4 variations, if I remember correcly. And they are pretty clearly described both in the PDF manual and in the help in MPLAB. UDATA : "normal" banked GPRs ("DATABANK" in the LKR). UDATA_SHR : "unbanked" GPRs ("SHAREBANK" in the LKR). UDATA_OVR : overlayed (reused between modules) GPRs. UDATA_ACS : GPRs from the access bank (on PIC18's). Jan-Erik. M Wedin wrote: > There are quite a few variations of udata. Together they clear up very > little of my confusion. I'll hack some code and see if brute experience w= ill > help. > = > Men tack f=F6r hj=E4lpen! > = > Wed > = > = > 2007/10/8, Jan-Erik Soderholm : >> M Wedin wrote: >> >>> I would guess it is because the GP registers I define are shared over >> the >>> banks. But I think it ought to cover the two banks of the F84 as well. >> The >>> F87xa datasheet says nothing about it though. >> Yes, since F84(A) also has *only* "shared mempory" one could >> guess then one should use UDATA_SHR... >> >> BUT! Since Microchip has selected to call the section >> in the LKR file for "DATABANK" in the 16F84.LKR and for >> "SHAREBANK" in the 16F874.LKR, you have to use UDATA >> for the 84(A) and UDATA_SHR for the 874A. *OR* edit >> the LKR files, if you prefer that. That's perfectly >> OK, they are only "sample linker files" anyway... :-) >> >> UDATA allocates GPR's from "DATABANKs". >> UDATA_SHR allocates GPR's from "SHAREBANKs". >> >> I guess one can blame this on the amount of time that has >> gone between the introductions of the 84A and the 874A... >> >> >>> I would be more than happy >>> to be pointed to some good reading on the subject. >> The MPASM/MPLINK User Guide. >> >>> Right now I am going throug 33014g.pdf >>> from Microchip. If there are better descriptions,... >> Hm, 33014h.pdf maybe ? :-) :-) >> >> Jan-Erik. >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist