32kB RAM & 32kB ROM

ROMRAM-side.jpg Solderless sideways ROM/RAM module for the Acorn BBC Model B

Introduction

This upgrade for the Model A/B provides sideways RAM and sideways ROM in a single module. It has 32kB of static RAM on board and a socket on the top to install a 8/16/32kB ROM/EPROM. Upto four modules can be installed in the computer for a total of 128kB sideways RAM and 128kB sideways ROM.

What is a paged ROM?

This adapter is ideal for people who want to keep their BBC as original as possible but expand it to make it more useful. Or people who want a simple plug and play memory expansion for the Model B.

Module Description

This adapter is designed to fit in one of the four ROM sockets on an unexpanded Model B. It has a 32kB surface mount static RAM chip on the bottom and a standard 28 pin ROM socket on the top. The ROM socket will accept 8kB, 16kB or 32kB ROM/EPROMs. In total it provides 2x 16kB banks of sideways RAM and 2x 16kB paged ROMs from one physical socket in the Model B.

The adapters are physically narrow so multiple modules can be placed in adjacent sockets. They have a low vertical profile so when a ROM is installed in the 28 pin socket there is still clearance to the BBC's keyboard which overlaps the paged ROM sockets (Unlike WE Quest Paint I own which actually hits the keyboard!).

Usage scenario

A typical use would be to remove BASIC, fit the adapter then refit BASIC in the adpater socket. The BBC will now have two banks of sideways RAM without using any extra motherboard paged ROM sockets.

If you have access to an EPROM programmer you could program BASIC and DFS into a 27C256 (32kB EPROM) and install that in the piggy back socket. The machine would have BASIC, DFS and 2x 16kB sideways RAM with 3 free paged ROM sockets!

Features

  • Solderless - no permanent modifications required
  • Jumperless - no configuration required
  • Occuies one paged ROM socket on a model B
  • 2x 16kB sideways RAM (32kB total)
  • ROM socket accepts 8kB, 16kB or 32kB ROM/EPROM (upto 2x paged ROMs)
  • Software controlled RAM write protect - no drilling the case to mount switches
  • Ultra low power & heat - negligible stress on the power supply

Kit Contents

Installation is very simple, solderless and completely reversible. The kit contains everything needed.

  • 32 kB ROM/RAM module
  • 2x IC clips for write strobe (NWDS) and ROM select (ROMSEL)
  • 2x wires to daisychain multiple modules
  • Printed step by step instructions

Where to buy?

The modules are available for sale on eBay or direct through this website.

Contact me for more information