Commodore Amiga A500 Product manual

Technical Reference Manual
0 Commodore

Commodore"Amiga"
AS00/AZ000
Technical Reference
Manual

COPYRIGHT
This manualiscopyright
0 1986. 1987 byCommodore-Amiga.Inc.All RightsReserved. Thisdocument
may not. in whole or part. be copied, photocopied, reproduced, translated or transferred to any
electronic medium or machine readable form without prior consent, in writing, from Commodore-
Amiga. Inc.
Amiga is a registeredtrademark ofCommodore-Amiga. Inc.
Commodore and CBM are registered trademarks ofCommodore Electronics Limited.
Hayes isa registeredtrademark of Hayes Microcomputer Products. Inc.
IBMisa registeredtrademark of International BusinessMachinesCorporation.
Maclntosh isa trademark ofApple Computer. Inc.
DISCLAIMER
THE INFORMATIONIS PROVIDED"AS IS" WITHOUT WARRANTY OF ANY KIND. EITHER EXPRESSEDOR
IMPLIED. THE ENTIRE RISK AS
TO THE ACCURACY OF THE INFORMATION HEREIN IS ASSUMED BY
YOU. COMMODORE-AMIGA DOES NOT WARRANT. GUARANTEE. OR MAKE ANY REPRESENTATIONS
REGARDING THE USE OF, OR THE RESULTS OF THE USE OF, THE INFORMATION IN TERMS OF
CORRECTNESS. ACCURACY. RELIABILITY, CURRENTNESS. OR OTHERWISE. IN NO EVENT WILL
COMMODORE-AMIGA. INC. BE LIABLE FOR DIRECT. INDIRECT, INCIDENTAL OR CONSEQUENTIAL
DAMAGES RESULTING FROM ANY DEFECT INTHE INFORMATION EVEN IF IT
HAS BEENADVISED OF
THE WSSlBlLlTY OF SUCH DAMAGES. SOME LAWSDO NOT ALLOW THE EXCLUSION OR LIMITATIONOF
IMPLIED WARRANTIES OR LIABILITIES FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES. SO THE
ABOVE LIMITATIONOR EXCLUSION MAY NOT APPLY.
Schematicsrepresent current machinewhich is subjecttochange without notice.
Credits
The material for this manual was produced by Engineering, Documentation,
and Technical Support staff at Commodore West Chester. Commodore
Braunschweig, and Commodore-Amiga. Individuals contributing major por-
tions of information and input are Dave Haynie, Jeff Porter, Phil Lindsay,
Carolyn Scheppner, Lisa Siracusa, George Robbins, Andy Finkel, Eric Cotton,
Jeff Boyer. Steve Ahlbom, Steve Beats, Dieter Preiss, Bernd Assmann, and
Torsten Burgdorf.
This manual was compiled and edited by Steve Finkel.
Manual design by Jo-Ellen Temple and Wilson Harp.

AZOOO/AS00 Technical Reference Manual
Table
of Contents
Section 1 Summary of Differences
Section 2 System Block Diagrams
Section 3 Amiga Expansion
3.1
Designing hardware for the Amiga Expansion Architecture
3.2 Driver Documentation
3.3 Software for Amiga Expansion
3.4 Amiga Expansion Connectors
100Pin
86 Pin
Video Slot
Section 4 PC Bridgeboard
4.1
Description of the PCIXT emulator for the Amiga 2000
4.2 BlOS entry points
4.3 Janus library
Section S Amiga Hard DisWSCSl Controller
Section6 Custom Chips
Fat Agnus Chip
8520Chip
Section 7 Miscellaneous Hardware Information
7.1 ClocWcalendar registers
7.2 Power budgets
7.3 A2000 PAL equations
7.4 B2000 Jumpers
Appendix A. Diagrams
A-l
Backplane Example
A-2 PIC Example
A-3 A500 Exterior (86-pin expansion connector)
A-4 Amiga 2000 Expansion Board Layout
A-S Amiga 2000 Form Factor
A-6 Amiga 2000Video Card
A-7 86-Pin Slot Expansion Board
A-8 A2000lB2000 Keyboard Connector Pinout
A-9 Amiga 50012000 Mouse Diagram and Pinout
Appendix B. Schematics
A2000 Schematics
B2000 Schematics
A500 Schematics

Section 1
Summary of Differences
This manual presents technical documentation for three different
Amiga models, comparing them tothe original Amiga, referred toas
model A1 000. Technical information included in this manual
is rel-
evant for the following Commodore Amiga models:
the Amiga 500 (A500), a low-cost version of the origi-
nal Amiga computer, software-compatible with the
A1 000. Unlike the A1
000, the A500 has an integrated
keyboard, provision for internal memory expansion up
to 1 megabyte, new-style hardware connectors, and
Kickstart code in
ROM.
Two versions of the Amiga 2000:
theA2000 is software-compatiblewith theA1 000 and
has internal slots, real time clocWcalendarand new-
style hardware connectors.
the B2000,the cost-reduced version of the Amiga
2000,features some different custom chips, but is
otherwise similar tothe A2000.
The B2000 is still under development, and the information present-
ed in this document is subject tochange. The information included on
the B2000 is intended to aid developers in designing software and
peripherals that are applicable for both the current and upcoming
version of the Amiga 2000.
Unless differences are specifically noted, information presented for
the A2000 also holds true for the B2000. The differences between
the two Amiga 2000 models are mainly hardware differences which
will affect peripheral design, but not the way the computersfunction
with software. Section 2 contains system block diagrams for all
three new Amiga models.
KICKSTART IN ROM
Both the Amiga 2000and the Amiga 500feature version 1.2 of
lckstart built into ROM. Kickstart 1.2 (currently version 33.180)
boots automaticallywhen the Amiga is turned on.

EXTRA KEYS ON THE
Both the Amiga 2000and 500 feature 94-key keyboards, as com-
KEYBOARD
pared to the A1 000's 89-key keyboard. (The European versions of
thekeyboards have
96 keys.) The new keys areall located on the nu-
meric keypad, and include:
KEY
SCAN CODE
Left parentheses
( $5A
Right parentheses 1 $5B
Slash
I $5C
Asterisk
* $5D
Plus
+ $5E
In PC mode on the Amiga 2000 (using a Bridgeboard), these keys
assume typical PC functions, including Number lock (left parenthe-
sis), Print screen (asterisk) and Scroll lock (right parenthesis).
On some keyboards, the left Amiga key has been replaced by the
Commodore key. This key performs identically in either case.
RAW KEY CODES ON
Keyboard Layout Showing Raw Key Codes
THEKEYBOARD
Figure 1 .l Key Codes
Note: On the U.S. keyboard, the keys with codes 44 and 60 are
extended toinclude the European keys with codes 2Band
30.
respectively. Also note that England uses the U.S. rather than
the European keyboard, but not the U.S. keymap.
See Table 1 - 1 atthe end of this section for a table of the raw key
codes.

EXTERNAL SYSTEM v0
This section describes each I10 interface in detail, and some of the
tradeoffs made with respect to
AI 000compatibility.
The Amiga 2000and Amiga
500 have differences in the serial and
parallel ports from the Amiga 1000,the main difference being
changes in the sex of each port (changingthe serial tofemale and the
parallel to male),which allowsthe new Amigas to use standard inter-
face cables.
RS232 and MIDI Port
The RS232 connector on the A500 and A2000 is form fit and func-
tion identical toa Commodore PC-10120with a fewexceptions.
This
is the OPPOSITE sex connector from the A1000. The connector
is a shielded male DB25P connector. The A1 000supplies various
non-standard RS232 signals on the DB25 connector. These non-
standard signals were removed wherever possible. The RS232 con-
nectar is NOT physically compatible with some MIDI interfaces but is
compatible with the ~miga~odem/1200RS (model 1680).Below is
a comparison chart between the RS232 standard,a Hayes Smart-
modem standard, the A1 000 RS232, and the new Amiga 50012000
RS232 connector.
AS001
PIN RS232 A1000 A2000 PC10 HAYES@ DESCRIPTION
GND
TxD
RxD
RTS
CTS
DSR
GND
DCD
-
-
S.SD
S.CTS
S.T X D
TxC
S.R X D
RxC
-
S.RTS
DTR
SQD
R I
SS
TxCl
-
Frame ground
Transmit Data
Receive Data
Request to send
Clear to send
Data set ready
Signal ground
Carrier detect
+ 12volt power
- 12volt power
Audio output
Speed Indicate
GND
TxD
RxD
RTS
CTS
DS
R
GND
DCD
GND
TxD
RxD
RTS
CTS
DSR
GND
DCD
+ 12v
- 12v
AUDO
-
CND
TxD
RxD
RTS
CTS
DSR
CND
DCD
+ 12v
- 12v
GND
TxD
RxD
-
CTS
DSR
GND
DCD
-
- 5Vdc
AUDO
AUDl
EB
INTZ*
- 5 volt power
Audio output
Audio input
Port clock 71
6KHz
Interrupt IineJAudio input
AUDl
DTR
+ 5Vdc DTR DTR
-
DTR Data terminal ready
+ 5 volt power
Ring indicator
+ 12volt power
3.58MHz clock
Buffered system reset
C2*
RESB*

As you will notice, the A500 and 2000deletes clocks and interrupt
lines from the A1 000. The
+ l - 5Vdc and reset lines are also de-
leted. The
+ 1 - 12Vdc lines are identical to a PC10120.
The following signals (formerlyon the RS232 connector)can
be found
on other connedors:
ResB = parallel connector
C2
= video connector
Centronics Port
The Centronics port also has some non-standard signals. Below is a
table comparing the A1
000 Centronics port with the A500lA2000
Centronics port. Again,this is the opposite sex from the A1 000
and the same sex connector as an IBMB-PC (i.e.,a female DB25
connector).
PIN A1 000 ASOO/AZOOO PC1 0
Video Output
DRDY*
Data 0
Data 1
Data 2
Data
3
Data 4
Data 5
Data 6
Data 7
ACK*
BUSY (data)
POUT(clk)
SEL
CND
CND
CND
CND
GND
+ 5v
NC
Reset*
STROBE*
Data
0
\ Data 1
j Data 2
Data
3
k; \
\ Data 7
ACK*
k. BUSY
h POUT
. SEL
%*A + 5v pullup
NC
RESET*
GND
GND
GND
GND
GND
STROBE*
Data
0
Data 1
Data 2
Data
3
Data 4
Data 5
Data 6
Data 7
ACK*
BUSY
POUT
SEL
AUTOFDXT*
ERROR*
INIT*
SLCT IN*
GND
GND
GND
GND
The A500 and A2000, like the A1 000, use a DB23 video connector.
This 23pin connector contains all the signals necessary toworkwith
a Genlock, but the current Genlock will need
to be redesigned in or-
der to meet the physical requirements of the
A500 and A2000, in-

stead of the A1 000. An A500 genlock will also have to supply its
own power. Power will not be provided for the Genlock. All signals
on the 23pin connector are the same except for the power.
In addition tothe 23pin video connector,the A500/B2000 provides
a monochrome composite video output,unlike the A1 000.This pro-
vides the capability of using a low-cost, high persistence mono-
chrome monitor with the
A500 for viewing 640 X 400 interlaced
video without as much flickering.
Power is provided for the A520 modulator and composite video
adapter.
Mouse and Joystick
The mouse andjoystick ports of the A500 and A2000 are identical
Ports
tothe A1 000, except that the current limiting protection circuitry
has been eliminated.The
A500 and A2000 use a different mouse
than the one the A1 000uses.
A diagram and information on this
mouse is included in Appendix
A of this manual.
Am mansionPort
The expansion port is electricallycompatiblewith theA1 000, but be-
cause of
its physical location, it cannot accept any A1 000expansion
peripherals without some further adapter. Power is supplied tothis
connector,but only enough for a ROM cartridge. The exact pinout of
this
86 pin edge connector appears later in this document, in thesec-
tion of Amiga expansion.The
A500 diagram in Appendix A showsthe
new positioning of this port (relative toA1
000) and the pin num-
bers.
AmRAM mansion
Associated with the built-in 512KB of RAM is a header socket to al-
low an additional 51
2KB of RAM and a battery backed-up real time
clock board to be added. This small PCB (theA501 RAM Expansion
Cartridge) can easily be installed by the user. The clock in this unit
functions the same asthat built into the A2000,which is reviewed in
Section 7-1.
AS00 Power Supply
The A500 power supply connector is similar tothat of the C128. The
Connector
pinout of the square 5 pin DIN connector is as follows:
PIN SIGNAL
1 + 5Vdc @ 4.3A
2 Shield Ground
3
+ 12Vdc @ 1.OA
4 Signal Ground
5 - 12Vdc @ .lA

External Disk Interface
The 23pin D-type connector with sockets (DB23S)atthe rear of the
COM~C~O~
Amiga is nominally used to interface to MFM devices.
The second disk drive port is similar to the A1 000,and is therefore
compatiblewith the 1010 or the 1020disk drive.The CPU will pow-
er one external 101
0 disk drive.
External Disk Connector Pin Assignment
Pin Name Dir Notes
RDY* I10 If motor on, indicates disk
installed and up to speed.
If motor not on, Identification
mode. See below.
DKRD* I MFM input data to Amiga.
CND
CND
CND
CND
GND
MTRXD*
13 SIDEB*
14 WPRO*
OC Motor on data, clocked into
drive's motor on flip flops by
the active transistion of
SELxB*.
Guaranteed setup time is 1.4
psec.
Guaranteed hold time is 1.4
psec.
9 SEL2B*/SEL3B*OC A500:Select drive 21A2000:
Select drive 3.
10 DRESB* OC Amiga system reset. Drives
should reset their motor on
flip flops and set their write
protect flip flops.
11. CHNG* 110 Note: Nominally used as an
open collector input. Drive's
change flop is setatpower-up
or when no disk is installed.
Flop is reset when drive is
selected and the head stepped,
but only
if a disk is installed.
270 ma maximum;410 ma
surge.
When below 3.75V,drives are
required to reset their motor
on flops, and set their write
protect on flops.
0
Side 1 if active, side 0 if
inactive.
I10 Asserted by selected,write
protected disk.

15 TKO* I10
16 DKWEB* OC
17 DKWDB* OC
18 STEPB* OC
19
DlRB OC
20 SEL3B*/ OC
Not Used
21 SE11BlSEL2B OC
22
INDEX* I10
Asserted by selected drive
when readlwrite head is
positioned over track
0.
Write gate (enable)to drive.
MFM output data from
Amiga.
Selected drive steps one
cylinder in the direction
indicated by DIRB.
Direction to step the head.
Inactive to step towards
center of disk (higher
numbered tracks).
A500: Select drive 3lA2000:
Not used.
A500: Select drive 1lA2000:
Select drive 2.
Index is pulse generated once
per disk revolution, between
the end and beginning of
cylinders. The 8520can be
programmed to conditionally
generate a level
6 interrupt to
the
68000 whenever the
INDEX* input goes active.
160ma maximum;540 ma
surge.
Note: * in signal name denotes active low signal.
External Disk Connector Identification Mode
An identification mode is provided for reading a 32bit serial identifi-
cation data stream from an external device. To initialize this mode,
the motor must be turned on then off. See pin
8, MTRXD* for a
discussion of how to turn the motor on and off. The transition from
motor on to motor off reinitializes the serial shift register.
After initialization, the SELxB* signal should be left in the inactive
state.
Now enter a loop where SELxB* is driven active, read serial input
data on RDY* (pin l),and drive SELxB* inactive. Repeat this loop a
total of
32 times to read in 32 bits of data.The most significantbit is
received first.

External Disk ConnectorDefined Identifications
$0000 0000 - no drive present
SFFFF FFFF - Amiga standard 3.25diskette
$5555
5555 - 48 TPI double density double sided
As with other peripheral ID'S, users should con-
tact Commodore Technical Supportfor
ID Assign-
ment.
The serial input data is active low and must there-
fore be inverted to be consistent with the above
table.
External Disk Connector Limitations
1. The total cable length including daisy chaining
must not exceed
1 meter.
2.
A maximum of 3 external devices may reside
on this interface (2for the A2000).
3. Each device must provide a 1000Ohm pullup
resistor on every open collector input.
Full BUSTermination
Unlike the A1 000 and the A500, both versions of the Amiga 2000
have an internal expansion bus, as a function of having an internal
card cage.
Internal RAM Expansion On the A500, memory at $C00000 is "slow" RAM (theprocessor is
onthe MOO
locked out by the custom chips) rather than fast RAM as suggested
by A1 000external expansion.Thus,when ExecBase is transferred to
$C00000 tofree up chip RAM, there is no speed advantage. Howev-
er,you would still be making real chip RAM availablefor other pur-
poses. The B2000 functions as the
A500 does in this regard.
EIA Ring Indicate
Support
The A500, A2000 and B2000 support the RS232 RI lead to allow
operation with modem standards.When the
RI signal is asserted,the
parallel port SEL line will be driven low.
If this function is not de-
sired,the
RI lead should be disconnected in the modem cable.

Time of Day Clock
Light Pen
In the A500, the Time of Day clock is tied tothe VSYNC signal rather
than the power line. This results in the theoretical error of several
minutes a day. For more precise timing, use the optional real-time
clock.
In genlock mode,the genlock peripheral provides a
30 Hz VIZ signal,
which results in the clock running half speed.
The light pen input on the
A500 and B2000 has been moved to the
second mouse port to allow use without a pass-thru mouse adapter.
On a
B2000, the light pen can bejumpered to port 0.
Monochrome
The A500 and B2000 provide a full-bandwidth 16-level qrev-scale
Composite Video
compositevideo output. Color composite is available withinbptional
A520 composite colorlrf video adapter.
Audio Filter C~t-out
The A500 and B2000 can cut outthe anti-aliasing filter by program-
matically turning off the "power on" LED. External bandwidth limit-
ing tobelow 15
KHz will be required for most applications. This per-
mits wider frequency response by using faster sampling rates.
AS00 Reset
The A500 implements a "hard-wired" Control/Commodore/Amiga
key reset rather than the "soft A1 000lA2000 keyboard reset.
"Shut down" keyboard messages are not transmitted.
A2000 Expansion Bus
The A2000 does not run the processor IPL lines beyond the 86 pin
IPL Lines
MMU connector. Instead, additional interrupt request lines are allo-
cated forfuture expansion devices. These lines are not supported by
the current software.

Table 1-1 RAW KEY CODES
Raw
Key Keycap
Number Legend
00
-
0 1 1 !
02 2 G
03 3 #
04 4 $
05 5%
06 6
-
07 7 &
08 8 *
09
0 A
9 (
0 B
0)
-
OC = +
0 D \ I
0 E
0 F 0
Unshifted
Default
Value
' (Accent grave)
1
2
3
4
5
6
7
8
9
0
- (Hyphen)
--
\
(undefined)
0
9
W
e
r
t
Y
U
i
0
P
l
(undefined)
1
2
3
a
S
d
f
9
h
j
k
I
' (single quote)
Shifted
Default
Value
- (tilde)
!
@
#
$
Oh
&
*
(
)
- (Underscore)
+
I
0 (Numeric pad)
Q
W
E
R
T
Y
U
I
0
P
{
}
l (Numeric pad)
2 (Numeric pad)
3 (Numeric pad)
A
S
D
F
G
H
J
K
L

Raw
Key Keycap
Number Legend
2 B
2C
2D 4
2 E 5
2 F 6
(Space bar)
BACK SPACE
TAB
ENTER
RETURN
ESC
DEL
Up Arrow
Down Arrow
Forward Arrow
Backward Arrow
Unshifted Shifted
Default Default
Value Value
(RESERVED) (RESERVED)
(undefined)
4 4 (Numeric pad)
5 5 (Numeric pad)
6 6 (Numeric pad)
(RESERVED)
z
X
C
v
b
n
m
, (comma)
. (period)
I
(undefined)
20
08
09
0 D
0 D
1 B
7F
(undefined)
(undefined)
(undefined)
(undefined)
<CSI>A
<CSI>B
<CSI>C
<CSI>D
(RESERVED)
z
X
C
v
B
N
M
<
>
?
. (Numeric pad)
7 (Numeric pad)
8 (Numeric pad)
9 (Numeric pad)
20
08
09
OD (Numeric pad)
0 D
1 B
7F
- (Numeric Pad)
l In shifted Forward Arrow and Backward Arrow, note blank space after <CSI>
<CS[> stands for Command Sequence Initiator.

Raw
Key
Number
50
5 1
52
53
54
55
56
57
58
59
5A
S B
5C
5 D
5 E
5F
Keycap
Legend
+
HELP
Unshifted
Default
Value
Shifted
Default
Value
<CS]> 10-
<CSI>11-
<CS]> 12-
<CS]> 13-
<CS1>14-
<CS]> 15-
<CS> 16-
<CS!> 17-
<CS!> 18-
<CSI> 19-
(
1
I
*
+
<CS!>?-

Section 2
System Block Diagrams
INTRODUCTION
This section featuressystem block diagramsforeach new Amiga, the
A2000, B2000 and A500, in that order.

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- RGB
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