Alternative method of upgrading a B+ 64K to 128K

Here's an alternative method of upgrading a B+ 64K to 128K.

Its simpler than the Acorn upgrade, and 100% compatible.

You now have a three high ROM module, with 4 'ezihooks' attached.

Photo of installed module, click for a bigger version

To use it:

Job done, and you've got an extra 32K of sideways RAM too!

Close up of location of pin 20 ezihook connections, click for a bigger version

Note that unless you have a version of the DFS ROM with the SRAM commands in, your startup banner will still say "Acorn OS 64K", as the code to include the sideways RAM in the startup banner is in the newer versions of the DFS ROM. The DFS 2.26 ROM (available from the BBC Lives page here) is known to work.

The utility available here will check for Sideways RAM banks. If your RAM is installed correctly it should detect RAM in banks 0,1,12,13 and two other banks, depending on which socket you installed the module in.

The official Acorn 64k upgrade fitting instructions at the 8BS website contains an SSD image that will test the SRAM operation, this would be another useful tool to use to check the operation of your upgrade

Also of interest on the 8BS site is the BBC B+ 128k Additional User Information document, which documents the sideways RAM commands and the "BAS128" sideways RAM Basic version

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