Casio Personal M-1 (H-813)
Brief History
In the end of the 1970s, due to cheap and mass produced liquid crystal displays, calculators with traditional LED and VFD displays rapidly disappeared from the lineup of manufacturers, except for desktop models with printers, in which still used. Nevertheless, Casio kept one type in production from both the basic and scientific models until the mid-1980s. These were Personal M-1 and fx-140.
The Personal series features specifically low-cost models designed for home use. The top model in the series was the Personal M-1 with automatic accumulating memory, produced from 1976.
Its NEC chip has typical Casio features: the 8-digit machine was able to handle 7-digit negative numbers, and its constant register can be switched on with repeatedly pressing the appropriate operation key.
Due to the common circuit shared with other models, and the planned large quantities, the first version (H-813) already supported several types of displays, and over the years it received first a more modern flat display tube (H-813B) and then a simpler printed circuit (H-813C).
| Manufacturer: | CASIO Computer Co., Ltd. (Japan) |
| Mfg. date: | 1976-77 |
| Size: | 7,5×12,2×2,1 cm |
| Weight (ready for operate): | n.a. |
| Type: | four-function |
| Capacity: | 8 digits (input) 8 (7) digits (display) 8 (7) digits (internal precision) |
| Operating logic: | algebraic |
| CPU: | NEC uPD577C |
| Registers: | 2 standard (with saving the pending operation) 1 constant (with saving the pending operation) 1 memory (with arithmetic and auto-summation) |
| Features: | %calculation with percent Ffloating-point notation Sqrsquare root |
| Display: | 8 digit VFD (NEC LD8120S) |
| Power: | 2×AA battery or AD-2S adaptor |
First version of Personal M-1
Inside of the first version of Personal M-1
Keyboard of the first version of Personal M-1
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