TEXAS TI-74 BASICALC & 8K RAM Cartridge teardown

[jebem]

Main hardware components listing:

On the CPU PCB:
- C70009 CMOS SoC: 8-bit TMS70C46 microcomputer, 4KByte PROM, 128-Byte RAM, 8-bit timer/counter with 5-bit pre-scale register, from Texas, DIP54, dated as 1985
- HN61256PC93: 32KByte CMOS PROM 4uS max access time, DIP28, from Hitachi Japan, (c) Texas, dated as 8707
- HM6264LP-15: 8KByte CMOS SRAM 150nS max access time, DIP28, from Hitachi dated as 8703
- SI7660CJ: CMOS Switched Capacitor Voltage Converter (typ. 12Khz), DIP8, dated as 8706
- RC4193N: Switching Regulator (typ. 75Khz), DIP8, dated as RC706

On the Keyboard/Display PCB:
- HD44780 LCD Controller, FP-80B, from Hitachi
- HD44100 LCD Driver, FP-60A, from Hitachi

The internal 8KByte constant memory uses a regulated power supply that is maintained when the console is powered off.

The single line 31 5x7 dot matrix characters LCD display with 14 annunciators requires a total of 1280 pixel elements driven at 1/5 bias, 1/16 duty cycle multiplexed drive, with 16 column drive connectors and 80 segments drive connections.







(to be continued)