There is a clone designed by one member of the computer staff at Portsmouth Polytechnic designed a Model I compatible clone with enhancements such as color graphics, speed up, double density, and much more. It reportedly loads Level II BASIC into RAM from disk.
The main board has the WD1771 disk controller on it and the double density controller board is a plug-in (Disk Expansion Board) which as you can see from the photos.
This page contains all the information I have on that clone.


Pictures


Schematics


  • 8255 Replacement for 68B21

  • CPU Graphics Mod

  • Disk Expansion and Clock

  • Graphics Card Schematic 1 of 3

  • Graphics Card Schematic 2 of 3

  • Graphics Card Schematic 3 of 3

  • Memory Board Connector Wiring

  • Memory Board Schematic 1 of 2

  • Memory Board Schematic 2 of 2

  • Rear Panel Board

  • Z80 CPU Board Paged ROM/RAM over BOOT/ROM

  • Z80 CPU Board

BOM’s


  • Disk Board

  • Graphics Board

  • Memory Board

  • Rear Panel

  • Z-80 CPU Board