Hard Disk Interface for the Printer Port

Can’t even give away that hard disk drive on your redundant PC system? Why not use it as a portable drive? This interface adapter allows a standard low-cost internal hard drive to be used as a convenient mobile plug-in unit, great for storing or transferring large files from PC to PC or notebook. A preprogrammed Altera EPLD chip ensures a neat unit with a minimum of external circuitry.It’s difficult to believe that the first PC systems came without a hard disk drive. How did we ever manage? It was only when hard drives appeared that the real convenience of a PC was realised, we didn’t mind that these drives could only store a few Mbytes and were about the same size and weight as a common house brick, it was certainly an improvement on reloading MS-DOS from a boot disk at every start-up.

Resistors:
R1 = SIL array 8 x 1kOhm 
R2 = SIL array 4 x 470Ohm 
Capacitors:
C1,C3-C8 = 100nF
C2 = 100µ F 16V radial
Semiconductors:
IC1 = 7064LC84-15 (Altera), programmed, order code 010047-31
IC2 = 74HCT14N
IC3 = 7805
Miscellaneous:
JP1,JP2,JP3 = 3-way pinheader with jumper
K1 = 25-way sub-D-plug (male), PCB mount
K2 = 10-way boxheader
K3 = 40-way boxheader
2 solder pins
Extension cable for PC PSU (see text)
Printer extension cable (1:1)
IDE cable
PCB, order code 010047-1