By far the most common are the ROM/RAM cartridges which allow easy loading and removal of extra memory without having to take the lid off the machine, overcoming the limited number of sockets on the main PCB and approaching the operating system limit of a maximum of 16 sideways banks at once.
However, actually finding a supply of cartridges has become increasingly difficult as they have often become lost or damaged over the years.
Fortunately the design for a ROM/RAM cartridge is simplicity itself, requiring only minimal chip select logic, because the expansion card interface is almost a raw copy of the 6502's system bus.
While the official ROM cartridges also came in matching a beige plastic case, the cartridges offered here further reduce complexity by making the PCB the shape of the cartridge itself - thus eliminating expensive plastic tooling costs. This also means that no screwdrivers are required to dismantle and change the chips over.
In the default configuration the cartridge behaves like the original Acorn adapter, though the extra functionality requires the changing of one or more of the onboard 3 option links:
| L1: | L2: | L3: | Comments: |
| North | North | North | IC1=8k ROM, 16k ROM IC2=disabled |
| North | North | South | IC1=32k RAM (Master only) IC2=disabled |
| North | South | North | IC1=8k ROM, 16k ROM IC2=8k ROM, 16k ROM |
| North | South | South | Invalid combination |
| South | North | North | IC1=32k ROM, half 64k ROM IC2=disabled |
| South | North | South | Invalid combination |
| South | South | North | Invalid combination |
| South | South | South | Invalid combination |
Boards use high quality turned pin IC sockets to reduce strain when inserting and removing devices, and to improve contact reliability over leaf style IC sockets.
The card edge fingers are gold plated to reduce contact resistance and oxide build up which would otherwise lead to poor contact and unreliability.
The cartridge slot nearest the keyboard provides ROM numbers 2 & 3, and the cartridge slot at the back of the case provides ROM numbers 0 & 1. Please note that when used with an Acorn Electron the cartridge cannot be configured with the 32k RAM option because the read/write signal (on cartridge connector pin A11) is wired differently to a BBC Master, therefore only ROM chips may be used.
These cartridges are available now, and are offered in various different options depending on the application:
| Option: | Price: | Comments: | ||||||
| Default configuration |
| With L1=N; L2=S; L3=N Supplied with instruction leaflet | ||||||
| 32k RAM configuration (Master only) |
| With L1=N; L2=N; L3=S Complete with 62256 low power SRAM Supplied with instruction leaflet | ||||||
| Non default configuration |
| Custom link changes Only applies at time of supply Please allow an extra 7 days for delivery |
