Amiga 1200+
By Jeroen Vandezande
This project is a re-implementation of the Amiga 1200 board started from the schematics.
I made some changes and enhancements to the original schematics.
- All Original AA chips are needed and can be put into the sockets. These include Lisa, Paula, Alice, Gayle and the two CIA chips.
- Budgie being a TQFP package is soldered directly to the board.
- The keyboard controller has been replaced by a modern 8 bit MCU.
- Keyboard used to switch bootselector, set stereo separation and switch ROM banks.
- Because there are different Chip Ram configurations possible, the Chip Ram is moved to a separate board. (e.g. 1Mx4, 256Kx16 or 512Kx8 DRAM chips)
- Video output has been moved to a separate output board. This board get all Lisa output signals and also all the typical Zorro signals. This means that an RTG card can be developed.
- The PCMCIA slot has been removed and in the free space, a Compact Flash socket is located. This compact flash is connected to the IDE interface.
- The IDE interface is buffered using the otherwise unused Bus Buffer in Budgie.
- The power brick is replaced by an internal AC/DC power supply. This power supply is capable of:
- 5 Volts: main power rail 6 Amp capable
- 12 Volts: 1 Amp capable
- two PC standard 3 Pin fan headers are added to the board.
- An extra floppy power connector for powering ClockPort devices.
- An I2C controller has been added and there is a connector on board to connect I2C boards. (e.g. Real Time Clock modules)
- The I2C bus is also used to drive a DigiPot that is in the audio path, this is used to set the stereo separation of the Amiga Audio signals.
- Extension board connector for mouse/joystick/Network/Flash Floppy/Boot selector.
This project is Open Source: more on Bitbucket
I also post regular updates on Twitter: https://twitter.com/JeroenNumber42
Project history
Rev2
Here you can see Rev2 of the PCB with all the passives soldered.
Image:
Testing the clearance of the PSU under the keyboard.
Everything fits just fine under the keyboard and in the case.
Here you can see the build-in PSU more clearly. It is a 30W PSU, so it supplies up to 6A@5V.
Kickstart produces picture!
Video out in DiagRom
This is the backside of the A1200+
from left to right:
- Boot Selector
- Ethernet
- USB Mouse using SmallyMouse2
- Joystick 1
- Joystick 2
- External Disk drive
- Serial Port
- Parallel Port
- Audio
- Video Out
- On/Off switch
- Mains power inlet
All the PCBs together.
Rev1
Rev 1 PCB, hopefully, this one will give me some screen output...
Image:
May 2019
Booting Kickstart for the first time.
The colors are a bit off but still: HUGE step. Hooray!
A bug in the RGB bus is causing the colors to be off.
Image: Booting Kickstart
All the PCBs put together.
Image: Populated Rev1 board
Rev0
This is a rendering of the rev0 pcb
Image: a1200+ rendering
And some pictures of the real Rev0 pcb!
Image: a1200+ PCB
The Ram Board has arrived, soon will start populating that one...
Image: A1200plus ram board
Power-on reset of the keyboard controller and reset lines all over the board are working fine... I made sure that the reset was hold low for at least 450 ms.
Image: a1200 reset
Here is a picture of the connector on the bottom of the RamBoard and one on the main board... there will be 3 of those in a row
Image: a1200+ ramboard connector
Finished Test RamBoard ... and it fits on the mainboard!
Image: A1200+ finished ram board