Commodore 64's... Are all of the
> signals on that port standard TTL, or is there analog stuff there
> also?  Please post or mail any technical specs. you have!

I suggest you get hold of the Apple IIc Technical Reference Manual if
you want to delve into this.  It is available from Resource Central for
US$30 (second edition).  That is one address I do have handy:

Resource Central
P.O. Box 11250
Overland Park, KS 66207

Phone 913-469-6502
Fax   913-469-6507


It would not be a simple task - you would probably have to implement
the SmartPort protocol in any device you wanted to connect to the port.

To do this requires more information than the IIc reference manual.
You would also need the SmartPort and UniDisk technical notes
(available free from ftp.apple.com, somewhere under the /dts/aii
directory) and possibly the IIgs hardware and firmware reference manuals.

I think the disk port signals are all TTL-level (plus power rails), but
there are only two inputs (sense and data).  The hardware side
shouldn't be too hard to implement, but a reasonable amount of
software support is needed if you want the device to be handled
automatically by the IIc.

E-Mail me if you want more details on this.

- David
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand