RE: Bugs in Commodore calculators

From: Bo Zimmerman (
Date: 2002-10-09 16:59:03

Well, Marko, I'm glad you are enjoying your new toys-- those are indeed
amusing bugs.

Regarding the SP9000, have you replaced the PS already, or are you using a
simple transformer?  There's an electronics shop here in town that sells
300W (and higher) 110<->220 step-up/step-down transformers for about $25.00.
I use them with all the Euro-machines that I have not replaced the PS in.  I
can give you (or anyone else here interested) their contact information if
you need it.

- Bo

> -----Original Message-----
> From:
> []On Behalf Of Marko Mäkelä
> Sent: Wednesday, October 09, 2002 3:37 AM
> To:
> Subject: Bugs in Commodore calculators
> Yesterday I finally tested my 110-volt Commodores with a 50 watt
> 220->110 volt transformer: the US*1, the 207, the 202 and the SP9000.
> The 207 is a stripped-down version of the 202.  It doesn't have a brake
> lever for stopping the motor after an operation is completed, and it has
> two digits less precision than the 202 and a smaller and less
> powerful motor.
> It was equipped with a black ribbon, and I didn't try it with a black&red
> ribbon, but I think it should be able to print negative numbers
> in red, just
> like the 202 does.  I found three bugs in these calculators:
> - there is no overflow check (well, I didn't expect that)
> - the "× REPT" key does not add up negative numbers
> - the CLR or CLEAR key for cancelling an entry prints a "-" sign at the
>   right margin if the running total is negative (normally it does not
>   print anything)
> The US*1 has a more amusing bug.  Once it is powered up, typing K ÷ (the
> key labelled "K" and the key labelled with the division operator) will
> start an infinite calculation that is constantly updated on the screen.
> Sometimes, this loop cannot be broken with the C key: the calculator has
> to be switched off.  You can also type a number before typing K ÷.  Then
> the display will show parts of the number together with the sequence.
> I guess that it's somehow trying to divide by zero.  This calculator
> lacks overflow and underflow checks as well.  If I remember correctly,
> the only IC inside this calculator has not been made by Commodore or MOS.
> So, the calculator might be from the early 1970s.  The display has orange
> digits and no lenses like some later LED-based models.
> I didn't play much with the SuperPET, as it was overloading and
> overheating
> the transformer.  According to a power meter, it consumed over 70 watts,
> which is well over the 50 watt rating of the transformer.  The US*1
> consumes about four watts (or five when displaying all 8's), and the 202
> (which has a slightly more powerful motor than the 207) took 51 watts when
> the REPT key was being pressed down and the motor was running constantly.
> 	Marko
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