Arnold (Codename)

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Arnold is Amstrad's internal codename for the CPC computers.

In the BIOS ROM the string "Arnold" is found as a (non-selectable) leading dummy-entry in the list of LK-selectable Brand Names.

The name of the character Roland (occuring in early Amsoft games) is an anagram of Arnold.

Arnold Numbers

Amstrad used some kind of an "Arnold Numbering System" for revisions of the CPC hardware. The "official" meaning of that numbers is unknown, and there a several different "homebrewn" interpretations:

Numbering for CPC Models

Arnold 1-5 are widely used to refer to different CPC models:

There are several variations: Some webpages omit the costdown CPCs (and refer to the Plus as Arnold 4). Other webpages split Plus to separate numbers (Arnold 5 for 464+, and Arnold 6 for 6128).

Numbering for Gate Array Versions

Looking closer at the two offical docs, ARN4 refers to the 100pin ASIC, Arnold V describes the 160pin ASIC. So it seems more likely that Amstrad was using the Arnold Numbers to refer to Gate Array Versions, rather than to the computer models:

  • Arnold 1 - Gate Array 40007 (old version with cooling-plate)
  • Arnold 2 - Gate Array 40008 (rare medium version)
  • Arnold 3 - Gate Array 40010 (newer version)
  • Arnold 4 - Gate Array 40226 (costdown 100pin SMD version)
  • Arnold 5 - Gate Array 40489 (plus 160pin SMD version)

Overall Numbering

Finally, it's possible that both of the above numbering systems are correct - the different Gate Array versions were developed alongside with the different computer models - so the numbers may have originally referred to both chips & computers. Although later on, the 40010 Gate Array was also used in 464/664, rather than in 6128 only.


  • Arnold 1-3 - There are no (known) official docs mentioning these numbers.
  • Arnold 4 - The 100pin ASIC chip is marked "ARN4" in costdown schematics Amendment Service Manual, page 20)
  • Arnold 5 - CPC Plus (the Original Arnold V Specs refer to the Plus/ASIC as "Arnold V")