The ZXpand interface is a brand new interface for the Sinclair ZX81, and Timex-Sinclair TS/1000 Home Computers.

The ZXpand interface offers 32K of expanded memory (which is configurable to support various hi-resolution graphics modes), instant file access to .p files stored on SD memory cards and more.

The Sinclair ZX81 ZXpand interface will also allow you to connect an Atari style 9 pin joystick port to play either specially written or specially adapted games.

The ZXpand provides the following facilities:

• SD Memory Card reader – for instant loading from / saving to .p files (used by ZX81 emulators)
• 32K of configurable RAM memory, which can then be set up to use the various hi-resolution graphics schemes for the Sinclair ZX81.
• New keywords are added to the system ROM to allow you to load and save programs, produce a catalogue of files on the memory
  card, configure the ZXpand Interface, and delete files.
• You can still load programs from cassette as well as using the interface, to allow you to copy files onto the SD memory card.
• Sub-directories are supported on the memory card.
• The new ROM can be switched off once a program is loaded, in order to allow access to LPRINT, LLIST and COPY commands.
• There is a built in reset button to reset the ZX81 without having to pull the power lead.

Download: ZXpand Manual (2392)

source: rwapsoftware.co.uk