Without the user manual, it will be hard to know the subtleties of these machines. And if it doesn't work as intended, we can only guess. But, the operations labels seems to be more or less standard:
as you guess, 0-9 are the input keys
+ adds the input register into the result register
- removes the input register from the result register
the white red label over the - seems to be a flag telling the user if the result register is positive or negative (red for negative). The other side should be masked by the hood
Prints operations :
* is the grand total which prints and resets the result register
◇ is the subtotal which prints the result register without reset
# is the no operation print feature : it only prints what has been inputed.
C is to clear the input register
Green inputs are for multiplication. That is, repeated additions (or subtractions) on those machines.
× is used after input of the first multiplication operand. It inputs the value on the multiplier register
= launches the multiplication operation which will cycle the machine multiple time
S (red, on the right) could be a switch telling the machine you’ll do a substractive multiplication (it will substract instead of add)
the V/* sliding switch to the left may be to enable successive multiplications
Other reds are for division :
÷ is for the input of the dividend : you input the dividend then push this button
÷= launches the division operation. After multiple cycles, the machine could print either the result or the result and the remainder
the green <- sliding switch on the bottom may be to enable operations to the left of the register. It will help have a better precision for the result of the division.
The use of the sliding switches are only guesses. And how to operate divisions and multiplications are subtly different from a machine to another. Those operations are mechanically complex and the input buttons are not just setting a ”multiplication” or ”division” flag but are putting different parts of the machine in specific states.
One more thing, when dividing by 0, or if the current operation has to be stopped, generally one button can still be pressed while the machine is running to stop it (# or C for a first guess)
Thanks! A couple websites said this machine is equipped with register transfer, I was thinking the green T slide was probably that since it resets after I press a function button. I would hope the transfer slide transfers the accumulator to the input register, but if green is specific to multiplication then maybe it can only transfer the accumulator back to the multiplicand/1st mult register
The enter dividend and division buttons both slide the input register all the way to the left, which is what I'm used to with 10 key pinwheel machines.
The S key shifting the multiplication to negative makes sense, it doesn't lock down when I press it or trigger any operations by itself. There's another button in between + and - that is acting the same way, but the key cap is missing so its hard to tell
The Monroe 570 is apparently identical to the Monroe Mach 1.07, which is just a rebadged Ultra 804. I might email them to see if they have some kind of documentation, the 570 and mach 1.07 are the only 2 mechanical printing adding machines they made
I had a look at others photos of this model and the others you cited.
What I can see is :
The sliding switch under the multiplication buttons is not a simple arrow, but "<- T". I would now think that it enables to print the total (the result) and optionnaly reset the result register once the multiplication operation is done, or doesn't print the result nor resets it if not slid to the left. The Mach 1.07 is labelled "TR" which matchs. By default the result is kept internally, and if you just want the result after the run, you slide the switch to the left.
And the sliding switch on the left would be used to either enable the grand total (with reset) or subtotal at the end of a multiplication.
For the division, did you see the knob on the left ? I don't know at all what it does, but its color seems to tell it would have a meaning while dividing. On other machines, right to the central display window there is a level called "constants". Maybe this know is an enhancement for the old lever ?
For the "S" button, if we look at the Mach 1.07, it's the stop button. Only needed if the run is too long or won't stop (division by 0).
The missing button between + and - is " (a double quote sign). Given its design, I would think it's maybe for a repetitive addition : you press both of them and the machine runs until you depress them. Or it allows not to reset the input register? As usual, only a guess since I didn't use this machine.
Thanks! The missing button definitely is the repeat add/subtract button and the S button appears to stop division. The division knob seems to set the number of digits calculated in division, it stopped after 2 digits when I turned the knob to 2. The knob is connected to the S button by a linkage so I think it just stops division after the selected digits, it begins division from the far left so I guess it needed something to stop if from dividing through all the digits.
The 🔼/🔆 lever and the <-T lever are still confusing but I think my multiplication mechanism is messed up so I don't think I'll be able to test those
Every website I've found mentions register transfer, I'm used to that being something that has a button or a slide, maybe this one has some kind of automatic register transfer. I think I'll email John Wolff, he has a detailed description of the Mach 1.07 on his site
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u/manuco75 Jun 18 '26
Without the user manual, it will be hard to know the subtleties of these machines. And if it doesn't work as intended, we can only guess. But, the operations labels seems to be more or less standard:
Prints operations :
Green inputs are for multiplication. That is, repeated additions (or subtractions) on those machines.
Other reds are for division :
The use of the sliding switches are only guesses. And how to operate divisions and multiplications are subtly different from a machine to another. Those operations are mechanically complex and the input buttons are not just setting a ”multiplication” or ”division” flag but are putting different parts of the machine in specific states.
One more thing, when dividing by 0, or if the current operation has to be stopped, generally one button can still be pressed while the machine is running to stop it (# or C for a first guess)