Holborn
- https://technischmuseum.nl/devices/Holborn%20computers/Holborn%20computers.html
- https://technischmuseum.nl/devices/Holborn%206100/Holborn%206100.html
- https://technischmuseum.nl/devices/Holborn%206500/Holborn%206500.html
- https://technischmuseum.nl/documentation/documentation%20files/Holborn
- http://www.cpm.z80.de/randyfiles/DRI/ASM.pdf