4K HP 67 Games rom attached for testing

[Gene]

(11-02-2016 09:33 PM)Dieter Wrote:  I'm asking because I found something that might be an error or not. Take a look at the LBL 00 routine starting at line 107. A counter in R05 is set to zero and then increased if the input matches R20, ... R23. This is done with an ISG command followed by CLX, but these CLXes are never executed as they will always be skipped. So the program compares R20 with R21, R21 with R22, ... etc. Is this how it is supposed to work? After looking at the original Games Pac code (page L06-02) I'm still not sure. For me it looks like the original '67 program also has an error here.

Gene: At a first glance, it does not appear to be the same. In the original, LBL 1 recalls 10 and adds it to memory 5. Robert's port adds 1 to memory 5 for a alglog detection using ISG and after the scan, multiplies the total by 10. That is fine, but the CLX is always skipped by the ISG (problem because we don't have an INCrement instruction.

A fix is to change the instruction after the ISG 05 to a true NOP and then the CLX. That will add 4 ? bytes, but that's ok we have them to spare.