Patch wires
(some examples of many)
This web page is not intended to document all known patch wiring. It exists to illustrate some patch wiring.
Early version of IBM MDA card
Photo at here.
IBM 64/256KB Memory Expansion Option
Patch wires affecting U33 and U49.
Photo at here.
I have three of these cards, and they all have this same wiring modification done to them.
IBM 5150 Motherboard of Type 64KB-256KB - Unknown Mod
A chip has been added to the U101 socket (a 'spare' position, normally empty), and wires run from that chip to other chips.
That suggests that some kind of design defect is being corrected.
Photo at here. (source: Timo W. at the VCFF)
Related discussion in posts #23 and #24 at here.
IBM 5160 Motherboard of Type 64-256KB - Unknown Mod
A chip has been added to the 'SPARE' socket (normally empty), and wires run from that chip to other chips.
That suggests that some kind of design defect is being corrected.
Photo at here. (source: nztdm at the VCFF)
IBM 5160 Motherboard of Type 64-256KB - Enhancement for ROM
At some point, IBM switched from using TMM23256/MK37000/MK38000 ROM's to using 27256 EPROM's, or equivalent.
To accomodate that change, the wiring of sockets U18 and U19 was changed. Pin 1 is no longer connected to pin 27; instead connected to the +5 volts line.
One example of the subject wiring change is at here. (Wires put on solder side.)
Another is at here. (Wires put on component side.)
IBM 5160 Motherboard of Type 64-256KB - Upgrade to Hold 640 KB
As part of the procedure of upgrading a 64-256KB type of 5160 motherboard to a 256-640KB one, pin 1 of U44 gets grounded. IBM did that by putting a jumper or wire on pins 1 and 2 of jumper pad E2, however, instead of that, a grounding technique sometimes used by others was to connect a wire between pins 1 and pin 8 of U44.
IBM CGA card - Unknown Mod
Some CGA cards have the patch wires shown at here.
IBM 5162 Motherboard - Unknown Mod
Photo at here.
IBM 5170 Motherboard of Type 2 or 3 - Unknown Mod
Photo at here.
IBM Serial/Parallel Adapter - Unknown Mod
Photo at here.
IBM Fixed Disk and Diskette Drive Adapter - Unknown Mod
Photo at here.
Motherboard of NEC PowerMate-1-Plus
Photo at here.