This has been copied from my old website from circa 2021.
CD32 Motherboard
Information on the CD32 main board
Some information comes from the CD32 service manual..
The system consists of a 4 layer PCB for the main board and 2 additional PCBs, one for the Audio/LEDs and one for the CD-ROM drive.
The motherboard for the Amiga CD32 is roughly 6″ by 12″ and is a four layer board. On the main PCB – is a 14MHz 68EC020, the AA chipset, an ASIC called Akiko, a DAC for playing standard CD audio, and a small amount of EEPROM.
Akiko is a 160-pin PQFP surface-mounted device containing most of the remainder of the logic necessary m the Amiga CD32. It includes the CD-ROM control logic and the system timers. The EEPROM is 8K bits, and designed for storing Settings, high scores, bookmarks, etc., on the Amiga CD32.
In addition to the AA chips, Akiko, the CPU and the EEPROM/ the main board contains 2MB of DRAM as Chip RAM. A PAL or NTSC modulator is also included on the main board.
The Compact Disc DAC is a standard 18-bit, 8x oversampling DAC. Along with the superb audio quality of the DAC, the Amiga CD32 expansion connector has digital audio input capability in order to mix an external source such as MPEG audio with the CD audio and Amiga audio.
There were two released version of the PCB, version 3 was the standard PCB for PAL/NTSC machines. A special version 4 PCB was made for the French market (they use a SECAM TV system) The only difference between the two types is the video encoder.
It is reported that the On/Off switch is from the old C64 production line and is liable to cause problems, see the CD32 PSU Information page for more information.
CD32 Memory Map
This information comes from the CD32 service manual.
CD32 CDROM drive information
CD32 CD-ROM Subsystem
Here is some information on the internal drive of the CD32.
This information comes from the CD32 service manual.
A separate PCB (2 layer) contains the CD electronics. This board contains the RF amp and servo chip, the audio DSP chip, and a small microcontroller for controlling the servo, focus, and communicating with the main CPU. The main CPU and RAM perform any prefetching/ buffering and ECC as necessary.
The mechanism for the Amiga CD32 is a Sony KSM-2101BAM. The KSM-2101BAM has no drawer, or drawer motor. It is simply a spindle motor, traverse motor, and optical pickup. Chinon will provide the drive PCB. The electronics are based on the Sony CD chipset, which support double-speed operation. The microcontroller firmware has changed slightly in this version of the drive to (1) remove the firmware to control the drawer, and (2) revise the communications protocol to use a new 3-wire channel instead of the older 6-wire channel (to save pins on the ASIC) and (3) support multi-session discs (which is useful for PhotoCD support).
The software driver for the CD subsystem has been converted to run entirely on the 68EC020. The software also supports Akiko and its new DMA. This driver incorporates all the prefetching tricks and double-speed support completely from the 68EC020. It also supports both Mode 1 and Mode 2 (Form 1 and 2) discs. This is required to read all types of CD media called out in the Philips Yellow Book. This includes CD-I discs, PhotoCD® discs, and MPEG discs.
CD32 PSU replacement
This is left here for reference, it was written before I’d designed the ATX PSU adaptors I sold until 2023.
PC Power Supplies as replacements/upgrades
It is quite common now to replace the under rated original Amiga PSU with a PC one, asPC PSUs start at 135W and go to over 500W it is easy to see why.
There are minor differences in using an AT or ATX PSU to power an Amiga and leter on I will explain the witing.
AT PSU
Not really used in PCs since 1998/99 due to the PC requirement that software can switch
the PC off (or a Microsoft plan to stop their software crashing).
Normally found in old/dead PCs (they have some uses). To hook it upto your Amiga you will need to note wiring of the square DIN plug (check the underside of the PSU) and then cut it off.
Commodore never seemed to use the same colour code in all Amiga models so you will need to check your wiring with a multimeter. See the power connector section for more details.
Once you have wired up the Amiga cable, connect a 21W car bulb across the +5V (RED) and 0V (BLACK) wires. This will provide a suitable load to turn on the PSU and you can then ensure you have the right voltages going to the right pins before pluging into your Amiga.
If all seems well, connect to your Amiga and switch on!
Important note. Modern PSUs have what is called crow bar protection, if you short it out or wire up backward, to cause a large power surge, it will switch off. Don’t count on this, double check your wiring!
Some AT PSUs had the mains switch inside the PSU housing, that is fine. Some had a mains lead that went to the power switch on the front of the PC case. If possible avoid this type unless your Amiga case has a suitable power switch.
Final note, do not open a PSU case. Due to their operation, a typical computer power supply can have upto 400V DC stored within for a considerable time after power off. If you inadvertantly touched the wrong part you could be killed!
ATX PSU
This is the type of PSU found on all modern PCs and within cases. There are 2 important differences to the AT PSU. The following conditions must be met.
1) You need to have about a 1.0 Amp load on the 5V supply for it to work.
2) You need to connect the PS-ON line to ground for the PSU to switch on.
Condition 1 is easily satisfied, an Amiga uses enough current on the 5V supply.
Condition 2 is a bit trickier.
It is possible to create a simple circuit to use the push to make power button of
an ATX case. A simpler solution is to bare back the insulation of the PS-ON wire
(normally green) and of a ground wire (black). Then either twist them together or
add a link wire, solder it an insulate it. Now when you use the mains switch on
the back of the ATX PSU, it will switch on the PSU.
the circuit to utilise the PC front panel switch is available here
CD32 Expansion port
Update & Notes
The original notes on the CD32 expansion port were released in 1995, they left out a few pins, which I have added to the list below. there is built in support (I think) for a 68030 processor on this expansion connector, previously these signals were marked as no connect (n/c).
The mating connector is a 182 way MCA connector which is possible to obtain.
#####################################################################
## CD32 Expansion port info. 1994-07-05 by Anders Stenkvist ##
## Updated 19th April 2002 by Ian Stedman ##
#####################################################################
2 84___86 182
|--- TOP
//////////////////////////// //////////////////////////// v
/==========================/ /==========================/
^ ^ ^ ^ ^
1 83 85 181 |___ BOT
Note DGND = digital GND
VCC = +5V
A * after a signal denotes active low.
Pin # Name Comment
===========================================================================
Pin 1 A31 Probably not connected since 68EC020
| | |
Pin 8 A24 Probably not connected since 68EC020
Pin 9 DGND
Pin 10 VCC
Pin 11 A23 Address bus
| | |
Pin 18 A16 |
Pin 19 DGND
Pin 20 VCC
Pin 21 A15 |
| | |
Pin 28 A8 |
Pin 29 DGND
Pin 30 VCC
Pin 31 A7 |
| | |
Pin 38 A0 Address bus
Pin 39 DGND
Pin 40 VCC
Pin 41 D31 Data bus
| | |
Pin 48 D24 |
Pin 49 DGND
Pin 50 VCC
Pin 51 D23 |
| | |
Pin 58 D16 |
Pin 59 DGND
Pin 60 VCC
Pin 61 D15 |
| | |
Pin 68 D8 |
Pin 69 DGND
Pin 70 VCC
Pin 71 D7 |
| | |
Pin 78 D0 Data bus
Pin 79 DGND
Pin 80 VCC
Pin 81 IPL2* Interrupt Priority Level 2 (68020 signal)
Pin 82 IPL1* |
Pin 83 IPL0* Interrupt Priority Level 0
Pin 84 IPEND Interrupt pending
Pin 85 RST Request to send (RS232 port)
Pin 86 HALT* Processor Halt
Pin 87 ECS* Not implemented on 68EC020 (68030 signal)
Pin 88 OCS* Not implemented on 68EC020 (68030 signal)
Pin 89 SIZE1 Indicates number of bytes remaining to transfer
Pin 90 SIZE0 Indicates number of bytes remaining to transfer
Pin 91 AS* Adress strobe
Pin 92 DS* Data strobe
Pin 93 R/W* Read/Write
Pin 94 BERR* Bus Error
Pin 95 STERM* 68030 STERM (reserved)
Pin 96 AVEC* Autovector request during interrupt acknowledge
Pin 97 DSACK1* Data transfer and size acknowledge
Pin 98 DSACK0* Data transfer and size acknowledge
Pin 99 CPUCLK_A CPU Clock 14 MHz
Pin100 E Peripheral Enable Clock
Pin101 DGND
Pin102 VCC
Pin103 FC2 Function codes
Pin104 FC1 Function codes
Pin105 FC0 Function codes
Pin106 RMC* Read Modify cycle
Pin107 CIIN* 68030 CIIN (Reserved)
Pin108 CIOUT* 68030 CIOUT (Reserved)
Pin109 CBREQ* 68030 CBREQ (reserved)
Pin110 CBACK* 68030 CBACK (Reserved)
Pin111 CPU_BR* CPU bus request
Pin112 EXP_BG* Expansion bus grant
Pin113 CPU_BG* CPU bus grant
Pin114 EXP_BR* Expansion bus request
Pin115 CPU_BGACK* CPU bus grant Acknowledge
Pin116 EXP_BGACK* Expansion bus acknowledge
Pin117 PUNT* Back off signal to console
Pin118 RESET* General RESET
Pin119 INT2* Generate a level 2 interrupt
Pin120 INT6* Generate a level 6 interrupt
Pin121 KB_CLOCK* Keybord clock
Pin122 KB_DATA* Keybord data
Pin123 FIRE0* Fire buttons
Pin124 FIRE1* |
Pin125 LED* Power On Led
Pin126 ACTIVE* CD Drive active led
Pin127 RXD* Serial data in
Pin128 TXD* Serial data out
Pin129 DKRD* Disk Read Data
Pin130 DKWD* Disk Write Data
Pin131 SYSTEM (Reserved)
Pin132 DKWE* Disk Write Enable
Pin133 CONFIG_OUT* Zorro config signal
Pin134 CONFIG_IN* Zorro config signal
Pin135 DGND
Pin136 +12V
Pin137 DGND
Pin138 +12
Pin139 17MHZ CD-Drive/CD-DAC clock
Pin140 EXT_AUDIO* External audio enable
Pin141 DA_DATA CD-Data
Pin142 MUTE* Audio mute signal
Pin143 DA_LRCLK CD-Data Left Right clock
Pin144 DA_BCLK CD-Data bit clock
Pin145 DGND
Pin146 VCC
Pin147 DR Digital Red
Pin148 DG Digital Green
Pin149 DB Digital Blue
Pin150 DI Digital Intensity
Pin151 PIXELSW_EXT* External genlock pixel switch (Video)
Pin152 PIXELSW* Genlock Pixel Switch (Video)
Pin153 BLANK* Video blanking signal
Pin154 PIXELCLK Pixelclock for manipulating RBG data
Pin155 DGND
Pin156 VCC
Pin157 CSYNC* Composite sync
Pin158 CCK_B Color clock ?????
Pin159 HSYNC* Horizontal sync
Pin160 VSYNC* Vertical sync
Pin161 VGND Video ground
Pin162 VGND Video ground
Pin163 AR_EXT External Analog Red
Pin164 AR Analog Red
Pin165 AG_EXT External Analog Green
Pin166 AG Analog Green
Pin167 AB_EXT External Analog Blue
Pin168 AB Analog Blue
Pin169 VGND Video ground
Pin170 VGND Video ground
Pin171 NTSC* NTSC
Pin172 XCLKEN* Enable External video clock (Genlock)
Pin173 XCLK External video clock (Genlock)
Pin174 EXT_VIDEO* Disable internal video interfaces
Pin175 DGND
Pin176 VCC
Pin177 AGND
Pin178 +12
Pin179 LEFT_EXT External Left sound
Pin180 LEFT Left sound
Pin181 RIGHT_EXT External Right sound
Pin182 RIGHT Right sound
NOTE: Signals with a _EXT suffix are intended for the CD32 FMV module.