This is the kind of thing i might normally post on the Halfbakery, but i sort of feel it's inappropriate there so i'm putting it here instead.
The Hyperpack is a peripheral which can be plugged into the edge connector of a ZX81. It consists of two separate systems, one of which enhances the hardware of the ZX81 itself, the other of which is a device which updates the computer to be able to use today's hardware. I'm wondering if this could be a Raspberry Pi-based project, though the Pi would need to be modified.
The ZX81 is set up as usual with the Hyperpack plugged into the edge connector like a RAMPack would have been. It's battery powered but also has a charger - it doesn't use the power tracks from the computer as this would be insufficient. An MP3 player is also plugged into the ZX81 microphone and loudspeaker socket. This contains two files, of which more will be said later.
On being turned on, the computer is able to use some of the hardware on the Hyperpack but still functions as a normal ZX81. It has 64K RAM with a pageable segment allowing access to a further 16 Mb. Aside from that, it's the same as any standard ZX81.
The first file on the MP3 player is simply a decompression and higher baud rate cassette interface which loads the second file. This provides the software which allows the computer to interface with the extra hardware on the Hyperpack. There are several options on this software:
1. Return control to the ZX81.
2. Use the ZX81 as a 32x24 cursor-addressable terminal or a similar terminal with a user-definable virtual screen size with the 32x24 display acting as a scrollable window. ASCII characters absent from the ZX81 character set are represented by characters in the character set itself and lowercase is converted to upper.
3. Use the screen as a somewhat magnified scrollable window of a full ASCII text screen with graphics, represented thus: The ASCII characters are represented by the 2x2 pixel graphics characters forming a 6x7 grid. The graphics are represented in greyscale simulated by using the 128 characters available to indicate different value over several pixels.
4. Same again but as a way of displaying images.
5. Similar to (4) but represents video.
The ZX81 therefore acts as a user interface to the main part of the Hyperpack hardware. Software includes a text-based web browser, telnet, FTP, POP3, access to Twitter, Facebook and probably other things by SMS, a video player, an ebook reader, a graphical browser and an image viewer which handles JPEG, GIF, BMP, XBM and PNG files. The hardware includes a relatively large amount of RAM (possibly 256 Mb), a micro-SD card reader, a USB, RJ45 connector for Ethernet (i'm aware this is not the official name), Wi-Fi, SIM card facility and the equivalent of mobile 'phone access.
This device can therefore be used to watch videos without sound, view images, edit both, access the internet in various ways, send and receive text messages and edit text.
The point of all this is just a ridiculous nerdy coolness.