Texas Instruments TI-500

This rare TI-500 was introduced in the year 1974 and seems to be a sibbling of the TI-450 and TI-620.The TI-500 uses a calculator architecture based on the TMS02xx/TMS03xx family but misses the usual 12-digit display. Related calculators using this chip set are the SR-20 and SR-22. The first usage of the chip set was the TI-4000 and the Canon 121F. The architecture found in this TI-500 differs greatly from other calculators, it uses two Data-Chips (TMS0203, TMC0221) and one ROM-Chip (TMC0305). A possible reason could be found in the efforts to control the drum printer.