UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - MK14 programming interface

SiriusHardware · 14th Mar 2019, 2:16 am

Something which just occurred to me: I did all my testing and tuning of the 'V2' interface and 'send14' Python script with my own MK14 which has the original 4.43Mhz crystal in it.

The values of the time delay constants 'KeyPressLength' and 'KeyReleaseLength' and 'ModeChangeSettleTime' (defined early on in the script) are pared down to almost the smallest values consistent with 100 percent reliable input, in order to obtain the highest possible upload speed.

If your replica MK14 or original MK14 happens to have a 4.00MHz crystal fitted (...original MK14s often had the crystal changed to 4.00MHz when a VDU was added) it will be running slightly more slowly and these timing values may need to be adjusted upwards slightly for 100% error free operation. Unfortunately, I can't check this by fitting a 4.00MHz crystal myself because the tracks on my (original) MK14 are quite fragile.

14th Mar 2019, 2:16 am	#20
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,560	Re: MK14 programming interface - MK2 Something which just occurred to me: I did all my testing and tuning of the 'V2' interface and 'send14' Python script with my own MK14 which has the original 4.43Mhz crystal in it. The values of the time delay constants 'KeyPressLength' and 'KeyReleaseLength' and 'ModeChangeSettleTime' (defined early on in the script) are pared down to almost the smallest values consistent with 100 percent reliable input, in order to obtain the highest possible upload speed. If your replica MK14 or original MK14 happens to have a 4.00MHz crystal fitted (...original MK14s often had the crystal changed to 4.00MHz when a VDU was added) it will be running slightly more slowly and these timing values may need to be adjusted upwards slightly for 100% error free operation. Unfortunately, I can't check this by fitting a 4.00MHz crystal myself because the tracks on my (original) MK14 are quite fragile.