Allow me to introduce my small (but growing) collection of solid state disk solutions for my vintage machines. Here we have an 8MB SSD that you can add to a motherboard ROM slot (or to an ISA/PCI card with a large enough slot). Big enough for a DOS system and some network drivers

The makers of that 8MB chip (M-Systems) were one of the pioneers of flash based storage solutions. Later on they made this baby, a 256MB SSD that you could plug directly into a PATA IDE slot. M-Systems were later acquired by SanDisk.

Moving into somewhat more conventional territory, here's a 512MB SD card on an IDE adapter, and then a conversion board from laptop 44 pin to desktop 40 pin + power. I use the 512MB card because that's the maximum my 386 can address without additional extensions.

(here it is from the other side just in case someons is curious)

And this is a CF card to IDE converter. It seems that CF cards are basically just IDE anyway since the card doesn't have any meaningful electronics on it like the SD -> IDE converter. These were quite popular in the early 2000s when people wanted to build a quiet machine.

And for transferring stuff to old laptops (that doesn't have USB/ethernet and hard to remove hard disks), this comes in quite handy, a CF card to PC Card adapter.

This is an M.2 to 44 pin IDE converter. It relies on the last generation UDMA chipsets that existed so I think it basically just works on P4 machines and machines from that era. This M.2 chip is 256GB which is plenty for an old machine that still takes IDE disks.

Another old SSD for my collection. Probably my smallest yet. This SSD is only 2MB in size, not all that useful as a full hard disk, but could still be a fast boot drive for DOS.