67 ISZ

[teenix]

Hi all,

Just playing around with the 67 emulator.

Does the ISZ function actually get a chance to skip on zero or is in only good for a counter?

Example: I = 9.999999999 E99 then do ISZ
I doesn't wrap around to 0 on overflow so still equals 9.9999999999 E99 and therefore a skip never executes.

cheers

Tony

[Werner]

9.999999999 E99 + 1 doesn't overflow of course.
Werner

[ijabbott]

Are you ignoring negative values of I?

[teenix]

(07-14-2020 07:46 AM)ijabbott Wrote:  Are you ignoring negative values of I?

I didn't think of that, negative I values used for ISZ can result in I = 0, but seems not positive numbers.

cheers

Tony

[Paul Dale]

I think the 67's ISZ/DSZ also have interesting behaviour for fractional values. From memory skipping if -1 < I < 1.

ISZ/DSZ were not present on the proposed 67+.


Pauli

[Paul Berger (Canada)]

(07-14-2020 12:46 PM)Paul Dale Wrote:  I think the 67's ISZ/DSZ also have interesting behaviour for fractional values. From memory skipping if -1 < I < 1.

ISZ/DSZ were not present on the proposed 67+.


Pauli

The manual states "For test purposes, numbers between but not including -1 and +1 are the same as zero."

Paul.

[teenix]

(07-14-2020 01:48 PM)Paul Berger (Canada) Wrote:  

(07-14-2020 12:46 PM)Paul Dale Wrote:  I think the 67's ISZ/DSZ also have interesting behaviour for fractional values. From memory skipping if -1 < I < 1.

ISZ/DSZ were not present on the proposed 67+.


Pauli

The manual states "For test purposes, numbers between but not including -1 and +1 are the same as zero."

Paul.

Only the integer part of the number is used, so 0.99 or -0.99 = 0

cheers

Tony

[Paul Dale]

Exactly, this is quite different to ISG and DSE.

The 34S supports all flavours of course.


Pauli

[teenix]

(07-15-2020 04:52 AM)Paul Dale Wrote:  Exactly, this is quite different to ISG and DSE.

The 34S supports all flavours of course.


Pauli

I may be missing something but, I wonder why the comparison is between a 5 digit number and a 3 digit number, ie, is 12345 > 123. I would have thought it would seem more logical to have used two 3 digit numbers.

cheers

Tony

[Paul Dale]

The larger range is useful for DSE.
For ISG, it seems less so.


Pauli