Kim-1: Memory issue fixed

In the early days of the personal computer revolution, there were relatively inexpensive boards with little more than a processor, memory, display, and switches or keyboard. Some of them had expansion ports meant for you to grow, and some were just "trainers" to learn more about computers. Although you could argue that the Altair fell into this category, it had an appropriate case and bus. The computers we think of were usually only on one board and - hopefully - had an edge slot for expansion. Perhaps the most famous of these was the KIM-1 and [Old VCR] shows us how he brought one back to life.

These were very popular mainly because of the low price of $245 in 1976. For that price you got a calculator type keyboard and LED display, 1K RAM and 2K ROM. [Old VCR] has several and noticed one had memory issues.

Basic troubleshooting revealed the culprit to be the memory chip at U10 on the schematic. Adding a good RAM chip proved the chip was to blame and of course there was no socket so surgery ensued!

On older boards, it's hard to remove a piece without leaving damaging marks and this one was no exception. The silver conductive ink fixed the trace, but the repair failed. That's when the diagnostic card - a design by [Dwight Elvey] comes in.

Spoiler alert: the culprit was a solder bridge, also easy to do on these older boards. By removing the short circuit, restore the old computer to perfect condition.

If you want your own KIM-1, you can make a modern build of it quite easily and save most of the $5000 or so a real one would cost. Or take an Arduino. If you do the latter, you can also make it a passable COSMAC elf.