A1200 Hardware Frequently Asked Questions
Version 2.0
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Copyright (C) 1996 by Warren Block.
Distribution
------------
This document is freeware. It has been copyrighted to assure its availability
to everyone. Fred Fish and the Aminet are explicitly allowed to include this
document in CD-ROM or floppy compilations; others should ask first. Please do
not modify this file without permission.
Disclaimer
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The information contained herein is a crock. It's full of dangerous errors,
omissions, and outright lies, and is not guaranteed to do anything other than
take up disk space. Not for internal use. Keep out of reach of demo coders.
Introduction
------------
After putting together a much fancier document for the A4000 (the Amiga 4000
Hardware Guide), it was suggested that something similar was needed for the
A1200. Additionally, I kept seeing the same questions asked over and over in
comp.sys.amiga.hardware, and it seemed like a FAQ might help both those
asking and answering the questions. Maybe it'll just change all the answers
to say "Read the FAQ, you moron." Nah. Amiga people are more polite than
that. They'd say "PLEASE read the FAQ, you moron."
Introductory Questions
----------------------
Q. I have a problem with my A1200. Can I email or call you for help?
A. I'd rather you ask any questions that aren't answered here in a public
forum in comp.sys.amiga. That way, you can draw on more experience than
just my own (which is admittedly somewhat limited with the A1200), and the
answers can benefit others with similar problems.
Q. Hey! You left out many details on some of these topics.
A. That was intentional; some of these answers have been simplified, both to
keep this document relatively short, and to avoid confusing the issues.
Please remember that this is an introductory document, and not a technical
reference guide, and is intended merely to answer the most common
questions. So there. Nyah.
Q. Hey, FAQ boy, you screwed up, and some of this information is wrong, or
you just didn't include something that was completely obvious! Can I send
you email with the correct information?
A. Yes, please do. I am:
Warren Block
602 St. James
Rapid City SD 57701
(605) 342-1632 Voice
wblock@rapidnet.com
Thank you for your interest, and good luck with your A1200!
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Power Supply
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Q. Is the stock A1200 power supply adequate for an accelerator, extra RAM,
and bigger hard disks?
A. Probably not. The stock supply is only rated at 23 watts. While you may be
able to get the computer to boot with expansion hardware, it may not
operate reliably.
Q. I want to build a "super power supply" for my A1200. What are the pinouts
of the power supply connector?
A. Look on the power supply itself, where the pinouts are usually specified.
Q. Can I use an Amiga 500 or Amiga 600 power supply with my A1200?
A. Yes. The connectors and voltages match perfectly.
Q. What about the higher watt rating of the A500 supply? Won't all that extra
power melt and/or blow up my A1200?
A. No. The watt rating of a power supply only describes the absolute maximum
amount of power it can supply. The A1200 will only draw as much of this as
it needs to operate.
Floppy Drives
-------------
Q. Can I use an IBM high density drive on an A1200?
A. Not easily, simply, or reliably. There are some hacks that allow this,
but, as of this writing, they all still have problems, and can be
considered experimental. If you're determined to try, there are several
plans in the hard/hack section on Aminet. An easier solution is to
purchase one of the commercially-available high-density drives from an
Amiga dealer.
Q. Can I read and write Amiga diskettes on a PC clone?
A. No. The floppy controller hardware on most clones is incapable of reading
or writing the Amiga disk format. To transfer files on disk between a PC
clone and an A1200, use 3.5-inch double-density floppies formatted in the
720K MS-DOS format. The A1200 can read and write these using CrossDOS
(included with AmigaDOS 3.0).
Q. Can I use high-density floppies with the A1200's normal disk drive?
A. Not reliably! The high-density disks need a stronger magnetic field from
the disk heads to reliably write to them. A high-density drive does this
automatically, but the A1200's double-density drive can't. Writing
high-density disks with a double-density drive will result in erratic
operation of those disks. They may work fine for hours, days, or weeks,
only to fail when you need them most. Use double-density disks with Amiga
double-density (880K) drives, like the one built into the A1200, or get an
external or internal high-density Amiga drive.
Hard Drives
-----------
Q. Why doesn't my A1200 boot off the hard drive when I first turn it on?
A. Many hard drives don't spin up fast enough to be ready when the A1200
is ready to boot. If you can reset the A1200 after it comes up with the
purple "insert floppy" screen and it will then boot from the hard drive,
this is the case. The easiest solution is to just live with it and reset
the machine when you first turn it on. If this really bothers you, you
could replace the drive with one that spins up faster. Alternatively,
AmigaOS 3.1 (if your A1200 doesn't already have it) has a longer IDE drive
delay.
Q. When I first power-up my A1200, the hard drive works fine, but after a
reset the hard drive is no longer recognized. What's wrong?
A. This is a problem with the way the drive handles the IDE reset signal. The
easy fix is to cut pin 1 on the IDE cable (usually the one with the
stripe), peel back the wires a little, and tape them off, disconnecting
the reset signal. This problem is commonly reported on Conner hard drives
(although I don't feel it's a significant flaw).
Q. How hard is it to install a hard drive inside my A1200?
A. It's not hard. You need a few things: a 2.5-inch IDE hard drive (commonly
used for notebook computers), a short section of special 44-pin ribbon
cable to fit the drive (this cable is spaced more tightly than normal
ribbon), and, preferably, the Commodore Install disk. First, you install
the drive, then use the Install disk to partition it and place the system
software on it. That's it. The toughest part is obtaining the Install disk
and the special cable.
Q. Should I low-level format the hard drive?
A. No. On both IDE and SCSI drives, an initial low-level format has been
performed at the factory. You should never need to low-level format them
again. After partitioning, you *do* need to "high-level" format a hard
drive with the AmigaDOS Format command; when used with hard drives, you
can specify the QUICK keyword with the Format command to speed up this
high-level formatting immensely.
(Example: Format drive dh2: name "Sample" quick noicons.)
Q. Can I use a 3.5-inch hard drive inside my A1200?
A. Yes, but be warned. Physically, it can be made to fit; but problems can
arise from the extra power consumption of the 3.5-inch drives, coupled
with the anemic stock power supply of the A1200. Obtaining a cable to
adapt the 44-pin high-density IDE cable to the 40-pin normal-density IDE
connector can be difficult, too. Electronically, they are compatible. See
the hard/hack directory of Aminet for projects.
Q. Can I use an "EIDE" or "Fast ATA" hard drive with the A1200?
A. Yes. These drives are merely refined IDE drives.
Q. Will large-capacity (500M and up) drives work with the A1200?
A. Yes. The 500M capacity "limitation" originates from the PC clones, and is
only a problem with them. For the Amiga, you can safely go up to a 4G
(~4000M) hard drive, provided you can find (and afford) one that large in
a 2.5-inch IDE or EIDE format.
Q. What is MaxTransfer?
A. MaxTransfer is a value (set in HDToolBox) that limits how much data can be
transferred to or from the hard drive at one time.
Q. Why is MaxTransfer needed? Shouldn't the drive move as much data at one
time as possible?
A. Yes, it should, but some hard drives have arbitrary limits on how much
data they can move at one time. On the Amiga, if you have problems
transferring files of 128K or larger to or from the hard drive, this is a
likely cause of the problem.
Q. I have have no idea what the MaxTransfer value should be for my drive.
What value should I use?
A. For unknown drives, the maximum "safe" value is 0x0001FE00. Other (older)
drives may require 0x0000FFFF or even 0x0000FE00. The sure test is to copy
files larger than the MaxTransfer value to and from the drive, checking
for corruption afterwards. IFF pictures work well for this, as corruption
is easy to see.
Q. Will this low MaxTransfer value slow down disk transfers?
A. Very little or not at all. Most disk transfers are smaller than 128K, and
so this setting will not affect them. But don't take my word for it; use
DiskSpeed and test it yourself.
Q. What is Mask?
A. Mask is a value (set in HDToolBox) that determines what type of memory
(Chip or Fast) can be used to buffer data transfers to or from the hard
drive. Unless you have a good reason to change it, leave it at the default
setting in HDToolBox.
Q. What 2.5-inch IDE hard drives are known to work with the A1200?
A. Most do, although you may have to adjust the MaxTransfer value (see
above). I personally dislike the Seagate drives included with many A1200s
(I consider them the Kraco of hard drives), but they work fine for many
people. My own Toshiba works fine, although, like many drives, it has the
"slow spin-up" problem.
CD-ROM Drives
-------------
Q. What SCSI CD-ROM drives work with the A1200?
A. First you need a SCSI interface, like the Dataflyer SCSI+, the SCSI
interface built into certain accelerators, or a PCMCIA SCSI card like the
Squirrel. Some SCSI controllers have been reported to have trouble with
certain drives, but in general, the Apple CD300 (which is a Sony drive),
Toshiba, and NEC drives have been reported to work well with the Amiga.
Personally, I can verify that the NEC 3Xe works fine with the SCSI+
interface.
Q. Can an EIDE CD-ROM drive be used with the built-in IDE of the A1200?
A. Yes, provided the drive is a true EIDE drive. Most non-SCSI CD-ROM drives
are not IDE, but a "sort-of" IDE. Newer drives are EIDE, and these can be
made to work on the A1200. It requires an ATAPI driver (a demo version of
one is available on Aminet) and the 44-to-40-pin adapter cable. My
opinion: SCSI gives you much more for your money, because you can use the
SCSI bus for other things in addition to CD-ROM drives. Some accelerator
boards have SCSI ports, offering an all-in-one solution.
Q. What software do I need to access a CD-ROM drive?
A. Frank Munkert's excellent AmiCDROM filesystem, or the one that comes with
AmigaDOS 3.1. AmiCDROM works extremely well on both ISO 9660 and HFS
(Macintosh) CD-ROM discs, and it's free. Look for it on
Aminet: disk/cdrom/AmiCDROM-1.15.lha.
Q. I need more information on CD-ROM disks, drives, and interfaces,
especially as they relate to the Amiga. Where can I look?
A. There is an excellent overview of the subject by Joachim E. Deu�en on
Aminet. Look at the file docs/help/CDROM20.lha.
Processors
----------
Q. What is the 68EC020 processor that comes inside the A1200?
A. It is an inexpensive version of the 68020, in a Plastic Leaded Chip
Carrier (PLCC) package. The only electronic difference between this
processor and the 68020 is that the EC version only brings out signals
for 24-bit addressing. Internally, it is fully 32-bit.
Q. What's the difference between the 68EC030 and 68030 processors that come
with accelerator boards?
A. The two are physically the same, with the difference being that a 68030
has a functional Memory Management Unit built into it, which the EC
("Embedded Controller") version lacks. The MMU is useful for programmers
(for debugging purposes), allows running Unix systems like NetBSD, and
also can be used to remap Kickstart code, allowing the system to run
faster (in some cases--this depends on the individual system, accelerator
board, and memory).
Q. Are there any 68040 or 68060 accelerators for the A1200?
A. Yes, there are several. A 68060 is desirable, since it'll generate much
less heat inside the A1200 case. Other features to look for are SCSI
interfaces and more than one SIMM slot.
Q. Can I replace the 68EC020 that comes with the A1200 with a full 68020?
A. Not directly, no. The 68EC020 is soldered onto the A1200 motherboard, and
even if it weren't, the 68020 differs physically from it. The best way to
perform this upgrade is with one of the many inexpensive accelerator
boards.
Q. Can I replace a 68EC030 with a 68030 with an MMU?
A. Yes, as long as they're physically the same. Some 68030s are Pin Grid
Array (PGA) packages, and some are Plastic Leaded Chip Carrier (PLCC).
With the PGA type, you can carefully and gently pry the old chip out of
the socket and then replace it with the new one. Some PLCC chips may be
soldered down, some may be in sockets. If it's in a socket, yes, you can
replace it, but you should get the proper removal tool to avoid breaking
the socket.
Memory
------
Q. What do I need to expand the memory of my A1200?
A. You'll need either a RAM board or an accelerator board, either of which
will fit into the trap-door expansion port on the bottom of the A1200, and
will have sockets for memory expansion. Please note that some expansion
boards made by GVP use custom SIMM modules, which are hard to find and
much more expensive than standard 72-pin SIMMs.
Q. My accelerator or RAM board has one or more 72-pin sockets for memory
SIMMs. Can I use 72-pin SIMMs meant for PC clones?
A. Yes. Read on for more details.
Q. Some 72-pin SIMMs are 36-bit and some are 32-bit. Is this related to
"parity," and which do I need to use with the A1200?
A. PC clones use extra "parity" bits for double-checking memory. On the
A1200, these extra bits will simply be ignored, causing no problems. The
extra four bits on the 36-bit wide SIMMs are these parity bits. The 32-bit
wide SIMMs are usually meant for use on the Macintosh, which, like the
Amiga, don't use parity. Summing up: 36- or 32-bit wide SIMMs--which is
just another way of saying "with or without parity bits"--will work for
accelerators or RAM expansion boards with 72-pin SIMM sockets.
Q. I've seen SIMMs with speed ratings of 60, 70, and 80 ns. What does this
mean, and which do I need?
A. These numbers rate the speed at which the SIMM can be reliably operated. A
60 ns SIMM is the fastest currently available at reasonable prices. To
keep a processor running at its fastest rate, the memory needs to be able
to keep up with it; the speed of your processor determines the minimum
memory speed needed. For an A1200 with just a RAM expansion board, 80 ns
SIMMs are fast enough. With an accelerator, it depends on how fast the
processor is going, so you'll need to check the manual. (Note: many boards
let you use slower SIMMs with them by enabling a "wait state," which
forces the processor to slow down to the SIMM's speed, and allows you to
use cheaper SIMMs. For instance, an accelator may say that it requires 70
ns SIMMs to run at "zero wait states," but will operate with an 80 ns SIMM
(slower) if you set a jumper to enable a wait state.)
Q. If I get faster SIMMs than I need, will it make the computer run faster?
A. No. This is a common misconception. The processor determines how fast the
memory needs to be, and will not run any faster even if the memory is
capable of it. For instance, if your accelerator needs a 70 ns SIMM, and
you use a 60 ns SIMM, it will not run any faster than it would with a 70
ns SIMM. (It may be a good idea to buy faster RAM than you need, though,
since you could then use it with a faster processor in the future.)
Monitors
--------
Q. I have a VGA or SVGA monitor from a PC clone. Can I use it with the A1200?
A. Maybe. The "double" video modes of the A1200's AGA chipset provide video
frequencies of 23 kHz and up, and will work with many VGA monitors.
However, true PC clone-type VGA operates at a frequency of 31.5 kHz, and
some monitors won't operate at frequencies much lower than that. The "VGA
Only" monitor driver may be used to raise the A1200 output frequencies,
making them high enough to be recognized by some monitors. You should
certainly try any VGA monitor before you buy it, though, just to be sure.
(Note: many games and some system software operate only at 15.75 kHz. For
instance, the configuration screen you get by holding down the mouse
buttons during a reset only displays at 15.75 kHz, and will not be visible
with a VGA-type monitor. However, there is some software that addresses
this; look at the Aminet file gfx/aga/AAStarter12.lha.)
Q. What specifications does a multisync monitor need to work with the A1200?
A. Ideally, you need it to have a sync range from 15 kHz to 31.5 kHz or
higher. Digital presets are very helpful because they allow you to set
screen size and centering for all the different screen modes.
Q. Where can I get an adapter to go from the A1200's DB23 video port to the
goofy high-density HDD15 standard VGA connector that looks like a DB9?
A. The adaptor that comes with an A4000 can be used, or you can get a wiring
diagram from Aminet: hard/hack/ami2vga.lha. Alternatively, you could have
Redmond Cable build one for you (call them at 206-882-2009).
Q. Can I use a CGA monitor with an A1200?
A. Yes, but it won't work particularly well. CGA is digital RGB, so it can
only generate 16 predefined colors. If it's the only monitor you have, you
can probably live with it, but I would personally recommend even a
composite video monitor instead (the old 1702 would work well for this).
Q. What Commodore monitor should I buy for use with the A1200?
A. My opinion: Don't buy any Commodore monitor. There are several monitors
like the Microvitec 1438 and 1440 that are marketed specifically use with
the Amiga (these are also resold under the Amiga Technologies label), and
there are general-purpose VGA-type monitors that also work well. In most
cases, these monitors are less expensive, better made, and more reliable
than those that were sold by Commodore (which were OEMed from monitor
manufacturers anyway). If you're looking for something inexpensive that
will work with all the frequencies and output modes of the A1200, see if
you can locate a used Mitsubishi DiamonScan (AUM 1381A) or NEC 3D. These
monitors are quite cheap now, and will handle all the RGB output of the
A1200 (the Mitsubishi also has a composite video input). If you're buying
something new, I strongly recommend a monitor with digital presets, which
makes screen adjustments much easier and eliminates the need to fiddle
with knobs every time you change screen modes (the Microvitec 1440
mentioned above is reported to have digital presets).
Other Questions
---------------
Q. I don't like to shut off the A1200 to connect and disconnect joysticks,
modems, video and sound samplers, and printers. Can I damage the A1200 by
changing these connections with the power on?
A. Yes. Remember that the A1200 design uses chips that are almost all surface-
mount, soldered directly to the circuit board. This makes it very
reliable, but when you expose it to dangerous behavior (changing
connections with power applied), you risk damaging chips that are very
difficult to replace and extremely difficult to obtain. Before you switch
cables, make sure that power is off to the entire system, including the
peripheral you are connecting or disconnecting.
Q. Is there a way to get a battery-backed clock into the A1200 without buying
an expensive expansion board?
A. Yes. There is a header on the A1200 motherboard specifically for adding
one of these inexpensive clock boards, which usually cost less than $30
US. However, a RAM expansion board with a clock is usually only about
double that, and gives you the ability to add 32-bit expansion memory
later, which will approximately double the operating speed of the A1200.
Q. Can I modify the A1200 to have a remote keyboard?
A. Yes, if you're really motivated. There is a file on doing this in the
hard/hack section of Aminet. It is non-trivial.
Q. Can I remount my A1200 in a PC tower case?
A. Yes, although it'll be a lot of work, and no warranties. See the hard/hack
section of Aminet.
Q. Can the A1200 be upgraded to AmigaOS 3.1?
A. Yes. The operating system ROMs are socketed, and several places are now
selling versions of 3.1 that are specifically made for the A1200. In fact,
the new A1200s being sold by Amiga Technologies come with 3.1.
Q. Is there an adapter box that lets me use Zorro boards on the A1200?
A. There are supposed to be several, although details are scarce, mainly
because these things are quite expensive and therefore rare. Don't count
on being able to use any given card with them; the A1200 was not designed
for this type of expansion and bus noise and other problems are bound to
make using some boards problematic.
Q. Can I use a Video Toaster with the A1200?
A. Normally, no. Some expansion boxes claim to add a video slot, although
whether this will work with the Toaster is unclear. There are video
digitizers and genlocks available specifically for the A1200, though.
Q. Is there a Mac emulator for the A1200?
A. There are two at present: ShapeShifter and Emplant. ShapeShifter is a
shareware package that can be downloaded from the misc/emu directory of
Aminet, while the A1200 Emplant is a commercial software package.
Either emulator will require a legal Mac ROM, although which versions they
support or require may vary with the release version. You'll also need the
Macintosh operating system. Version 7.5 can be purchased from Macintosh
dealers, or you can download an earlier release from Apple's web site.
Q. Is there an internal jumper on the A1200 to set it to default to PAL or
NTSC video?
A. No, but if you're really motivated, you can rig this up. My thanks to
Tetsuo Oda and Byron Montgomerie, who provided the information that
connecting pin 41 of the Alice custom chip to ground causes the A1200 to
default to NTSC, while pulling this pin high (disconnecting it from the
motherboard and connecting it to +5V through a 4.7k resistor) will make
the default power-up state PAL. I would point out that making a
modification like this on a surface-mount chip is difficult at best, and
you may end up needing an expensive motherboard replacement, or, at worst,
a dead A1200 with no replacement motherboard available. In most cases,
using the boot menu (obtained by pressing both mouse buttons on power-up
or reset) to switch to PAL is sufficient. However, with some games, the
hardware patch will be necessary to insure proper timing (changing to PAL
via the boot menu might make a 50 Hz game run at 60 Hz timing, or vice
versa).
Conclusion
----------
Will Paula meet the blitter of her dreams? Will Akiko ever get together with
Fat Agnus? And what is the mysterious PCMCIA Corporation planning in their
corporate headquarters at 68030 DMA Drive? Tune in next week...