Hi-Tek Dovetail Series
|This article requires additional photographic illustration|
|Family||Hi-Tek High Profile|
|Sense method||Metal leaf|
|Switch mount||PCB mount|
Hi-Tek Dovetail Series is a switch grid construction system designed, patented and manufactured by Hi-Tek. Hi-Tek referred to the design in their patents as a "Dovetail base assembly for keyswitches", referring to the way that switch modules physically interconnect. It is an extension of the Hi-Tek High Profile switch design. Dovetail Series seems to be only marginally older than Hi-Tek Series 725, but still saw use.
Dragon Data's Pippin, their 1981 prototype machine, used Hi-Tek High Profile switches with a "waffle frame" grid. Photographs of production Dragon 32 and Dragon by Tano computers—the former being introduced in 1982—all show dovetail base assemblies. It is likely that this change occurred at the beginning of the production manufacturing run in 1982, as despite the earliest dovetail patent found to date being filed in 1983, no waffle frame keyboards have been found in production machines, including low serial number examples.
The dovetail base assembly used in the Toptronics Sinclair ZX81 keyboard is marked with the original 1972 patent for the High Profile switches.
Lydon Davies, formerly of Dragon Data, is quoted as having said that the Hi-Tek keyboards fitted to Dragon computers cost £10 each.
On a Hi-Tek dovetail keyboard, the core key grouping is formed from a single moulding; the typical design appears to be four rows of single-unit keys, starting with 10 keys at the front, and increasing by one key per row to 13 keys in the back row. There is an 8-unit space switch bar in front in its own row, above which Hi-Tek place their branding. This design allows for a rigid block of switches to be formed from discrete switches; no mounting plate is required as the switches form a collective solid block.
Additional keys are provided by single or multiple-key modules that lock into place via dovetail joints. Larger keyboards will have clusters of isolated modules or groups of modules. These modules bear only the Hi-Tek arrow mark. Spacers allow for key positions to be further out than permitted by the standard module widths.
The switch mechanism is the same as that of the High Profile switch.
The following are referenced sources where the Hi-Tek name or logo has been found on the switches or PCB or the keyboard's origin is confirmed by a third party:
- Dragon Data 8-bit series:
- Toptronics Sinclair ZX81 keyboard (10-to-13–unit module)
- HP 9816 keyboard (10-to-13–unit module with add-on modules)
- Perkin-Elmer 3700 keyboard (non-modular keyboard with isolated add-on modules)
HP 9816 keyboard, with a 10-to-13 core module and add-on modules
Two isolated four-way modules from a Perkin-Elmer 3700 keyboard