View Single Post
Old 25th Jul 2018, 8:41 pm   #72
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
Default Re: MK14 schematic revisions

(Brought across from the 'Tesla MH74S571 Programming' thread, as it was veering well away from that specific topic)

Quote:
Originally Posted by TonyDuell View Post
...the late version PCBs could take a keyboard switch that Maplin sold (I think they called it a 'clickswitch') and of course that was mentioned in magazines at the time. Many MK14 owners fitted 20 of those with white caps for the digits and some other colour caps for GO/MEM/ABORT/TERM (where did those names come from??). Obviously you then had to label them with Letraset or similar.
I think those 'clickswitches' are what my MK14 has on the keyboard currently fitted to it, but, being an issue II it has no provision for them to be fitted on the MK14 itself.

On mine, they are fitted on a separate PCB (actually a well disguised bit of veroboard / stripboard) which is mounted directly over the original keypad position with a gap of about 3-4 millmetres between the main PCB and the keypad PCB. I really must get off my lazy rear and design a proper generic MK14 keypad PCB. If Slothie can come up with a whole MK14, I'm sure I should be able to do that one little thing. You would think nowadays that it would be trivial to get a set of keytops custom 3D printed with legends embedded in them in a secondary colour, but I don't think we are quite there yet, so it's still down to plain keytops and good old Letraset.

As I imagine you (Tony) know, but others may not, the command key names came from the development system from which the MK14 was derived, the earlier National Introkit which I believe is what we see here in this Youtube Video.

https://www.youtube.com/watch?v=fK-IZuIonnY

If you pause during close ups of the keypad you can clearly see the same Go, Mem, Abort, Term command keys.

As far as I know the monitor / OS in the National Introkit was byte for byte identical to the one subsequently used in earlier issue MK14s.

That still doesn't explain the choice of the actual words, though....
SiriusHardware is online now