67 ISZ
07-14-2020, 06:30 AM
Post: #1
 teenix Senior Member Posts: 1,579 Joined: May 2016
67 ISZ
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
07-14-2020, 06:59 AM
Post: #2
 Werner Senior Member Posts: 696 Joined: Dec 2013
RE: 67 ISZ
9.999999999 E99 + 1 doesn't overflow of course.
Werner
07-14-2020, 07:46 AM
Post: #3
 ijabbott Senior Member Posts: 1,129 Joined: Jul 2015
RE: 67 ISZ
Are you ignoring negative values of I?

— Ian Abbott
07-14-2020, 10:05 AM
Post: #4
 teenix Senior Member Posts: 1,579 Joined: May 2016
RE: 67 ISZ
(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
07-14-2020, 12:46 PM
Post: #5
 Paul Dale Senior Member Posts: 1,752 Joined: Dec 2013
RE: 67 ISZ
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
07-14-2020, 01:48 PM
Post: #6
 Paul Berger (Canada) Senior Member Posts: 533 Joined: Dec 2013
RE: 67 ISZ
(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.
07-15-2020, 12:02 AM
Post: #7
 teenix Senior Member Posts: 1,579 Joined: May 2016
RE: 67 ISZ
(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
07-15-2020, 04:52 AM
Post: #8
 Paul Dale Senior Member Posts: 1,752 Joined: Dec 2013
RE: 67 ISZ
Exactly, this is quite different to ISG and DSE.

The 34S supports all flavours of course.

Pauli
07-15-2020, 08:50 AM
Post: #9
 teenix Senior Member Posts: 1,579 Joined: May 2016
RE: 67 ISZ
(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
07-15-2020, 10:36 AM
Post: #10
 Paul Dale Senior Member Posts: 1,752 Joined: Dec 2013
RE: 67 ISZ
The larger range is useful for DSE.
For ISG, it seems less so.

Pauli
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