TEXAS TI-74 BASICALC & 8K RAM Cartridge teardown

[jebem]

I got this popular machine (among many Texas fans, that is) stored in a box for too long.

Some time ago I have acquired a 8K RAM module and decided to test it.
I have inserted a set of cheap IKEA batteries and all went fine with the testing.
And then I forgot the machine in a drawer for a couple of months.

Recently I realized my mistake. This happens to the best, doesn't it?
In the very second I powered it on and it stayed dead, I understood that the internal memory (and something else) had depleted the batteries. Or maybe the cheap batteries should not be forgotten inside cherished electronic devices.
And of course it was too late. The battery electrolytes were all over the place.
So it was time to teardown this machine and have a proper cleaning.

Here are some basic specifications taken from the Texas official documentation:

- ANSI BASIC programmable and scientific calculator with 8KByte internal constant memory (7.5KByte available to the user), extended to 16KByte with a 8KByte constant memory removable cartridge.

- Power supply: 4 x AAA alkaline battery cells, or 6.3V DC external supply to pin-2 of the I/O port.

- BASIC programability:
Close compliance with ANSI BASIC with enhanced feature tailored to a portable calculator.
Numeric or BASIC line less expressions are executed in immediate mode.
Radix-100 floating point numbers using 8-Bytes per number. 1-Byte for exponent and 7-Byte for up to 14-digits BCD mantissa.

- CI-7 Audio Cassette Interface for data and programs off-line storage.

- PC-324 24 column thermal printer.

- The 8KByte RAM cartridge can be set as Constant Memory for data and programs, or set for 8KByte Mass Storage device.

- Optional 32KByte ROM Cartridges with applications from several suppliers.
Optional EPROM Cartridges for low volume applications.

- Scientific calculator mode
13 digit accuracy, logarithmic, hyperbolic and trigonometric, 2-var statistics, and probability functions. 10 user registers. Alphanumeric error messages.







The removable cartridge with 8KByte RAM.



(to be continued)