Amstrad Cartridges: Part 1

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The Clueless Engineer

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Published on October 29, 2023 2:31:52 AM ● Video Link: https://www.youtube.com/watch?v=C4gCIHaJQwU

Duration: 2:20

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Each Amstrad CPC Plus machine (and GX4000) requires a cartridge to boot - they have no internal ROM. I've got a 464plus and 6128plus and so have two copies of the pack-in "Burnin' Rubber" cartridge which also contains Locomotive BASIC 1.1.

One of the cartridges doesn't seem to work so I figured I might as well pull it apart and have a look inside.

This particular cartridge contains a 27C1001 (1 Mbit/128 Kbyte) EPROM ... not a masked ROM. It also contains the Amstrad 40908 "Amstrad Cartridge Identification Device" (ACID) chip which is used as a protection mechanism to prevent unauthorised cartridges/ROMs:

https://www.cpcwiki.eu/index.php?title=Amstrad_Cartridge_Identification_Device&oldid=99901

It is possible to re-use the cartridge for any other ROM (the ACID is not tied to the ROM contents), but its operation has also been decoded (refer link above) so there are alternatives (CPLD), including a workaround that takes advantage of a timing bug apparently.

In this case, I don't know if the cartridge isn't working because of the ROM or because of the ACID, so will investigate further ... just out of interest.