Expanding from CPC 464 to CPC 6128 Spec

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Step-by-step instructions

Step 1

There are two ways to replace the CPC 464 ROM chip.

  • A. While everything is switched off and if you have the right set of tools and have any electrical knowledge, remove six screws from the keyboard and carefully take the keyboard a part. Look for the CPC 464 ROM chip with the letters printed "IC103 AMSTRAD 40009" which is already soldered onto the motherboard. Here comes a real challenge....

Firstly, you have to remove additional nine screw using a philips screwdriver. And then, you have to de-soldier all the legs from the CPC 464 ROM chip, remove it and replace with DIL Socket 28-Pin (Maplin ref no: BL21X, which it costs about 14p each - current price is now 29p each or can be purchased from eBay), making it easier to swap 464 or 6128 ROMs and visa versa, then solder all the legs from that socket onto the motherbaord.

Next, put the CPC 6128 ROM chip printed "AMSTRAD 40025 8902 B" inside the DIL 28-way socket. Put all the bits into place, put the keyboard cover back on and then put six screws back on. Now to test your handy work... After your computer powered up with all accessories, your screen should show exactly the same as CPC 6128 start-up screen.

NOTE: All versions of CPC 464 keyboards including Arnold 1 (according to comp.sys.amstrad.8bit FAQ) version with big "AMSTRAD" letters printed onto the keyboard, like the one shown on the photo - #12: 32 Kb ROM memory containing the operating system and Locomotive Basic. Also with the "Cost-Down" version as well doesn't have a socket to remove and replace Operating System ROM chips, instead all the legs are soldiered on and its impossible to remote it straight away, unless you know how to de-soldier - 31/6/05.

  • B. Simply exchange your CPC 464 keyboard to Amstrad Specialist (Arthur Cook) for another CPC 464 keyboard with CPC 6128 ROM chip fitted (That's what I did with mine on Thursday 12th Oct 2000, while I was rushing to get home from Worthing and that time, I didn't know how to replace Operating System ROMs) or ask him to do it for you and paid for it, of course.

Step 2

Now you have a choice to do one of the following options:

  • A. Replace the AMSDOS / CP/M bootstrap ROM with ParaDOS ROM inside the disc interface (it allows you to use the full capacity on 3.5" disc drive).

RECOMMENDED to do so, if you're using either:

  • Upgraded CPC 464+ to 6128+ spec
  • Unexpanded CPC 464 without CPC 6128 OS/BASIC ROM installed, having only both DDI-1 3" & 3.5" external disc drives connected.

To do that, you must remove two screws first, open the cover, carefully remove the AMSDOS ROM chip with "AMSTRAD 40009" printed on top of it and replace it with ParaDOS ROM. Then put the cover back on and put the two screws back on.

Step 3

Connect all the peripherals to "Expansion" port connector (located at the back of the keyboard) in the following order:

Step 4

Follow the "READY" signal instructions (if necessary) for 3.5" disc drive Ready signal test.

After all that, your fully expanded Amstrad CPC 464 to CPC 6128 spec set-up should look similar like this as shown below:

Upgraded Amstrad CPC 464 with available add-ons: CPC 6128 OS/BASIC ROM Chip replaced inside CPC 464 keyboard, Dk'tronics 64K RAM pack (upgraded to 256K), Rombo Rombox containing Utopia, BCPL, Maxam, Protext & ParaDos, Amstrad DDI-1 External 3" Disc Drive with AMSDOS / CP/M bootstrap ROM inside Disc Interface & modified 3.5" second External Disc Drive (NEC FD1036 A) with side switch, READY signal, built in power supply & Inter-connecting Lead with 34 way IDC Male connector.

Now you have a choice to play games or save / load programs from tape, either 3” or 3.5” discs! As software is concerned, its the same as CPC 6128 with a few add-ons included.


This idea originally comes from David Cantrell's CPC 464 at Obsolete Computer Museum but he didn't write out the instructions how to do it like I did. Its took me months of research to work out how it works on my own CPC 464 one by one and writing it out on rough paper, after I have looked at his web site for the first time and thinking that "Wow! That's what I always wanted on my CPC 464" while I was searching for Amstrad CPC 464 Specs on Internet. Now its here on this web site and I'm very proud that it works perfectly on my expanded CPC 464.

Another upgraded Amstrad CPC 464 except with dual Amstrad CPC 464 & CPC 6128 OS/BASIC ROM Chips fitted inside older CPC 464 keyboard, a 464 / 6128 Mode switch on left hand side and 2 x 3" FD-1 drives (DDI-1) - purchased from eBay on 4th March 2012. Both PARADOS ROM replaced inside disc interface & Dk'tronics 64K RAM pack (SMD version) wasn't included in the part of the package and it was purchased separately.