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Which IIc model (essay/draft)
- Subject: Which IIc model (essay/draft)
- From: sebugg@presby.edu (Stephen Buggie)
- Date: Mon, 4 Jul 1994 05:54:07 GMT
- Newsgroups: comp.sys.apple2
- Organization: Presbyterian C.
This is a DRAFT of a paper I wrote at the request of Mike Young, president
of the Apple Public Doman Club (APDC)
5821 Kerth Road
St. Louis, MO 63128
Phone: (314) 487-4160
Many readers of comp.sys.assple2 know plenty on this subject.
Comments are solicited; The final draft will be prepared on July
15th.
Send comments/corrections to: sebugg@presby.edu
Thanks. Stephen
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<OOOOOOOOOOOOOO>>>>>>>>>>>>>>>>>>>>>>>>>>>
IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC
Rev. 7/3/94
HOW TO TELL WHICH APPLE IIC YOU HAVE
====================================
Stephen Buggie
Clinton SC 29325
sebugg@presby.edu
Four models of Apple IIc were made from mid-1984 through 1989. Some
models can be identified by the color of the external plastic casing
but mainly they are distinguished by special features.
ORIGINAL IIC: (1984-85) White casing; does NOT operate an external
Unidisk drive; has NO internal self-test. Most numerous
type made. Has 16K of internal ROM. ROM code: 255 This
model has a defective timing crystal, which limits modem
use to the slower baud speeds (300 baud, or, if lucky,
1200 baud). FREE MOTHERBOARD UPGRADE of the original IIc
has been available for many years at Apple dealers
(Linzmayer, 1989). The free motherboard upgrade is
definitely worthwhile! The keyboard was made by Atlanta
Photocircuits Co.; its keys are prone to "stickiness"
which slows typing speed. An improved keyboard was
introduced for the Unidisk 3.5 IIc.
UNIDISK 3.5 IIC: (March to Sept 1986) White casing; externally
identical to ORIGINAL IIc. Can operate 800K Unidisk 3.5
from drive port; can also operate faster modem speeds
(2400 baud; possibly faster). Has built-in SELF-TEST:
Hold down both Apple keys firmly, then turn on power
switch; checkerboard display pattern fluctuates for two
minutes, then displays SYSTEM OK in center of screen.
(Any defective ICs will be identified by a displayed code.)
Has 32K of ROM. ROM code: 0 If PR#7 <return> is typed
on this model, then the screen message, "APPLETALK OFFLINE"
will be generated in response.
MEMORY EXPANSION IIC: (1986-87) Platinum grey plastic casing; has all
features of the Unidisk IIc, plus special feature that
there is a motherboard RAM-connector socket so that a
one megabyte RAM memory board can easily be installed
(Pre-owned Electronics (MA) offers these Apple ram board
for $39. Two subversions of the Memory Expansion IIc were
made: ROM 03 and ROM 04. There are no important
differences in performance between ROM 03 and ROM 04; the
shift to ROM 04 was done to repair an arcane bug in the
ROM firmware of ROM 03. Most users will not notice the
difference between ROM 03 and ROM 04. NOTE: RAM memory
boards can be installed in the Original IIc or in the
Unidisk 3.5 IIc, but installation is complicated. Fitting
extra RAM in either of the two earlier IIc models requires
removal and reinstallation of two large 40-pin IC chips:
the 65C02 microprocessor and the MMU memory management
unit. The socket-connector inside the Memory Expansion
platinum IIc is much more convenient (Statt, 1987).
APPLE IIC+: (1987-89) This was the last version of the IIc family. It
is easily identified externally: platinum grey plastic
casing; power supply is fully internalized in the computer
(i.e., no "brick on a rope" power supply as in all earlier
models); internal 3.5" 800K disk drive (5.25" external
drive can be connected as an option); built-in 4 MHz
accelerator (all earlier IIc computers operate at the
standard Apple ][ speed of 1 MHz). Speaker volume control
moved to top panel, above the keyboard. Back panel serial
port connectors were changed from the 5-pin DIN sockets
used on previous IIc models to the mini-8 connector used
on the IIgs or the Imagerwriter II printer.
========================================================================
Most IIc models can be identified by external appearance: The external
plastic casings of the Original IIc or the Unidisk 3.5 IIc are white,
while the casings of the Memory Expansion IIc or the IIc+ are platinum
grey. The IIc+ is the ONLY IIc model with the 3.5" disk drive built
into the casing.
The only two models that are externally IDENTICAL in appearance are the
Original IIc and the Unidisk 3.5 IIc. The quickest way to identify
which model you have is to activate the "self-test": Hold down the two
Apple keys, then turn on the power. If you get wavy lines scrolling
downward, then you have the Original IIc (too bad!); but if the checker-
board pattern of the "self-test" appears, then you have the Unidisk IIc!
(The free motherboard upgrade for the original IIc will enable the
computer to do the self-test.)
IDENTIFYING THE IIC MODELS VIA ROM TESTS:
These are two simple keyboard tests by which the motherboard type is
identified conclusively by checking its "identification byte" at ROM
location 64447, known also as location $FBBF in hexidecimal notation.
You type in the following coded messages, then note the computer's
response. The response tells you the model of IIc you have. Either
test is sufficient; both tests will give identification results that
match. (ROM identifier tests are unnecessary with the IIc+ because the
IIc+ differs noticeably in external appearance from all IIc models.)
(1) First, get the "Basic Prompt" symbol, ], by holding down and
releasing these two keys: <CONTROL> <RESET>. At the Basic Prompt ],
type PRINT PEEK (64447) followed by <return>. How does the computer
respond? If it responds with "255", then you have the Original IIc; if
it responds with "0", then you have the Unidisk 3.5 model; if it
responds
with "3" or "4", then you have the memory expansion IIc.
(2) The second ROM identifier test is similar to the first. Again, get
the Basic prompt by holding down and then releasing the <CONTROL> and
<RESET> keys. Then type CALL -151 followed by <RETURN>. The computer
will respond with an asterisk *, indicating that you are in the "system
monitor." Then type FBBF followed by <RETURN>. If the computer
responds with FBBF- FF then you have the Original IIc; if it responds
with FBBF- 00 then you have the Unidisk 3.5 version, and if it responds
with FBBF-03 or FBBF-04, then you have the memory expansion version.
REFERENCES
APPLE IIC TECHNICAL REFERENCE MANUAL. Reading, MA: Addison-Wesley,
1986. The Apple IIc family xxiii; Identifying your Apple IIc
xxiii-xxv. [hardcover volume, not to be confused with Apple Corp.
IIc Technical Manual (1984), a two volume red paper cover spiral-
bound set]
Linzmayer, O. W. Get what you paid for. [article on free upgrades
available for Apple ][ products]. INCIDER, September 1989, 7, 64-65.
Linzmayer, O. W. The IIc family tree. [main reference for this paper;
it describes the differences among the various IIc models]. INCIDER,
January 1988, 6, 59-68.
Statt, P. Go beyond the IIc's limit. [RAM boards for the various IIc
models]. INCIDER, September 1987, 5, 51-53.
Stephen Buggie
sebugg@presby.edu
(revised July 3 1994)
IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC IIC
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** S. Buggie sebugg@presby.edu IIe/IIc Ph: (803) 833-8337, 833-1632 **
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