I worked with a programmer who cut his teeth on ancient iron in the 1950s. He had a computer that had 4K of ram and two 512 byte I/O buffers. He would set the l

I worked with a programmer who cut his teeth on ancient iron in the 1950s. He had a computer that had 4K of ram and two 512 byte I/O buffers. He would set the loader for the program into the I/O buffer and then use that to load and initialize the rest of the program. The I/O buffers would go away on the first read/write. Every byte counted. I used the same techniques when I wrote MASM in the 1990s to create a 16k I/O buffer in the CGA graphics card. The graphics card memory was slower than regular memory, but the 16K made the program fly on reads and writes. I remember a utility that used the Hercules Video card memory for EMS (paged) memory. I think it came with the card.