64 kB Expansion RAM cartridge board

MSX 64 kB Memory expansion circuit board, assembled and tested.

  •  This product
  •  Packaging (front)
  •  Packaging (back)
  •  Fits Konami-style cartridge shells (not included)
  •  Example use with Sony HB-10


This is a MSX 64 kB Memory expansion circuit board, assembled and tested.

  • 64kB RAM (fills one slot completely with RAM)
  • PCB: 65.5mm x 43mm, 30° bevel, 2U" immersion gold.
  • Cartridge shell: Not included. Designed for Konami-style cartridges.

Use this product to upgrade an MSX 1 computer with less than 64 kB of RAM to 64 kB.

Example use: The Japanese Sony HB-10, which only comes with 16 kB, can be upgraded to 64 kB with this board.


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In stock : Ships within 5 business days unless noted otherwise (out of stock, pre-order, holidays, etc).
DescriptionMSX 64KB Expansion memory cartridge board

We normally ship within 5 days (excluding week-ends and holidays) after payment.
Prices are in US dollars and are subject to change without notice.


Q: BASIC only shows 28815 bytes (up from 12431 bytes or so) when I just added 64 kB of RAM!? Is something wrong?
A: No, this is perfectly normal. The CPU can only access 64 kB or memory (ROM or RAM), and 32 kB are occupied by the BIOS and BASIC ROM. BASIC uses a bit of the remaining 32768 bytes of RAM so in the end only 28815 bytes are free for the user.

Q: If BASIC can only use 32kB of RAM, what's the point of a 64kB RAM expansion?
A: This is mostly a limitation of the BASIC environment, where the BASIC and BIOS ROMs occupy pages 0 and 1. Once loaded (or while loading) games or software may arrange to have a different slot (such as the slot where this expansion was inserted) accessed through page 0 and 1 and therefore use more RAM.