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Soemtron ETR220 - Apollo Era Desktop Calculator... from the GDR!
This has been a major restoration project in my lab for the last year - and now that I got the whole "cage" a.k.a. arithmetic logic unit, I could finally get the thing working. I learned a lot of stuff on diode & transistor logic, ferrite core memory, digital electronics in general...
It's technically made in the 1960s/70s (1966-1977), so Apollo time... all this while my side of the world ran on discrete germanium transistors and ferrite core memories.
Visit the excellent https://soemtron.org/ for tons of schematics and other info! Mike Hatch is a brilliant guy to have gathered and shared all the knowledge he could find in Sömmerda.
0:00 Intro
1:15 Operating the Soemtron... and Story Time!
11:40 What's Inside
13:55 The Arithmetic Logic Unit (ALU)
14:15 Ah, The Memories!
16:10 Ferrite Core Memory Addressing Control Board
19:30 My Soemtron Repair Story
23:30 Voltage Levels and Diode/Transistor Logic Explained
23:50 Flip Flop and Differentiating Circuit Explained
28:35 Ferrite Core Memory Construction and Organization
33:20 Ferrite Core Memory Operation Explained
37:00 Memory Addressing in Soemtron
41:20 On Eastern Bloc Electronic Engineering... and Nixie Multiplexing Control
46:08 For Die Cast Alumin(i)um Afficionados
47:00 Lifting the Front Cover
48:15 VEB Büromaschinenwerk Sömmerda - East German IBM?
49:15 Nixies and Lightbulbs
50:20 Decimal Point Selection Switch and Keyboard
52:40 Recombobulation
53:55 Mains Switch
57:20 Mains Plug
58:06 Afterword... And Some More Soemtron Insights!
For some additional tech info, check out my scribbling at https://hackaday.io/project/188565-soemtron-etr220-restoration-project
Support me on my Patreon page at https://www.patreon.com/KeritechElectronics or via PayPal https://paypal.me/keritech
Instagram - https://www.instagram.com/KeriSzafir
Hackaday - https://hackaday.io/keritech
#ElectronicsCreators #Keritech #Electronics
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This has been a major restoration project in my lab for the last year - and now that I got the whole "cage" a.k.a. arithmetic logic unit, I could finally get the thing working. I learned a lot of stuff on diode & transistor logic, ferrite core memory, digital electronics in general...
It's technically made in the 1960s/70s (1966-1977), so Apollo time... all this while my side of the world ran on discrete germanium transistors and ferrite core memories.
Visit the excellent https://soemtron.org/ for tons of schematics and other info! Mike Hatch is a brilliant guy to have gathered and shared all the knowledge he could find in Sömmerda.
0:00 Intro
1:15 Operating the Soemtron... and Story Time!
11:40 What's Inside
13:55 The Arithmetic Logic Unit (ALU)
14:15 Ah, The Memories!
16:10 Ferrite Core Memory Addressing Control Board
19:30 My Soemtron Repair Story
23:30 Voltage Levels and Diode/Transistor Logic Explained
23:50 Flip Flop and Differentiating Circuit Explained
28:35 Ferrite Core Memory Construction and Organization
33:20 Ferrite Core Memory Operation Explained
37:00 Memory Addressing in Soemtron
41:20 On Eastern Bloc Electronic Engineering... and Nixie Multiplexing Control
46:08 For Die Cast Alumin(i)um Afficionados
47:00 Lifting the Front Cover
48:15 VEB Büromaschinenwerk Sömmerda - East German IBM?
49:15 Nixies and Lightbulbs
50:20 Decimal Point Selection Switch and Keyboard
52:40 Recombobulation
53:55 Mains Switch
57:20 Mains Plug
58:06 Afterword... And Some More Soemtron Insights!
For some additional tech info, check out my scribbling at https://hackaday.io/project/188565-soemtron-etr220-restoration-project
Support me on my Patreon page at https://www.patreon.com/KeritechElectronics or via PayPal https://paypal.me/keritech
Instagram - https://www.instagram.com/KeriSzafir
Hackaday - https://hackaday.io/keritech
#ElectronicsCreators #Keritech #Electronics