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Apple II Csa2 FAQs: Hardware Hacking, Part 13/25

( Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Part9 - Part10 - Part11 - Part12 - Part13 - Part14 - Part15 - Part16 - Part17 - Part18 - Part19 - Part20 - Part21 - Part22 - Part23 - Part24 - Part25 )
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Archive-name: apple2/faq/part13
Posting-Frequency: monthly
Last-modified: 2009/12/01

See reader questions & answers on this topic! - Help others by sharing your knowledge
The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
the II Computing Apple II site, 1997-2010.

Csa2 FAQs file ref: Csa2HDWHACK.txt  rev141 December 2009

Hardware Hacking

 001- What's a good hardware project book for the Apple IIe?
 002- How can I use a thermistor to read temperature on my A2?
 003- Will a prototyping Slot Board fit all Apple II's with Slots?
 004- What is the pinout for the Apple II series Slots?
 005- I've been getting Fatal System Error 0911. Is there a fix?
 006- Why does my GS Control Panel keep resetting to the defaults?
 007- How do I replace my GS "BatRAM" battery?
 008- Is there a program to record/restore Control Panel settings?
 009- How I can safely clean out dust from my Apple II?
 010- How can I safely remove oxidation from IC pins?
 011- After smoke came from my GS the KB doesn't work. What's wrong?
 012- What is the mini circuit board near the front of my GS for?
 013- How do I add RAM & set jumpers on the IIgs 1MB Memory Card?
 014- How can I move my IIgs to a PC tower case?
 015- How can I convert a IIgs into a portable IIgs?
 016- Where can I get Robot kits to use with my Apple II?
 017- Where can I get "Zip" package chips for my AE GS RAM-III card?
 018- What chip can I use to replace a bad RAM IC in my IIe?
 019- Could someone please post a resistor color code chart?
 020- What advantages does the ROM 3 GS offer vs. the ROM-01 GS?
 021- How can my ROM 3 GS + 8MB Sirius card do large file copying?
 022- My ROM 3 with RamFAST crashes with an 8MB Sirius. What's wrong?
 023- Where can I find Apple II diagrams?
 024- What No Slot Clock chip should go in my IIc+ and where?
 025- Where can I find Apple II socket, etc. pinouts?
 026- What IC do I need to use the GS-RAM Plus in my Apple IIgs?
 027- Where can I get prototyping boards that fit Apple II Slots?
 028- What are the numbers and functions of major Apple II ROMs?
 029- What is the C-One?
 030- How can I whiten my browned Apple II case, KB, mouse, etc.?

From: Paul Guertin

001- Could anyone suggest a good project book for the Apple IIe.
     I'm interested in using an old box for tracking the
     temperature in a water bath.

Vernier software publishes a book called "How to Build a Better Mousetrap" which contains 14 hardware projects for the Apple II. Project #6 is a temperature probe connected to PDL0.

ISBN for the book is 0-918731-16-X.
Vernier Software ( )
2920 S.W. 89th Street
Portland, Oregon  97225 USA
(503) 297-5317


From: Sheldon Simms

A good book is _Inside The Apple IIe_ by Gary B. Little. It isn't a project book, but it does have a good chapter on using the Game I/O connector for "electronics experiments."


From: Cyrus Roton

002- How can I use a thermistor (a resistor which has a variable
     resistance related to ambient temperature)  to read temperature
     on my Apple II?

You can connect a thermistor to a paddle input and supply a voltage to the other end. Current flows through the thermistor to charge a .022 mfd capacitor inside the apple2. When the paddle is read, the apple2 discharges the capacitor and resets a timmer. Then the cap is allowed to charge. When the charge reaches the trigger level (3.2 volts) the timmer is stopped and the count is read out.

The lower the value of the thermistor, the faster the charge and the lower the count. Also, the higher the voltage, the faster the charge.  A resistance of about 120K with a 5 Volt supply will give a count of about 250. You can add an external capacitor across the paddle input (to ground) to increase the charging time (if needed)

The formula is   charge=input volts * (1 - exp(-t/RC))

So, you can use a supply voltage and external capitor as required to fit the resistance value of the thermister (or other resistive component). Probably, the best way to find the correct values woud be to try a variety of values and plot the "count" as a function of the variable resistance. Then compare the plot against the resistance curves for the thermistor (probably not linear), and work out some conversion formula to use in your program to correlate "count" to temperature.


From: David Empson

003- Can I use the same prototyping Slot Board for all of the
     different Apple II's with Slots?

Prototyping boards certainly would be the same for the II, II+, IIe, and IIgs. The slots on all slotted Apple IIs are physically identical

There are minor differences between the slot signals on the various machines and on some slots in the same machine, mostly affecting rarely used special pins. (See Question 004 for more details on signal differences.)


004- What is the pinout for the Apple II series Slots; and, what
     differences are there in Slot signals from machine to machine?

Here is a quick summary of the Apple II series Slot signals:

Pin 1: I/O Select ($Cn00-$CnFF, where n is the slot number).

Pins 2-17: Address bus A0-A15.

Pin 18: Read/Write.

Pin 19: unused on the II and II+.  On the IIe and IIgs, this has composite horizontal and vertical sync on slot 7, and is unused on other slots, except for slot 1 on the IIe only, which has a diagnostic function to disable the oscillator on the motherboard.

Pin 20: I/O Strobe ($C800-$CFFF).

Pin 21: this is the RDY input to the micro on all machines, but it behaves a little differently in the IIgs, or in a machine with a 65802 installed.

Pin 22: this is the DMA pin on all machines.  Again, there are special issues for doing DMA on the IIgs which can cause compatibility problems.

Pin 23: this is used for the interrupt daisy chain (out) on all Slots except 7. In the IIe only, this pin can be connected to the GR signal (graphics mode enabled) via a motherboard modification.

Pin 24: DMA daisy chain out.

Pin 25: +5V.

Pin 26: Ground.

Pin 27: DMA daisy chain in.

Pin 28: Interrupt daisy chain in.

Pin 29: Non Maskable Interrupt.

Pin 30: Interrupt Request.

Pin 31: Reset.

Pin 32: this is the INHIBIT pin on all machines.  This behaves differently on all three machines: the II and II+ only allow the $D000-$FFFF ROM area to be inhibited.  The IIe allows RAM to be inhibited as well, but has strange interaction with main and auxiliary memory.  The IIgs only allows this signal to be used if the machine is running in slow mode.

Pin 33: -12V.

Pin 34: -5V.

Pin 35: unused on the II and II+.  On the IIe and IIgs, this is the colour reference signal on slot 7 only.  It is unused for other slots in the IIe, except for slot 1 where it provides a poorly documented facility to disable the keyboard address decoding.  On the original IIgs, slot 3 provides the M2B0 signal (Mega II Bank 0) via this pin and it is unused on other slots.  The ROM 3 provides M2B0 for slots 1 to 6.

Pin 36: 7 MHz system clock.

Pin 37: Q3 - Asymmetrical 2 MHz clock.

Pin 38: Phase 1 clock (1.023 MHz).

Pin 39: something called "USER 1" on the II and II+, which can be used to disable all I/O decoding if a modification is made on the motherboard.  On the IIe, this pin provides the SYNC signal from the micro, which indicates an opcode fetch.  On the IIgs, this pin provides the M2SEL signal, which indicates that a valid slow memory access is in progress.  This pin must be used by IIgs cards that decode the address without use of the IOSEL, IOSTRB or DEVSEL pins.

Pin 40: Phase 0 clock (1.023 MHz).

Pin 41: Device Select ($C0n0-$C0nF, where n is the slot number plus 8).

Pins 42-49: Data bus D7-D0.

Pin 50: +12V.


From: Rubywand, David Kopper, Guenther Unger, Gabriel Hawkins, Michael Mahon

005- I've been getting Fatal System Error 0911 and when I do the
     internal diagnostic it gives a system bad : 09010001.
     Is there a fix?

     Fatal System Error 0911 and Self-Diagnostic Test 09010001 mean the same thing: You are, very likely, experiencing one of the following malfunctions:

o- Temperature-sensitive ADB IC

     This problem was first identified in a 1988 article in issue #58 of Computist. If your IIgs is a true ROM-01 (produced starting in mid-late 1987) or a ROM 3, you are very unlikely to have an ADB IC with this defect.

     Otherwise ... A guess would be that you are running a ROM-00 machine which has been upgraded to ROM-01. If this is the first time you've noticed the '0911 problem, it is likely that this is the first summer you've owned and used this particular machine.

     Many early GS's come with an ADB IC which malfunctions over a narrow range of relatively low temperatures. Rooms are normally cooler during summer; so, this is when the error pops up most frequently. Some users first notice a plague of '0911 crashes after adding a System Saver-GS (which increases cooling).

Note: Some reports have attributed '0911 crashes to overheating of one of the two main ADB IC's. So far, it looks like these reports are cases of misinterpreting the actual failure syndrome-- i.e. warming up a cool IC enough to get into its failure region.

    '0911 bombs can occur 'any time' but they usually happen at startup and when doing OpenApple-CTRL-ESC accesses to the Desk Accessories (CDA's, Control Panel, ...) menu. As the machine warms up, '0911 crashes tend to become less likely.

     The bad news is that there is no 100% fix except to replace the temp sensitive ADB IC-- hard to do since it is soldered to the motherboard and, in any case, known-good replacements are difficult to find.

     As to _which_ ADB IC-- there are two, the ADB Controller and the ADB GLU- - our notes say the ADB Controller; but, we could have easily misidentified the function back then and the ADB GLU IC 'clicks' better with memories of the fix. (The ADB GLU IC is a square IC near the right front of the motherboard.)

Note: The easiest way to identify the temp sensitive IC is to apply the fix (below) and see if it works. If it does, fine. If not, it is easy to move the fix to the other IC. For now, my suggestion is to try the ADB GLU IC first.

     Since the problem is coolness, a decent cure is to tape a small 12V bulb (e.g. a 20-30 ma. panel light bulb) to the top of the ADB IC. Use duct tape and try to enclose the bulb and IC in a kind of mini-oven. Run the leads from the bulb to the +12V Fan power pins near the back left area of the motherboard.

     The idea is to quickly warm up the IC. I used a scheme like this on our early GS and 0911 bombs dropped from 4-5 per day to 2-3 per week. If you can safely power the bulb via an external power module (e.g. a calculator or radio 'AC adapter') so that the bulb can be ON at least a few minutes before powering up the computer, 0911 bombs might disappear entirely.

o- Defective keyboard, loose connector on KB, and/or a bad KB cable

     Some users report that swapping in another keyboard cured their '0911 crashes. In the same vein, a loose connector socket in the KB or a bad KB cable would be worth checking for.

o- System noise and/or lowered motherboard voltages

     If '0911 crashes suddenly appear after an accelerator or other power-sucking board is added, it is fairly likely that the added load has increased system noise and, possibly, also lowered motherboard voltages. 

     One possibility is that your power supply needs to have heavier leads swapped in. Also, you may need to jumper some of the power traces feeding Slots on the motherboard. For more discussion about this see Q&A 005-007 in Csa2POWER.txt.

     A defective power supply on the way to failing is another possibility. A failing power supply is more likely to be the culprit if '0911 crashes appeared 'from nowhere'-- i.e. nothing was changed, no new board was added, etc..

o- Poorly socketed Expansion Memory card

     With power turned OFF, try removing and replacing your Expansion Memory card.


From: Rubywand

006- My GS control panel keeps resetting to the defaults and
     forgetting the date between power-ups. What's wrong?

     Most likely, your battery-- also called the "BatRAM  battery" needs to be replaced.  When the GS is OFF, the battery supplies power to the clock and its attached 256-byte RAM. This small RAM is where Control Panel settings are 'remembered'.

     If, upon power-up, the GS believes the Control Panel settings have been messed up due to a low battery, it will reset the settings to their default (check-marked) positions.


From: Rubywand, Duncan Entwisle, Jerry Cline, Bruce Baker

007- How do I replace my GS "BatRAM battery"?

     The standard GS battery is a 3.6V Lithium type rated at 1.2AH. It is called the "BatRAM" battery because it keeps the Battery RAM and Clock IC going when you turn OFF power. To get to the battery, you must disconnect the AC cord and pop out the Power Supply.

     If you have a ROM 03 GS, you can slip out the old battery and slip in 'one like it'. On the ROM 01 GS, you will need a Lithium battery with leads you can connect to cut-off leads from the old battery-- about 3/4" each for most connection methods-- remaining on the motherboard. Be sure to mark the "+" lead on the motherboard with white-out.

     Night Owl Productions used to sell a convenient "Slide-On" Lithium battery made by Tadiran. It came with springy ends that would slip over the cut-off leads from the original GS battery.

     Radio Shack sells a few models of 3.6V Tadiran Lithium batteries. Mostly, these have smooth ends and are intended to fit into a holder-- for example, one model is "AA" size. Connecting an insulated size AA holder and using a size AA 3.6V battery is one way to handle BatRAM replacement now while making future replacements easier.

     Another Radio Shack 3.6V Tadiran Lithium battery comes as a small rectangular insulated pack with red and black wires going to a plug. From the catalog illustration, it appears that the plug could be fitted onto the cut- off leads if these were long enough to be shaped to match the plug's connectors. (If you decide to have long cut-off leads, it's a good idea to slip heat-shrinkable tubing over the leads to insulate them for most of their length.)

     It may be that your best bet for getting a good BatRAM replacement battery is All Electronics (800-826-5432; ).  Their catalogs often list 3.6V lithium batteries with and without wire leads in various sizes at low prices.

     If you like, you can always solder, crimp, etc. insulated leads going to some plug or socket which matches the connector of a particular battery you'd like to use. Whatever, make sure that the new battery's "+" lead connects to the "+" lead on the motherboard.

     For connecting solid wire bare leads, you can use the spring connectors from a Radio Shack electronics experimenter kit or just wrap the new battery's leads around a large sewing needle to make them springy. The springy leads can then be slipped over the cut off leads on the motherboard. Another non- soldering approach is to use "wire nuts".

     Should you do any soldering to the cut-off leads, use good quality rosin core solder (e.g 63 Tin multi-core) and try to avoid long heat exposure. You do not want to melt the connection at the motherboard. Similar concerns apply to soldering to the new battery leads. With good solder and clean leads it should be possible to "tin" each lead and make the connections in a few seconds for each operation.

     Especially if you are joining bare leads to bare leads, you could end up with more bare wire than you are comfortable with. Check that the bare leads do not touch anything they should not. Bend the leads as required and position the new battery so that nothing will bump into the Power Supply when it is replaced.

     The usual recommendation for this kind of work is that the computer be OFF. This reduces the risk of damage should a bit of solder, a wire, etc. fall onto the motherboard.

     When disposing of the old battery, snipping off its leads at the battery to reduce the chance of a direct short is a good safety measure. It's hard to be sure an old battery is completely dead; and, a direct short could produce enough heat to burst the battery and/or start a fire.

     GS users are sometimes shocked to discover that a replacement battery may cost $8 to $13. This has led to suggestions that 2-3 standard 1.5V cells in a holder be used. While any number of lower-cost replacement setups can work, this is pretty close to a classic 'you get what you pay for' situation. Regular 1.5V cell combos reportedly crater in about a year. A 3.6V 1.2AH Lithium battery is routinely good for at least 5 years.

     Our old Nite Owl battery is going on year 8 or 9. That's a lot of years without having to worry about burst and leaking cells or needing to pull the Power Supply and mess with swapping-in replacement cells.


From: Rubywand

Related FAQs Resource: (program in ShrinkIt file)

008- Is there a program to record my Control Panel, etc. settings
     and restore them after the GS BatRAM battery is replaced?

     Yes. A number of users have created programs to Save and Restore BatRAM values. The one included as a FAQs Resources file is named "BATRAMMER". It is in file After unzipping the downloaded file, use ShrinkIt or GS-ShrinkIt to unpack the file.


From: Adalbert Goertz

009- How can I safely clean out dust from my Apple II's
     motherboard, case, and expansion cards?

     I use a Dustbuster. Block one exit vent and aim the other vent as a blower into the computer. That Dustbuster has strong lungs!


From: George Rentovich

010- I'm afraid that oxidation on pins may be causing bad
     contacts and memory problems. How can I remove the
     oxidation without resorting to sand paper?

     Tarn-X works great for removing oxididation from chip pins without a lot of work or risk in harming the chips.

     Soak the chips in a shot glass until all black oxidation is gone; then, remove the chips and put them in another shot glass with alcohol to rinse. I use a third shot glass with alchol again to be sure and, then, take out the chips and let dry.


From: Rubywand

011- Recently I was using my GS and smoke started coming from the
     inside. Now my ADB peripherals (KB and mouse) don't work! It
     looks like the smoke came from an 8-legged module in the upper
     leftmost corner right behind the composite video connector and
     ADB jack. What's wrong? How can I fix my GS?

     The module you are talking about is L2 "D-15C". This is an 8-pin thing containing four inductors (coils). Three inductors are used. They are in series with the ADB Desktop connector. Evidently, one of the inductors burned out. This would explain the smoke and the loss of ADB functioning.

     The three inductors run ...

     pin 1 to  pin 8
     pin 2 to  pin 7
     pin 3 to  pin 6

     You can use an Ohm meter to detect which one is open. (Example: the correct reading from pin 2 to pin 7 would, probably, be less than an Ohm.) Since the pin2-pin7 inductor connects to +5V on the pin7 side, it is the best candidate for a burn out should pin2 some how have been shorted to ground.

Note: Jon Christopher reported that when his L2 module bombed it was due to a short in a spliced-on KB cable. It turned out that the resulting burn out fused some of the inductors together inside the module. So, if you detect any break after such a burn out, it is probably best to just remove the module and replace all three inductors.

     Replacing the inductors should be fairly easy, although it will probably be necessary to remove the motherboard. The value of the inductors is not critical, so 15-20 turns of small wire-- like wirewrap wire-- wrapped on a pencil or screwdriver shaft will make a small coil you can use. Make three coils.

     After removing the damaged L2 module, use an Ohm meter to check for a short to ground at pins 1, 2, and 3. (If, as in the case of a short in a spliced-on KB cable, you know where the short is/was, you can skip this check.)  Eliminate the short before continuing.

     Solder your home-brew coils in place (pin 1 to pin 8 for the first coil, etc.), put everything together, and your GS should be as good as new.


012- My ROM-01 GS has an odd postage stamp size circuit board
     tacked onto the motherboard near the front edge. What is the
     board for?

     The circuit on the mini-board is a low-gain 1-transistor amplifier which seems intended mainly as a buffer/voltage-level shifter between the 'old Apple' sound output of the Mega Chip and Op Amps which drive the Speaker and Sound jack.

     On the underside of the motherboard, beneath the boardlette, a surface- mounted resistor (SR1) has been scratched out. Leads from the mini-board run to SR1's connection points as well as Ground and a +12V supply point near Op Amp UM12.

     The circuit does not appear in the GS 'Hardware Reference ROM-01 schematics; but, it is shown in ROM-03 schematics. Some ROM-01 GS's do not have the mini board; so, it seems likely that the circuit was included on- motherboard in later ROM-01's and all ROM-03's. By the way, the circuit was certainly installed at the time of manufacture and was not part of the standard ROM-00 to ROM-01 upgrade.


013- I have 256kB on my 1MB Apple IIgs Memory Expansion Card.
     How do I add more memory and set the jumpers?

     The standard Apple IIgs 1MB Memory Expansion Card can be usefully configured for 256kB, 512kB, and 1MB.

     For 256kB, the top left 8 sockets (i.e. the left half of the top row) should be filled. No jumpers should be placed on the pins near the lower right end of the board.

                         O O (no Jumpers)
                         0 0

     For 512kB, the entire top row of sockets should be filled. The bottom pair of pins should be jumpered.

                         O O
                         0-0 Jumper bottom pair

     For 1MB, all sockets should be filled. The top and bottom pairs of pins should be jumpered.

                        O-O Jumper top and bottom pairs

     To get the full IIgs mem card upgrade to 1MB you can order a kit of 24 256k x 1 41256 DRAM mem IC's from Alltech (760-724-2404) for $24.00.


From: Supertimer

014- I've heard that some have moved their IIgs's to PC tower cases.
     Is this hard to do?

     It is not hard to do at all...

     I mounted the motherboard with the expansion cards going horizontal in relation to the ground (you need to drill some extra holes in the tower case because the GS has different mounting holes than the PC). The cards are light enough that they stay put this way.  The only time this could be a problem is with unusually heavy cards, like the Focus or MicroDrive units...

     The cards don't line up with the openings on the case, but that's not a problem because Apple cards, unlike PC cards, have ribbon cable extended DB connectors that can be mounted on the openings at the back of the case...

     For the power supply, I rewired a PC power supply to feed the GS. The voltages are the same, so simply match +5V with +5V, +12V with +12V, -5V with - 5V, -12V with -12V, and the grounds and your GS will be ready to run!

     The PC power supply (250 watts) and fans have a GS is more stable now than it was in its native case.  I recommend this upgrade for those who feel up to it.  Use a full tower case for the best results and most room to work with.


015- I recently picked up a spare GS from a flea market and
     would like to convert it into a portable. Has anyone done this?

     Yes. Tony Diaz has an article describing a couple conversions on his web site at .


From: Erick Wagner

016- Where can I get Robot kits to use with my Apple II?

     If you have a an RS-232 interface (2400 or 9600bps) you might consider a kit from Lynxmotion ( ). They sell various robot and robotic arm kits that utilize hobby R/C servo motors. Scott Edwards Electronics and several other companies sell devices that allow you to control up to 8 servos per board.

     You'll have to write all of the software yourself (sending commands to identify a servo and a position value).


From: Rubywand

     A good source of current information on robot making, Parallax BASIC stamp programming, and related projects is Nuts & Volts Magazine (800-783- 4624; ).

     A good on-line resource for BASIC Stamp components and info is the BSS Club at


From: David Chiu, Dick Pirong, Bart, Paul Grammens

017- Where can I get the "Zip" package chips to expand my AE GS-RAM III
     memory Expansion card to 4MB?

     The Applied Engineering GS-RAM III uses 20-pin "Zip" package 1M x 4 DRAMs (NEC D424400V-80 or OKI H5144024-70). A few other Apple II memory cards also use relatively rare Zip package RAM.

     As of November 2002, you could find the NEC chip at Spi Semiconductor (818-884-8000; ).  Search for 424400. For other suppliers, a fairly good try is a current issue of Computer Shopper magazine.

     Whenever you order these memory IC's, be sure to confirm that the chips are, in fact, in the Zip package.


From: Gilles Aurejac

018- What chip can I use to replace a bad RAM IC on my IIe

     The 4164 (64k x 1) works on motherboards using eight memory chips. The RAM on my motherboard is in sockets; so, it was easy to replaced a bad memory chip with one.


From: Rubywand

019- Could someone please post a resistor color code chart?

Color   Digit   Multiplier (when 3rd band)  Example

Black     0       x1              --  Red Red Black =         22 Ohms
Brown     1       x10             --  Blue Grey Brown =      680 Ohms
Red       2       x100            --  Orange White Red =    3900 Ohms
Orange    3       x1000           --  Yellow Violet Orange = 47k Ohms
Yellow    4       x10000          --  Red Green Yellow =    250k Ohms
Green     5       x100000         --  Orange Orange Green = 3.3M Ohms
Blue      6       x1000000        --  Red Yellow Blue =      24M Ohms
Violet    7       x10000000       --  ...
Grey      8       x100000000
White     9       x1000000000

Gold      -       x 0.1           -- Brown Brown Gold =      1.1 Ohms
Silver    -       x 0.01          -- Orange White Silver =  0.39 Ohms

Tolerance (4th band)

Red is           <5% (courtesy of Edhel Iaur)
Gold is           5%
Silver is        10%
no color is      20%

Example: Grey Red Orange Gold      is 82k Ohms  +/- 5%
Example: Brown Black Green Silver  is  1M Ohms  +/- 10%

Note: carbon resistors almost always err on the high side.


From: Mitchell Spector

020- What advantages does the ROM 3 GS offer vs. the ROM-01 GS?

     The ROM 3 Apple IIgs offers many minor enhancements vs. the ROM-01 which make the machine more functional and pleasant to use:

- You get a machine that is about 5-10% faster for GUI, floppy disk  loading and RAM Disk operations (due to updated smartport firmware  and System 5 tools being in ROM).

- A machine that is more flexible when working with AppleTalk and  slots (you don't have to give up an extra slot and you can stick a  card in slot 4 and still use the mouse in GS/OS).

- A nicer text Control Panel that lets you resize RAM Disk with a  warm-boot and a cleaner way to size it too (no min/max size junk).  Also a 'Mouse' menu and other existing things cleaned up and made  better.

- A just over 1 megabyte of RAM built-in to start off with; so, you  can have 5 MB of DMA compatible memory in total.

- The MB0 signal provided in slots 1 through 6, so you can stick  in a Video Overlay Card _and_ Second Sight in together, and not  worry about having to reserve slot 3.

- Hardware shadowing of text page 2 with Alternative Display Mode (no slowing down your system to a crawl when you see a screen full  of 2's running 8-bit software).

- A newer ADB keyboard microcontroller with built-in sticky keys,  keyboard mouse and compatibility with the indicator LEDs  on extended keyboards.

- A removable Lithum battery (in a snap case. Just pop the old one  out when your clock and Control Panel settings stop working).

- Less power consumption and electrical noise from the motherboard,

- A set of pins (location 'S1') on the motherboard to make the text  Control Panel disappear, making your GS settings tamper proof where  young children are around

    There are even a couple of more goodies, like the Step/Trace commands in Monitor or the improved disassembler. Even if you are not a programmer, they're handy for peeking at SHR graphics still in memory (from Monitor hit 'S' and then the return key).

    Things like sticky keys and mouse keyboard come in handy too-- like if you are eating or drinking with one hand, you can still reset the computer using the other.

    The down side is that some old GS games and demos won't run. However many of the more worthwhile ones have been patched.


From: Scott G

021- How can my ROM 3 GS + 8MB Sirius card do large file copying?

     An error in the Sirius manual (a 1 page paper) recommends that ROM 3 users remove one of the SIMM modules since the ROM 3 has 1MB and 8MB is max. When I did this, the GS reported 8MB, but copying large groups of files or large files (>800k) failed.  When I put the missing SIMM back, the GS still reported 8MB, but the file copy problems vanished.  It appears that the Sirius needs eight 1MB SIMM modules for 8MB even on a ROM 3.


From: Rodney Hester

     Turns out I had the opposite experience. In my system (ROM 3 with 8MB Sirius v2.0 and Focus drive) the large file corruption problems, "ghosties" (weird video artifacts), random system crashes (especially when Balloon 2.0 was active), etc. _all_ went away when I _removed_ "SIMM 8". (There is some numbering on the back of the Sirius.)


From: Supertimer

022- I just received my Sirius RAM card and populated it with
     8 1MB SIMMS. However my ROM 3 GS crashes early in the boot
     process. Could it be a problem with my RamFAST and DMA?

     First, if your RamFAST is the Rev. C (full-length) card, it cannot DMA to 8MB; so, you will have to turn DMA off. The Rev. D can DMA to 8MB fine.

     Second, make sure there are 8 SIMMs on the Sirius. Alltech used to say that you are supposed to take out one of the SIMMs when using the 8MB Sirius card on a ROM 3; but, this leads to problems.  Plug in all 8 SIMMs and use it that way. You lose the 1MB from the motherboard this way, but you gain it back on the 'extra' SIMM you put in.


From: David Wilson

023- I have several different model Apple II computers ranging from
     a II+ up through a IIgs. Does anyone know where I can get
     diagrams for these machines?

     I know of three books with Apple ][+ schematics:

     Jim Sather's "Understanding the Apple ]["

    "The Apple II Circuit Description" by Winston D. Gayler
      published by Howard W. Sams & Co (ISBN 0-672-21959-X)

     Apple II Reference Manual (1979)


From: Charles T. Turley

     A set of IIgs ROM-01 schematics was published in the September 1999 issue of GS WorldView.  Go to GSWV's Archive at ... .


From: Rubywand

     The Apple II Reference Manual (1979) includes a II/II+ schematic, a keyboard schematic, and annotated firmware listings. For Disk II and Disk II Controller schematics, see The DOS Manual (1981) from Apple.

     For the IIe and enhanced IIe, see the Apple IIe Technical Reference Manual. The 1986 edition includes diagrams and annotated firmware listings. 

     The Apple IIc Technical Reference Manual (1987) includes IIc schematics and firmware listings for the three major IIc versions. A later (1989) "Second Edition" of the manual includes IIc+ coverage.

     The Apple IIgs Hardware Reference has a good set of schematics. The First Edition covers the ROM-01. The Second Edition covers ROM-01 and ROM 3. Unfortunately, there is no IIgs firmware listing.

     Although most Apple II manuals are out of print, many can still be purchased from on-line book sellers such as

     On-line, GS Worldview's archive offers a couple folders with several schematics at .


From: David Empson

024- I just got a Dallas Smartwatch (aka No Slot Clock) for
     my Apple IIc+. Where does it go?

     There is only one ROM in the IIc+: it is probably 32KB in capacity, like the UniDisk revision of the IIc and later IIc models, hence it would be a 28 pin chip.

     Assuming the SmartWatch works in the IIc+ (and I don't know of any reason why it wouldn't), you need to put it under the chip labelled "Monitor ROM". Make sure you get it around the right way!

     One other point: I hope you got the right variety of the SmartWatch. The part number should be DS1216E.  The letter suffix indicates the type of chip which the SmartWatch works under, with "E" being a 28-pin ROM. The suffix should be printed in the form of a large green letter (silk screened) on the small circuit board which is visible beside the DS1216 chip inside the SmartWatch.


From: Charles T. Turley

Related FAQs Resource: R023PINOUTS.TXT (text file)

025- Where can I find Apple II socket, etc. pinouts?

     See the FAQs Resource file R023PINOUTS.TXT.


From: Adalbert Goertz

026- What IC do I need to use the GS-RAM Plus in my Apple IIgs?

     You need the GSPLD1A.1 for a ROM-01 GS and the GSPLD1B.1 for a ROM 3 GS.


From: Rubywand

027- Where can I get prototyping boards that fit Apple II Slots?

     The standard Apple II Slot card has 50 contacts, 25 per side, and is up to 2.75" high (not counting contacts). Contact spacing is 0.10". Length varies. About 0.50" of the length can extend beyond the contacts toward the back of the computer.

     You may be able to find an 'Apple II prototyping board' from a surplus parts seller; however, these boards are no longer a standard item. To get a new board, you will probably have to get a PC ISA-8 ("PC XT") Slot board (or an ISA-8/16 Slot board with the extra contacts trimmed off).

     An ISA-8 board has 31 contacts per side spaced the same as an A2 card. From the edge facing the front of the computer, you will need to count down and trim away 6 contacts (per side). It's best to use a real A2 board as a guide to determine pin centering and to decide what to slice off for a good fit in an Apple II Slot. A Dremel tool with a sand wheel is good for this sort of slicing.

     The best deal I've found on proto boards for Apple II Slot card projects is the 9003 PB from Marlin P. Jones (still offered as of Feb 2004).  It's a good length for most applications (5.6") and costs $7.95. The 9003 PB is 4.25" high; so, you will need to cut off about 1.5" from the top to get a fit in most Apple II's.

     Another approach to getting an A2 prototype board is to 'clean off' and reuse a surplus A2 card. Or, you can slice off the connector pins (plus a bit extra) from some surplus A2 or ISA-8 PC board and bolt the connector to a common rectangular proto board.


From: Patrick Schaefer, Quadrajet1, David Empson, 
      David Wilson, Rubywand 

028- What are the numbers and functions of major Apple II ROMs? 

341-0001-00*    Integer BASIC E0                                1978 
341-0002-00*    Integer BASIC E8                                1978 
341-0003-00*    Integer BASIC F0                                1978 
341-0004-00*    Integer BASIC F8 (Old Monitor ROM)              1978 
341-0009        13 Sector drive controller P5 ROM 
341-0010        13 Sector drive controller P6 ROM 
341-0011-D0*    Applesoft BASIC D0 
341-0012-D8*    Applesoft BASIC D8 
341-0013-E0*    Applesoft BASIC E0 
341-0014-E8*    Applesoft BASIC E8 
341-0015-F0*    Applesoft BASIC F0 
341-0016-00*    Programmer's Aid #1                             1978 
341-0020-F8*    Applesoft BASIC F8 (Autostart Monitor ROM) 
341-0027        16 Sector drive controller P5 ROM 
341-0028        16 Sector drive controller P6 ROM 
342-0033-A      //c Monitor ROM $00                             1985 
341-0036        ][plus character ROM 
341-0065-A      Super Serial Card                               1983 
342-0077-A      IIGS ROM-00
342-0077-B      IIGS ROM-01                                     1987 
341-0080-B      ProFile 5MB RW-Z8                               1981 
341-0112-A      Apple SCSI (non-HS) revision A firmware 
341-0112-B      Apple SCSI (non-HS) revision B firmware 
341-0124-A      IIGS Keyboard i8048 
342-0132        IIe (and //c) Keyboard ROM (USA)                1982 
342-0132-A      IIe (and //c) Keyboard ROM (USA)                1982 
342-0132-B      IIe (and //c) Keyboard ROM (USA) rev DVORAK, pad
342-0132-C      IIe (and //c) Keyboard ROM (USA)                
342-0132-D      //c Keyboard ROM USA                            1984 
342-0133-A      IIe Video (Char Gen) ROM                        1982 
342-0134-A      IIe EF ROM                                      1982 
342-0135-A      IIe CD ROM                                      1982 
342-0135-B        "   (identical)                               1982 
341-0150-A      IIe Keyboard ROM UK/usa                         1982 
341-0151-A      IIe Keyboard ROM deutsch/usa                    1982 
341-0160-A      IIe Video ROM UK/usa                            1982 
341-0161-A      IIe Video ROM deutsch/usa                       1982 
341-0265-A      //c USA Char Gen                                1983 
342-0272-A      //c Monitor ROM $FF (original)                  1983 
342-0273-A      //c, //e (enhanced) Char Gen UK
342-0275-A      //c, //e (enhanced) Char Gen deutsch            1983 
342-0303        //e (enhanced) EF ROM
342-0304        //e (enhanced) CD ROM
342-0349-A      //e (platinum) CF ROM
342-0372-A      //e (enhanced) KB ROM deutsch/usa               1985 
341-0437-A      Apple SCSI (non-HS) revision C firmware 
342-0445-A      //c Monitor ROM $03 (memory expandable)
341-0625-A      //c plus Monitor ROM $05                        1988 
341-0728        IIGS ROM  3 FC-FD (prototype)
341-0729        IIGS ROM  3 FE-FF (prototype)
341-0737        IIGS ROM  3 FC-FD                               1989 
341-0748        IIGS ROM  3 FE-FF                               1989 
341-0749        IIGS ROM  3 FE-FF (prototype)

* Note: Use of "-00", "-DO", etc. suffixes (or no suffix) 
seems to vary radomly. For instance, an E8 ROM might be 
numbered 341-0014 or 341-0014-00 and have "E8" stamped 
elsewhere on the ROM. 

In most cases, this also seems to apply to "-A", "-B" 
suffixes (or having no suffix). 


From: Rubywand 

029- What is the C-One?

     The C-One is a modern (2003) 65816-based motherboard designed to fit in a standard PC ATX case. Promoted as an "enhanced adaptation of the Commodore 64", C-One's 20MHz uP, advanced graphics and sound, I/O, and other capabilities has attracted the attention of Apple II users as the model for a similar-design Super IIgs. (ref: "C-One Page" in the FAQs Major A2 Sites listing.)


From: George Rentovich, the guys on the English Amiga Board, Rubywand

030- My Apple II's case, mouse, and keyboard have been discolored by years of
     exposure to sunlight, UV, etc.. How can I re-whiten them?

     Years of exposure to sunlight and other UV can result in yellowing or even browning of Apple II cases. One solution is to pick a color and paint the case via a few light coats of a spray paint. If you want to restore the original color, you can get a good match using Apple II pictures available on the net.

     A recently discovered alternative to painting is bleaching out the discoloration using hydrogen peroxide (H2O2). According to claims, the process described here does not damage painted labels, metal inserts, etc. except as they may be attached by a water soluable adhesive.

Note: Most of the info here comes from the English Amiga Board at .

What You Need

- Hydrogen peroxide (H2O2)- water added as necessary to get desired

- Vanish Oxy Action or Oxi Clean Versatile Stain Remover or pure
  TAED (Tetra Acetyl Ethylene Diamine)-- don't need much

- UV 'Blacklight' bulb (60 watts or so) in a lamp (indoors) or sunlight
  Note: Do not use other UV sources, such as germicidal lights.

- Plastic or glass container (possibly with a transparent cover)

- Bostik Blu-Tack or similar reusable adhesive to help hold small parts in

- Water close by, such as in a large bowl, for washup and washing off cleaned

- Rubber gloves

- Full Protection Goggles. You only get one pair of eyes!

- Tongs may be helpful for retrieving smaller parts

WARNING: Do Not even think about mixing in chlorine bleach with the H2O2! 
The result could be to release chlorine gas.

Hydrogen Peroxide Mixture

     Hydrogen peroxide(H2O2) comes in two well-known forms: stable and unstable (rocket fuel) determined mainly by concentration. The highest concentration which is commonly available and which is allowed for postal shipping is 35%. H2O2 in useful strengths is available in various forms and concentrations from several sources including chemical sellers, cleaner makers, and hair product sellers.

Note: Sometimes H2O2 concentration is expressed in "volume". A peroxide product for hair bleaching may be labeled "40 Volume". To get the % concentration, you divide by 3.3. 40 Volume = about 12% H2O2. 

     H2O2 specified as "not less than 20% nor more than 40%" is available in a gallon size as a cleaning product called "Urine Rescue" by Prochem for about $15/gallon. You can obtain 12% H2O2 (such as "Super Star 40 Volume Clear Peroxide Gallon" for $7.77/gallon) from various hair salon sellers. 

     The higher the strength, the speedier the whitening. However, at 35% you have a more hazardous solution (e.g. in terms of skin/eye splashes) and will need to monitor the process more closely to avoid etching of the plastic. 

     Another factor is that the H2O2 you use will probably not retain its whitening properties for more than a few days. If you use lower concentrations you can stretch out your H2O2 supply over more cleaning sessions. A good balance of speediness, hazards, and cost is around 20% H2O2. 12% is fine, too; but, slower. Whatever your concentration, you will need enough to keep the item being whitened wet during the process.

     Plain H2O2 is not particularly speedy as a whitener below roughly 100 degrees F. So, to activate the H2O2 a small amount of TAED (Tetra Acetyl Ethylene Diamine) is added at the start of the process. One popular cleaning product containing TAED is Oxi Clean. About 1/4 teaspoon per gallon of H2O2 solution is enough.


     This process requires UV light on the surfaces you wish to whiten. (This can come from the sun or a blacklight bulb.) Whatever container you use needs to keep the plastic in the solution and allow light to reach the surfaces. Since the process does generate some heat it is best to avoid using exceptionally flimsy plastic containers.

     Some smaller parts may tend to float due to build up of gasses in gaps and recesses. A reusable adhesive gum, like Blu-Tack, can hold them in position in the tank so that keytops, etc. stay emersed in the solution and get light.

     The container, tank, etc. needs to be out of the reach of small children and pets. Be sure to let older children and anyone else who may be able to reach the container know that the stuff inside is not plain water and is hazardous. Place warning signs/notes on or near the container. 

     If outside using sunlight, use a transparent lid or similar covering to keep out birds and insects.

Some Hazards

     The main hazard from H2O2 is probably to eyes. Wear full protection goggles and have plain water available for flushing eyes or skin in case of contact with H2O2.

     Another hazard is the oxygen given off during the process. At higher concentrations oxygen can ignite from electrical sparks, candles, etc.. The place where you do the process should be well ventilated.

     The UV light to be used for indoor work is 'blacklight' UV. It is sometimes used to highlight posters in darkened rooms. (Other UV sources, such as various germicidal lights, can be more hazardous to vision.)  It is best to avoid long exposure-- i.e. do not stare at the lighted process for extended periods. 


1- Thorougly clean the item(s) to be whitened with soap and water.

2- Set the container for the cleaning process in a safe area out of reach of
   small children and pets.

3- Place the item(s) in the container. If KB keys or similar small items are to
   be cleaned, you may want to stick them in place with Blu-Tack, etc.. 

4- Put on goggles and gloves. 

5- Pour in the H2O2. Add water to get desired concentration. Do not fill to
   brim. Allow some room for foaming activity.

6- Add 1/4 teaspoon of an 'Oxy' cleaner or pure TAED per gallon of
   H2O2 solution. (Expect some foaming action.)

7- If indoors, turn On your blacklight(s). Check that surfaces to be whitened
   are getting light.

8- Every hour or so check the progress of the whitening. Time required depends
   upon many variables. It may be a few hours, several hours, or a few days.

9- When whitness is satisfactory, remove the part(s). Wash or submerge in
   plain water and dry.

The Gel Option!

     In order to simplify whitening larger items such as cases, the EAB guys have developed an H2O2 gel which can be brushed on.

     Here's a quickie summary from a posting by Merlin ...


 1 pint Hydrogen Peroxide, at least 20% strength
 1 teaspoonful xanthan gum (health food shops or Ebay)
 1/2 teaspoonful Vanish Oxy Action Plus (any 'Oxy' laundry booster will do)
 1 teaspoonful glycerine


 Gloves and Goggles (Safety First!)
 1 UV blacklight lamp
 Liquidiser or hand blender


Chuck all ingredients except the Oxy into a container and mix until a 
smooth thick gel is formed. 

Just before you use it, add the Oxy in by stirring and then brush the
mix onto the item to be treated. Stick it under the UV lamp.
Check regularly until the yellowing has gone.


Take care!

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