A solution I just heard about which seems not yet to have been mentioned here is DrawBridge; it's an open source Arduino project that uses a regular PC floppy drive to read Amiga disks like many others but the really neat thing is that it's small enough to fit with the drive inside the enclosure of a regular 2021-sized USB floppy drive, as depicted here.
My FluxEngine software can read and write ADF files onto floppy drives using the appropriate hardware: either my own matching FluxEngine hardware (open source, easy to solder up from a standard cheap dev board, requires Windows to program the board) or keirf's GreaseWeazle (open source based around a Blue Pill STM32 board, harder to solder up or you can buy ...
Finally designed and built an Amiga A1050 knockoff. Seems to work well on my Amiga 1000.
Schematic, PCB and BOM is posted on github
The answers to my question are:
The black blob is indeed a 39 ohm resistor pack
C1-C8 are 0.22 uf capacitors
C9 is a 10 uf capacitor
Thank you to those who gave me ...
I remember now seeing an LGR Oddware video a few months back about an ISA card for MS-DOS PCs that allowed you to write save states. I think he demoed it on Crystal Caves but I don't recall what the product was called (probably another Datel product). I also can't remember if it saved to memory or hard disk... will try and find the video for more details.
There existed at least two such devices for the Super Nintendo:
The NakiTek Game Saver and Game Saver+.
I haven't seen a picture of the base version but the plus version is a bulky Super Nintendo cartridge with a slot on the back to plug the actual game cartridge into.
The difference between the two is that the plus version supports using AC power or AA ...
ZX Spectrum compatible Didaktik Kompakt had the ability built in - pressing CAPS SHIFT, left arrow and right arrow together saved current state to the floppy (it used a few bytes on the stack, so it could fail sometimes).
Yes, two examples of these are the Final Cartridge and the KCS Power cartrdige for the Commodore 64. Both allowed the C64 to be "frozen" upon pressing a button on the cartridge and then via a menu the state of the system could be saved to either tape or disk. These states could then at some later point be re-loaded into the system and the C64 would ...
For the Spectrum, the Microdriver (by Mirage) and the Multiface (by Romantic Robot) had the ability to save the state of memory, to cassette, Microdrive or the Spectrum +3's floppy drive. This state file could then be reloaded.
Later versions of the Microdriver also had the ability to do an uncompressed dump of memory, which was not intended to be reloaded. ...