Posts tagged EPROM
Upgrading your DDI-1 to PARADOS is quite straight forward. You will need :-
- Amstrad DDI-1 disk interface
- Philips screwdriver
- 27(C)128 EPROM containing PARADOS
- Open the DDI-1 by removing the 2 screws.
- Carefully remove the AMSDOS ROM chip
- Insert the PARADOS EPROM
- Re-assemble the DDI-1 box
Over the weekend, I upgraded one of my spare Amstrad CPC464 machines to the same specification as the CPC6128. I have been wanting to do this for years! There are 3 things you need to do to upgrade your CPC464.
1. Replace the OS and BASIC ROM. I took the OS and BASIC ROM files from the WinAPE emulator ROM folder. There is only 1 ROM chip in the 464, so you have to merge the OS and BASIC rom files together. I used the following MS-DOS command to merge the files. You can use the cat command in linux to merge files too.
copy /b OS.ROM+BASIC.ROM 6128.ROM
Once you have the ROM file, burn this to a 27(C)256 EPROM. I removed the original ROM chip, put in a IC socket and them popped in the EPROM.
2. Add and additional 64k RAM. I had a dk’tronics 64K RAM pack. If you are luckly enough to have a RAM pack that has the removable RAM chips, you can upgrade it to 256K.
3. Add a disk drive. Either a 3″ or 3.5″ drive via a DDI-1 disk interface.
Thats it – my CPC464 now works like a CPC6128. It even has the same startup information page. It will say 128k even if you dont have the RAM pack attached. The 128k text is hard coded into the OS ROM.
Making a custom Amstrad 464 and 6128 plus & GX4000 cartridge is quite simple – but it does mean sacrificing an existing cartridge. The main reason for this is you need the ACID protection chip. You can read more about the ACID chip on the CPC Wiki.
I sacrificed my SwitchBlade cartridge – but I successfully removed the EPROM so I can still use it in my ‘Multicart’.
So, all I had to do was removed the old EPROM and fit a IC socket.
Once the cartridge was ready, I needed to burn some software onto a blank 27C1001 EPROM. The CPR files you find on emulation websites etc will not work. You need to convert them to .BIN binary files. There is a great tool here that does that very job. So, once you have the .BIN file, write it to the EPROM using your EPROM programmer and you are good to go.
You will need :
- 8 x 32k SRAM Chip (I used a UMC UM62256A I removed from a BBC Model B SRAM mod)
- 28 pin DIL socket (You dont need this, but its a good idea)
- 27C256 EPROM or equivalent EEPROM
- Action Replay 6.0 ROM image (Available here.)
- Soldering iron, solder etc
- EPROM programmer
- Program your EPROM/EEPROM with version 6 of the Action Replay software.
- Dismantle the Action Replay. Mine was held together with 1 screw.
- Take the PCB out of the case.
- Carefully remove the large PROM at the bottom of the PCB near the edge connector.
- Solder in the 28 pin DIL socket.
- On the underside of the PCB, under where you just installed the DIL socket, you will see 3 solder pads. Join the 2 pads that are closed to the 2 buttons at the top. Photo here.
- Insert the SRAM chip in the new socket.
- Insert the EPROM you just programmed into the ROM socket.
Once you have finished, your board should look like this.
SymbOS is a GUI operating system available for the Amstrad CPC, PCW and the MSX range of computers. There are 2 ways to run SymbOS on the CPC : Floppy disk or ROM. I decided to go down the ROM route.
If you want to use EPROMS, you need the following hardware.
- ROM board/box
- 4 * 27(C)128 EPROMS
When you turn the CPC on, you get the following screen.
Ive finally finished this small project. Ive made a EPROM with the AMSDOS replacement called Parados. Ive simply burnt the ROM file onto a 27128 EPROM. Ive then remvoed the AMSDOS ROM(40015) from the 6128, installed a socket and droped in the Parados ROM.
The next part of the project is to get a 27C256 EPROM. This would then allow me to have both AMSDOS and Parados on the same EPROM. I attach a switch to the EPROM to allow me to choose which OS is selected when the machine is turned on.