ICD AdSpeed User manual

OwnersManual
Advanced 68000 CPU
Accelerator for Amiga
Computers

Table of Contents
Introduction......................................................................................1
How It Works.....................................................................................1
AdSpeed Configuration.....................................................................2
Optional Speed Switch......................................................................2
Installation........................................................................................3
Opening an Amiga 500..................................................................3
Opening an Amiga 1000................................................................3
Opening an Amiga 2000................................................................5
InstallingAdSpeed.........................................................................5
TheAdSpeed Program.......................................................................6
Programming Information................................................................7
Compatibility....................................................................................8
OtherAmiga Products from ICD.......................................................8
AdRAM 540..................................................................................8
AdRAM 560D...............................................................................9
AdRAM 2080................................................................................9
AdSCSI 2000.................................................................................9
AdSCSI 2080...............................................................................10
AdIDE....................................................................................10
Flicker Free Video........................................................................11
Warranty

1
Introduction
AdSpeed is a 68000 accelerator for all 68000-based Amiga computers (500,
1000, and 2000). It runs at 14.3 megahertz (MHz), twice as fast as the 7.16
MHz CPU a standard Amiga uses. It won’t double the speed of everything
your computer does, for reasons described below, but it will produce a
noticeable improvement in performance for almost all of your programs.
Because of the nature of the Amiga’s operation, some programs will show
much more improvement than others.
How It Works
The Amiga is designed with two address and data busses. Both of these are
designed to operate at 7.16 MHz, not faster.
The custom chip bus is shared by the 68000 central processing unit (CPU) and
the custom chips used by the computer for graphics, sounds, and other
features. When the custom chips have access to the bus, they can directly
manipulate the data stored in chip RAM, the random access memory located
on this bus.
Since DMA on the custom chip bus is invisible to the CPU (and AdSpeed),
chip RAM is not cached by AdSpeed. This has little effect on the performance
of AdSpeed, since program code in all but the strangest programs will always
load into FAST RAM first.
The expansion bus is restrained to 7.13MHz to allow compatibility with
existing expansion devices. FAST RAM, hard drive interfaces, and other
devices use this bus.
DMA on the expansion bus (usually hard drive interfaces) is visible to
AdSpeed. When it occurs, only the addresses accessed are invalidated in the
cache.
Even with the 68000 running at 14.3 MHz, it must emulate an 7.16 MHz bus
cycle when accessing the RAM to remain compatible with the rest of the
system. With nothing other than a high speed 68000, little performance
increase will be realized.
AdSpeed uses a high speed static RAM cache and cache tags to gain its speed
increases. When an address is needed by the CPU, the cache tags are checked
to see if that information is already in the cache. If it is not, the data is read
normally from the computer’s RAM, and no speed increase is realized. It is
also stored in the cache. If the information is already in the cache, the CPU

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can use it without having to access the computer’s RAM. This allows for a
full 14.3 MHz bus cycle. Information is kept in the cache until the space is
needed for newer information.
This RAM cache is most effective with loops in programs, since the whole
loop can be stored. Programs using many such loops can run almost twice
as fast as usual.
AdSpeed Configuration
AdSpeed has two jumpers that configure aspects of its operation. These are
the pairs of pins A & B and at the end of the board. To change the settings
of these jumpers, move the supplied jumper plug so that it covers both posts.
A & B determine the starting speed. If they are not connected, AdSpeed will
begin in 14.3 MHz high speed mode. This is the way AdSpeed is set when
shipped. If A & B are connected, AdSpeed will begin in true 7.16 MHz mode.
A & B should be connected if you wish the computer to boot in 100%
compatible 7.16 MHz mode. This is useful for copy protected games that
don’t work properly when accelerated. This does not permanently disable
AdSpeed. You may switch it back to high speed mode through software.
You may optionally install a switch to the A & B jumper to control speed
switching. This is described later in the Optional Speed Switch section.
Jumper pair C & D are for future options. These should be left open.
Optional Speed Switch
You may, if you wish, install a hardware switch to AdSpeed A & B pads. This
switch will perform two different but related functions.
The first function of the switch is to determine the starting speed. If the
switch is open, AdSpeed will boot in 14.3 MHz mode. If it is closed, AdSpeed
will boot in 7.16 MHz mode. You may change from the default speed with
either the switch’s second function or the software.
The second function of the switch is to change speed while the computer is
running. If the switch is opened, the speed will change (if necessary) to 14.3
MHz. If the switch is closed, then the speed will change (if necessary) to 7.16
MHz.
Note that the position of the switch does not necessarily reflect the operating
speed of AdSpeed, since the speed may be changed through software. For

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example, if the switch is in the 14.3 MHz position and you use the program
AdSpeed to change the speed to 7.16 MHz, you will have to move the switch
to the 7.16 MHz position and back to the 14.3 MHz position to change the
speed to 14.3 MHz.
To install this option, locate a suitable single pole single throw switch and
mount it somewhere on the case. Connect the switch to the A & B pad pair
with 30 gauge wire. You can label the positions to help remember which is
which if you wish.
Installation
Installation of AdSpeed is simple. The hardest part is opening your com-
puter.
Opening an Amiga 500
Disconnect your keyboard, monitor, mouse, power cord, and anything else
connected to your computer. You will need a T-10Torx®screwdriver. Turn
your computer upside down. Remove the three screws along the front edge
of your computer and the three along the rear edge. Turn the computer back
up and lift the cover off. Note that you may have to move the cover slightly
to the right to get it over the floppy drive eject button.
Note the orientation of the cable going from the keyboard to the main board
of your computer. Either record the colors or mark the connector so that you
will be able to replace it correctly. Unplug this cable and the ground strap
that connects the keyboard to the shield around the floppy drive. Then lift
the keyboard slightly backward and off.
Remove the four Torx screws holding the upper shielding in place. These are
around the front left side.
Bend up four tabs holding the shielding in place. Three are near the floppy
diskette drive and one is at the back left corner. Lift the shielding off.
Opening an Amiga 1000
Disconnect your keyboard, monitor, mouse, power cord, and anything else
connected to your computer. Open the panel on the front, loosen the screws
holding the 512K RAM expansion, and remove it.
Turn your computer upside down. Remove the five screws sunken in holes
on the bottom holding the case together. Turn the computer right side up

4
Figure 1
Figure 2
Figure 3

5
and remove the top. If this is the first time you have had your computer open,
be sure to admire the signatures inside the top of the case. Loosely put the
screws into the holes in the top so that you don’t lose them.
Remove the main shielding. It is held in place by fourteen screws and two
twisted tabs.
Carefully remove the front panel. The power LED will pull from the cover.
The drive LED will unplug.
Disconnect the floppy diskette drive housing. It is held in place by four
screws and four spacers. The spacers may be loosed and removed with a
flat-bladed screwdriver.
Disconnect the floppy diskette drive from its mounting frame, be careful not
to subject the drive to sudden jolts that could cause alignment problems.
You will need to cut a notch in this floppy drive mounting frame as shown
in figure 1 to prevent it from shorting to AdSpeed. You can do this with tin
snips, a hack saw, or a file.
Reconnect the floppy diskette drive to its mounting frame. It will be easier
to install AdSpeed if you wait until later to reconnect the frame to the
computer.
Opening an Amiga 2000
Disconnect your keyboard, monitor, mouse, power cord, and anything else
connected to your computer. Remove the four screws at the bottom of the
sides of your computer and the screw in the top middle of the back as shown
in figure 1. Make sure you remove the correct screw from the rear of your
computer.
Pull forward and lift off the top cover of your computer.
The power supply/disk drive subassembly is held into place by seven
screws. Locale and remove the four screws on the rear of the computer
shown in figure 2. Then locate and remove the three screws on the front on
the computer that hold this subassembly in place. Two of them are below
the large (5¼”) drive bay. The other one is just to the left of the large drive
bay.
Installing AdSpeed
Locate the 68000 chip in your computer. It has 64 pins and will be the largest
integrated circuit in the computer. In the 500, it is on the left side of the

6
computer next to the expansion port. In the 1000, it is directly behind the
floppy disk drive. In the 2000, it is near the front, just to the left of the drive
bays. Note on which end the notch on the chip is located.
With a small screwdriver or IC extraction tool, remove the 68000 from the
computer. If using a screwdriver, pry gently under alternate ends until the
chip is free. Set the CPU chip aside aside.
Plug AdSpeed into this socket so that the notch on the large chip on AdSpeed
points in the same direction the old CPU chip did. Make sure all the pins line
up with the holes. Push AdSpeed into place. That’s it!
Reassemble your computer.
TheAdSpeed Program
The program AdSpeed allows you change the operating mode of your
AdSpeed at any time. It also displays the current operating speed.
To run the program AdSpeed, just double-click on its icon or type its name
in a CLI. You may also add it to your startup-sequence. AdSpeed detaches
itself from the CLI, so you don’t need to use the run command.
When run from the CLI, the program AdSpeed can be used.
Once run, AdSpeed opens a small window on the Workbench screen, so
small that only the title bar and close, front, and back gadgets are visible. The
title bar shows the current operating speed of the computer.
To use the program, click on the AdSpeed window to make it the active one.
Then press and hold the right mouse button to activate the menu bar. While
still holding the right button, move the mouse pointer to the word “AdSpeed”
in the menu bar. A menu will drop down. Move the pointer to either the “14
MHz” or “7 MHz” selection and release the mouse button. The computer will
switch to that operating speed.
To quit the program, click on the close gadget of the window.

7
ProgrammingInformation
The following C program demonstrates how to detect the presence of Ad-
Speed and switch it on and off:
/*
Sample code of Manx C compiler
*/
#include <ctype.h>
#include <stdio.h>
AdSpeedOn() {
/* Turn AdSpeed on */
#asm
move #0,$b00000
#endasm
}
AdSpeedOff() { /* Turn AdSpeed off */
#asm
move #0,$b10000
#endasm
}
long TearTime() { /* Determine current speed of CPU */
register int Result; /* D4 with Manx compiler */
Forbid(); /* Turn off task switching */
#asm
movem.l d0/d1,-(sp)
clr.l d4 ;Result
move $dff004,d0 ;initial vertical scan position
WaitLoop:
move $dff004,d1 ;Wait until vertical position changes
cmp d0,d1
beq WaitLoop
WaitLoop2:
addq.l #1,d4 ;Start counting
move $dff004,d0 ;Wait for another change in vertical position
cmp d0,d1
beq WaitLoop2

8
movem.l (sp)+,d0/d1
#endasm
Permit () /* Turn task switching back on */
return(Result)
}
main() {
int Speed;
if (TestTime() > 0x12) Speed = 1; /* save current AdSpeed status */
else Speed = 0;
AdSpeedOff();
If (TestTime() > 0x10) printf(“No AdSpeed\n”);
else {
AdSpeedOn();
if (TestTime() < 0x12) printf(“No AdSpeed\n”);
else {
if (!Speed) AdSpeedOff(); /* Restore original AdSpeed Status */
printf(“AdSpeed present\n”) ;
}
}
exit(0);
}
Compatibility
There are very few programs with which AdSpeed will not be compatible in
high speed mode. Programs that depend heavily on the time it will take to
execute instructions will not work well. Some programs, especially games,
may run too fast. Others, such as pseudo graphics mode viewing programs,
may produce a garbled display. In general, any program that assumes that
instruction execution will take a specific amount of time will not work as
expected.
Programs that test for the existence of RAM by writing to an address and
then reading it will also not work properly when AdSpeed is turned on.
When the address is written, the value is also written to the cache. When the
address is subsequently read, the information is read from the cache. It is
usually sufficient to turn off AdSpeed before the program is run, then back
on (through hardware or software) after the RAM test is complete. ICD’s