@Garno - don't know what happened to the the link I posted, don't have any connection to them. Anyway here's the salient details:
AutoCAD 2020
Operating System: Microsoft Windows 10 (64-bit only), 8.1 (64-bit only), or 7 SP1 (64-bit only)
Processor: 2.5 GHz (3+ GHz recommended)
Memory: 8 GB (16GB recommended)
Disk space: 6.0 GB
Display: 1920 x 1080 resolution with True Color
AutoCAD 2019
Operating System: Microsoft Windows 10 (64-bit only), 8.1 (32-bit & 64-bit), or 7 SP1 (32-bit & 64-bit)
Processor: 2.5 GHz (3+ GHz recommended)
Memory: 8 GB (16GB recommended)
Disk space: 6.0 GB
Display: 1920 x 1080 resolution with True Color
AutoCAD 2018
Microsoft Windows 10 (64-bit only), 8.1 (32-bit & 64-bit), or 7 SP1 (32-bit & 64-bit)
1 GHz or faster processor
RAM
32-bit: 2 GB
64-bit: 4 GB
Disk space: 4.0 GB
1360 x 768 display resolution with True Color
AutoCAD 2017
Microsoft Windows 10, 8.1 or 7 SP1
Intel® Pentium® 4 or AMD Athlon™ 64 processor
RAM
32-bit: 2 GB
64-bit: 4 GB
Disk space: 6.0 GB
1360 x 768 display resolution with True Color
AutoCAD 2016
Microsoft Windows 8 or 7
Intel® Pentium® 4 or AMD Athlon™ 64 processor
RAM
32-bit: 2 GB
64-bit: 4 GB
Disk space: 6.0 GB
1024 x 768 display resolution with True Color
AutoCAD 2015
Microsoft Windows 8 or 7
Processor
32-bit: Pentium 4 or AMD Athlon Dual Core, 3.0 GHz or greater with SSE2 technology
64-bit: Athlon 64 or Opteron with SSE2 technology, or Intel Xeon or Pentium 4 with EM64T support and SSE2 technology
2 GB RAM
Disk space: 6.0 GB
1024 x 768 display resolution with True Color