Twenty pins around a kilobyte of program memory looks like an imbalance until you count the I/O: this part exists to give a small program a lot of pins. The PIC16F527 keeps the 1024-word flash array, 68 bytes of RAM and three 8-bit converter channels of its 14-pin sibling, and spends the extra six pins on portability.
The Same Core, Six More Pins
The die family is shared with the 526, and the difference is the package and the pins it exposes. More I/O means the firmware can drive a display, scan a keypad or talk to a parallel device without an external latch, and that is why designs land on this part rather than the smaller one.
For a read the difference is small. For a rebuild it is significant: a 20-pin board exercises pins that a 14-pin board leaves unconnected, and a reconstruction tested only against the smaller package will miss them.
Three Channels On A Wider Body
The converter keeps its three inputs at eight bits, and the reference behaviour is unchanged. What changes is how close the analogue pins sit to switching outputs: on a 20-pin package the layout has more room, and crosstalk that would ruin a reading on the 14-pin board may be absent here.
We verify the channels the same way regardless — two levels per input, other channels quiet, codes recorded — and we add a check with a nearby output switching, because that is the condition the product will actually see.
What A Kilobyte Of Logic Looks Like
Twenty pins and one kilobyte is a pattern that shows up in appliance controllers and simple instruments: a state machine, a scan routine, a display refresh, and a handful of thresholds. The code is dense and the tables are small.
On this part the tables are the interesting content, because they encode the product’s behaviour. We extract them as CSV alongside the listing, and we mark which table is indexed by which input, so a customer can reconstruct the specification from the image.
Why The Extra Pins Are Not Free
Twenty pins mean a larger package, more board area and more routing, and designers only accept that when the product genuinely needs the I/O. In practice it means a display, a keypad or a host interface, and each of those brings its own timing requirement into the firmware.
So the image on this part is busier than on the 14-pin version even though the array is the same size. There is less room per function, the loops are tighter, and the tables are shared between tasks.
A Table Is A Specification
On a controller like this the transition table and the threshold table together describe what the product does, in a form more precise than any document that survived. We extract both, label the index and the value ranges, and hand them over as CSV.
Customers use them in two ways: to build a fixture that drives the rebuilt part through every state, and to write replacement firmware if they decide not to rebuild the original.
Reading And Rebuilding
The 20-pin package opens with a wider window than the 14-pin one and the die is the same size, so the etch is straightforward. The array is swept twice, the configuration word is decoded, and the device ID is recorded.
On the rebuild side the pin count is the risk. We produce a pin map for the 20-pin package and test every pin, including the ones that are unconnected on the donor board, because a reconstruction that leaves an unused pin as an input can back-drive a signal the product expects to be driven.
Delivery
Binary, HEX with configuration, a listing with tables extracted as CSV, a full 20-pin map with direction states, and the three-channel record. Customers replacing this part in a shipping product usually want the pin map more than the disassembly, because the replacement rarely has the same package.
The 14-pin version of the same core is the PIC16F526 page, the low-voltage variant is the PIC16LF526 job, and the larger 18-pin part with a real EEPROM block is the PIC16F84A page. Quotations go through the services desk.