🇺🇦 Орель БК-08 (Oril BK-08): Part 4 [TCE #0508]
23The Oril is a Soviet/Post-Soviet Ukrainian Sinclair ZX Spectrum clone running the East German (DDR) clone of the Z80.
I was hoping to add a floppy disk controller in this video ... but ... this machine, that was working fine in Part 3, now no longer does.
I'll check out my other two machines to see what their status is - apparently one of the others was working but had no keyboard detection ... ?
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From Part 2:
Checked the schematics (link below, djvu format) - the internal switching regulator provides +5VDC and +12VDC to the system. The available schematics aren't very good quality - tempted to buy a NOS machine just to scan in higher quality ... {June-2023 ... done! See below}
https://speccy.info/Орель_БК-08
https://djvu.sourceforge.net/
The 2nd machine has a genuine Zilog Z80 and so I suspect both machines are using 2.54mm pin spacing rather than traditional Soviet 2.5mm pin spacing - for the main chips at least. A genuine Zilog Z80 does fit in the same socket as the DDR clone.
The machine with the DDR clone Z80 doesn't boot properly - multi-coloured garbage on the screen ... DRAM issue in ZX Spectrums?
The machine with the genuine Zilog Z80 boots to the welcome screen ... "Бейсик - Система Вер. 2.0" ... "BASIC System Ver. 2.0" ... but doesn't respond to any keyboard interaction.
So some further work to do:
[1] image the ROMs and burn copies,
[2] figure out why the keyboard isn't working (issue with the K155ЛП9/K155LP9 buffers used in place of the usual diodes?),
[3] figure out the DRAM (?) issue.
Video cable pinout (7-pin DIN):
Pin 1 = audio
Pin 2 = synch
Pin 3 = blue
Pin 4 = green
Pin 5 = red
Pin 6 = ground
Pin 7 = +12VDC (not connected in my case)
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Documentation & schematics are available here:
{5-June-2023 ... in progress}
https://archive.org/details/orel-bk-0...
Other videos in this series:
• 🇺🇦 Орель БК-08 (Oril BK-08)
Music by Karl Casey @ White Bat Audio
https://karlcasey.bandcamp.com
/ @whitebataudio