Amstrad 464plus Upgrade: Part 1 (128KB RAM)

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The Clueless Engineer

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Published on October 28, 2023 8:43:10 AM ● Video Link: https://www.youtube.com/watch?v=sGt7dbvsk6k

Duration: 21:15

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The Amstrad [CPC] 464plus and 6128plus use the same motherboard, with just the extra 64KB of RAM and the disk interface unpopulated on the 464 board.

The upgrade of the 464plus from 64KB to 128KB is pretty trivial - some passive components and the two 41464 (64k x 4bit) DRAMs:

R28 ... 10KΩ
R55 ... 33Ω
C12 ... 100nF
C13 ... 100nF

I used a diagnostic program that verified that all eight (00 to 07) 16KB banks were okay ... totally 128KB. A true test will be loading a 128KB-only program ... usually these only come on disk (or DSK image).

A good summary of the upgrades is here:
https://www.cpcwiki.eu/index.php?title=464Plus_Conversion&oldid=105769

I also made up an RGB cable (RGBS to 8-pin DIN) ... I included the L/R audio as well but, in hindsight, this was unnecessary, so will probably make up another cable sans audio.

{Yes, the date stamp on the intro is wrong ... filmed on Fri 27-Oct-2023 and Sat 28-Oct-2023}