Comments on Calculator Technical Data
Technical data relating to particular calculators has been categorized into 3 levels to indicate the depth of data available:
- Level 0: None
- Level 1: Basic observable characteristics such as IC complement, display type, etc.
- Level 2: Complete schematic. In the case of SSI/MSI based calculators this includes pinouts for integrated circuits.
- Level 3: Full understanding and description of the state machine and internal functioning.
A value with a fractional component indicates the approximate portion of the level available. For example, 2.5 means level 2 (the schematic) is complete and about half of level 3 has been derived.
For levels 2 and 3 the source of data may be either reverse engineering or manufacturer data.
With a few exceptions, levels 2 and 3 data presented here (including pinouts for integrated circuits) has been derived from the reverse engineering of various calculators.
For LSI-based calculators a maximum of level 2 will be available without manufacturer technical data.
Comments on Reverse Engineering
With patience, perseverence, and an excessive amount of time on one's hands, reverse engineering can
produce an accurate schematic of connections.
If the IC-pinouts are available then producing the logic schematic from the connection schematic is trivial.
However, if the IC-pinouts are not available, then one must derive the pinouts from the connection schematic.
This becomes a specialised puzzle which can be solved with:
- knowledge of binary logic and the building blocks of such
- knowledge of electronic gate construction
- a perspective on the IC technology and practices of the time
Viewing the unit in terms of it's functional structure and working from the 'outside' (I/O devices: keyboard, display, clock) to the 'inside' (registers, arithmetic, etc. and finally the state machine) gate inputs and outputs can be identified and with a little conjecture and iteration eventually the picture of the logic emerges.
Having now arrived at the logic schematic and IC pinouts, level 2 of the reverse engineering is complete.
This data can now be used to create a simulation of the unit. The simulation permits one to observe the internal functioning in a meaningful and controllable form, and can be used as the basis for deriving level 3 data. The simulation also provides the benefit of proving the accuracy and validity of the level 2 data.
Occasionally, in the process of attempting to identify the internal use of the pin of an IC, there is not enough information or diversity of use to arrive at a firm conclusion.
For example, the µPD106 IC in the Commodore DAC-612 is used 2 times but in both cases pins 1,2,8 and 10 are connected to ground.
As only one ground connection is necessary it is not possible to discern whether the multiple connections to ground are actually required, are inputs connected to ground as a requirement of the application, or are open pins and just acting as 'ways' for another connection on the printed circuit board. Such pins are marked with a question mark on the IC pinouts.
Key to Headings and Abbreviations
Logic Technology refers to the physical technologies used to implement the logic:
- DIS: Discrete diode/transistor.
- SSI: Small Scale Integration.
- MSI: Medium Scale Integration.
- LSI-n: Multi-chip Large Scale Integration. Calculator logic contained in a set of n LSI chips.
- LSI: Single-chip LSI. Additional driver chips may be present.
Memory Technology refers to the physical technology used to implement the main register memory:
- DELAY-MS: Magnetostrictive acoustic delay line.
- CORE: Magnetic Core.
- DIS-FF: Discrete transistor Flip-Flops.
- MSI-BIP: Bipolar transistor Medium Scale Integration.
- MSI-MOS: MOSFET transistor Medium Scale Integration.
- LSI: Memory is inside a Large Scale Integration IC.
Display refers to the type of display technology used:
- IDL: Incandescent Dot Layers. See the Canon 130 calculator.
- NIX: NIXIE
- GDI: 7 segment Gas Discharge Individual. 1 digit per vacuum envelope.
- GDM: 7 segment Gas Discharge Multiple. Multiple digits in one vacuum envelope.
- PPX1: Burroughs Panaplex. 7/8 segment gas discharge.
- PPX2: Burroughs Panaplex II. 7 segment gas discharge.
- VFI: Vacuum Fluorescent Individual. 1 digit per vacuum envelope.
- VFM: Vacuum Fluorescent Multiple. Multiple digits in one vacuum envelope.
- LED: Light Emitting Diode.
- LCD: Liquid Crystal Display.
- PRI: Printer.
TD Level refers to the depth of technical data available:
- Level 0: None.
- Level 1: Basic observable characteristics such as IC complement, display type, etc.
- Level 2: Complete schematic.
- Level 3: Full understanding and description of the state machine and internal functioning.
A value with a fractional component indicates the approximate portion of the level available.
For LSI-based calculators a maximum of level 2 will be available without manufacturer technical data.
See also comments on technical data and reverse engineering above.
TD23 Pages is the number of printed pages of level 2 and 3 technical data (primarily the schematic).
TD23 Source is the source of level 2 and 3 technical data:
- RE: Reverse Engineering.
- MF: Manufacturer Data.
TD23 Data is the actual level 2 and 3 data:
- view: Presents a complete one-page schematic.
- list: Presents a list from which all pages of a multi-page schematic can be viewed.
- portion: Presents one page of a multi-page schematic, the remainder is offline.
- offline: Data not online.