Tony D. wrote, in response to a message about the Wang 100-series
calculators that I wrote a while back
Please don't murder me. I was young and foolish... I have the remains
of those somewhere :-(
I understand. We all make mistakes, especially when we are younger. I
made my share of mistakes back in the day too...though it's not like the
days of mistakes are gone despite my age and supposed wisdom :-)
These are extremely rare machines today. They were kind of a lost
machine from the get-go -- the 100-series was Wang's attempt at making a
calculator that was cheaper than the 700-series calculators that were
Wang's top-end machines, with amazing capabilities and speed. The
100-series was a huge compromise, using a serial bit-by-bit ALU, the
"cheap" diode (slow) ROM versus the (fast) wire-rope ROM of the
700-series, and keycode-encoded programs for advanced math operations
(trig & statistics) versus microcoded routines on the 700-series. By
the time the 100-series machines made it to market, the technology used
in them had been eclipsed by solid-state ROM, and higher-levels of TTL
integration, pretty much making them dead-ends. They never sold well,
and planned improvements, like an external learn-mode programmer and
other peripherals were canceled.
I got it years ago, and used the keyboard, case, and PSU as part of my
homebrew machine. I think i have the main PCBs mostly
I did desolder some of the connectors and maybe the odd IC, though.
A worthy use for the parts at the time. No faulting you for building a
homebrew machine from it.
IIRC there were 3 boards in the pile. The bottom 2 were the diode
firmware ROMs, the top one was full of mostly TTL.
That's the one. The top board had almost all the logic, and the two
bottom boards had the diode ROM matrices.
The top board had a mix of TTL and DTL ICs on it, mostly small-scale.
There was another 24 pin
IC (the ROM you mention) and some RAMs (1101a?).
The 24-pin IC was part of the microcode sequencer, a mask-programmed TMS
2600 device. The RAMs were indeed 1101A's, either genuine Intel, or
second-sourced parts from various IC houses. There are four sockets, of
which two are populated for the "base" models with 4 memory registers.
The other two sockets were populated for the "extended" models, which
had 12 memory registers.
I seem to remember a
couple of smaller PCBs tht fitted on top, display drivers?
Yes. The display or printer driver board plugged into a socket on the
main board. In the models with Nixie displays, the BCD- to 1-of-10
chip, and display drive transistors were on this board. On the models
equipped with the built-in printer, the circuitry to drive the printer
(a Seiko drum printer) were on the board. There was a socket on either
of these boards that another board could plug into which was the
Trig/Statistics ROM board. This board contained some sequencing and
addressing logic, along with another mask-programmed TMS 2600 ROM that
contained keycode sequences to carry out (rather slowly) trig and some
statistics functions. This board was an extra-cost option.
for more information.
The Old Calculator Museum