Commodore 796M
Manufacturer: | Commodore Business Machines (USA/Hong-Kong) |
Mfg. date: | 1976-77 |
Size: | 6,4×13,7×2,4 cm |
Weight (ready for operate): | 110 g |
Type: | four-function |
Capacity: | 8 digits (input/display) 8 digits (internal precision) |
Operating logic: | algebraic |
CPU: | MOS MPS7560 |
Registers: | 2 standard (with saving the pending operation) 1 memory (without arithmetic) |
Features: | %calculation with percent Ffloating-point notation |
Display: | 9 digit LED |
Power: | 9V battery or adaptor |
Technical Details
The first series were built with GRBP-67 (7-digit machines) or GRBP-89 (8-digit machines) CPU, which needed another chip to connect to the LED display. In addition to the functions available on these calculators, GRBP circuits are capable of register exchange, reciprocal and square calculations.Later series are made with the 3D-98MT (MPS7560) circuit, which can now be directly connected to the display. This made it possible to mount the chip and LED display on the keyboard printed circuit. This IC was designed for a wide range of calculators, so memory operations can be accessed with a single key M or the standard four-key solution (M +, M-, MR, MT).
Interestingly, the later series of the 786D incorporated the 3D-98MT circuit as well as the 9-digit versions, but the connection to the first digit has been cut, which means that there is not any sign of error or negative sign for 8-digit numbers. Instead of register-exchange key, it had memory key. When the missing connection was restored, this calculator become a full-function 796M model.
The lower-capacity versions were built with lower-capacity displays and, on the other hand, partially defective ones that has errors on leftmost digits only. The machines use a variety of compatible types of displays and drive circuits, so easy to find Bowmar's Optostic displays as well as in-house pieces.