"G=C800:5"
Only a few of you will understand that title, but that's OK In the dark days of the early 1980's hard drives were mysterious, largely analogue devices If you look at image above the connections are very different to recent technologies, and the cables carried a mixture of analogue data and digital control signals. It's not super clear in the image, but the white label towards the back of the drive was a list of "bad sectors". Literally, these were manufacturing defects on the surface of the drive where data could not be read or written reliably. Much earlier in my career, I had to guide customers through the process of installing very expensive ten and twenty megabyte hard disks into PC-XT and PC-AT style machines. The XT style machines didn't actually understand hard disks, and relied on a BIOS extension on the controller card to do the work. BIOS extensions were one of the most brilliant aspects of the IBM PC architecture in my opinion, but that's a...