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Multi Cartridge for Amstrad Plus

Dec 112010

Bryce finished another hardware project, this time for the Amstrad Plus series. It is a multi cartridge, which contains a 512 KB EPROM or Flash-ROM on which you can place 4 128 KB ROMs. You can use the DIP switches on the cartridge to select which of the four ROMs shall be used by the CPC. As always you can find more information about the cartridge and the board layout in the [[Multi Cartridge|Multi Cartridge]] article in the CPC Wiki. The project can be discussed here.

NOTE: You will still need a ACID protection chip in this cartridge.

MegaROM board

Amstrad CPC, Hardware 1 Response »

Oct 172010

Bryce released another great hardware project for the CPC. This time it is a ROM extension board which uses one big EPROM (1 MBit or 2 MBit) to store your ROMs instead of using small 16kb EPROMs, which are hard to find nowadays. With an 1 MBit EPROM you can use 8 16kb ROMs and with an 2 MBit you can use 16 16kb ROMs.
This is an DIY project, which means, that Bryce won’t build a batch of them, but you can get all files (schematics, board) and a description of it from the [[MegaROM]] article in the CPCWiki. You can discuss this project in this thread of the CPCWiki board.

Digiblaster v3

Amstrad CPC, Hardware 2 Responses »

Jul 012010

Bryce just finished his version of the Digiblaster – if you don’t know it – it is a device which is connected to the printer port and can play 8-bit samples which can be directly send to the printer port. He improved the v2 design be a R2R-resistor ladder (you needn’t to buy non-standard resistor values anymore), is now brought to stereo line-out level (you should use your active speakers now) and you can connect the output of the CPC to it (it will mix the signal of the soundchip to the sample output). He also designed two versions of the Digiblaster v3: one for CPCs with edge connectors and one for CPCs with centronics connectors.
Like with the PS2Mouse adapter, Bryce published the schematics and board layout in the [[Digiblaster#DigiBlaster_V3|CPC Wiki]].

Eliot’s hardware webshop

Amstrad CPC, Hardware 4 Responses »

Jun 252010

Elit started a small CPC hardware webshop which will offer often used parts for the CPC and other 8bit related computers. Currently you can get switches, drive belts and connectors (centronics and edge). However, it is possible that in the future you can order CPC related hardware kits.
Because some of the parts are very rare, you only should order them if you really need them and please don’t resell the parts you ordered on this site.

ACID protection decrypted

Amstrad CPC, Hardware 1 Response »

Feb 172010

I already wrote a news article about the search on how to decrypt the ACID protection of the Amstrad Plus computers. Now NoCa$h, also known for his No$cpc emulator for DOS, received a Amstrad CPC Plus cartridge by Fano and decrypted the ACID protection of the cartridge within a few days. To do this, he desoldered the ACID protection chip from the cartridge and connected it to the printer port of the PC. With a small program he sent data to the chip and tried to find a way to reproduce the signals of the chip. He found an algorithm which produces the same sequence.
With the decryption of the chip, the last big unknown mystery of the CPC is now resolved. In the future we can produce new cartridges for the CPC Plus and maybe someone will develop a reprogrammable cartridge.

You can find the pseudocode in the thread about the ACID protection in the CPCWiki forums and this information will also be included in the [[ACID|CPCWiki article about the ACID protection]] in the future, too.

;ACID reverse-engineered 13-16 February 2010 by nocash (Martin Korth)
;below is repeated on every CLK cycle...
CmpVal=13596h, XorVal=0c820h
if PinA0=1 then CmpVal=CmpVal XOR 0000ch, XorVal=XorVal XOR 00004h
if PinA1=1 then CmpVal=CmpVal XOR 06000h, XorVal=XorVal XOR 06000h
if PinA2=1 then CmpVal=CmpVal XOR 000c0h, XorVal=XorVal XOR 00080h
if PinA3=1 then CmpVal=CmpVal XOR 00030h, XorVal=XorVal XOR 00020h
if PinA4=1 then CmpVal=CmpVal XOR 18000h, XorVal=XorVal XOR 08000h
if PinA5=1 then CmpVal=CmpVal XOR 00003h, XorVal=XorVal XOR 00000h
if PinA6=1 then CmpVal=CmpVal XOR 00600h, XorVal=XorVal XOR 00000h
if PinA7=1 then CmpVal=CmpVal XOR 01800h, XorVal=XorVal XOR 00800h
if PinCE=0 AND (ShiftReg OR 100h)=CmpVal then ShiftReg=ShiftReg XOR XorVal
NewBit=ShiftRegBit0 XOR ShiftRegBit9 XOR ShiftRegBit12 XOR ShiftRegBit16
ShiftReg=(ShiftReg SHR 1) + (NewBit SHL 16)
Wait for falling edge on PinCLK
if PinCCLR=0 then ShiftReg=1FFFFh      ;\done at falling CLK edge
PinSIN=ShiftRegBit0                    ;/
;Mind that above is a software example - a hardware solution obviously
;wouldnt require CmpVal and XorVal registers - instead, hardware would
;directly deal with the PinAx (or NOT PinAx) signals.

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