Apple-2-SW/prog8
1
0
Fork 0
mirror of https://github.com/irmen/prog8.git synced 2024-12-24 01:29:28 +00:00
Code Issues Projects Releases Wiki Activity

attempt to clarify docs of cx16.numbanks()

Browse Source
This commit is contained in:
Irmen de Jong 2023-02-13 23:45:01 +01:00
parent 9e0f8c1a97
commit 3916de2921
2 changed files with 8 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
compiler/res/prog8lib/cx16/syslib.p8
View File

@ -454,20 +454,19 @@ inline asmsub getrombank() -> ubyte @A {
}
inline asmsub getrambank() -> ubyte @A {
; -- get the current ram bank
; -- get the current RAM bank
%asm {{
lda $00
}}
}
asmsub numbanks() -> uword @AY {
; -- uses MEMTOP's cx16 extension to query the number of available RAM banks. (each is 8 Kb)
; Note that the number of such banks can be bigger than 255 so a word is returned, but mostly
; the A register could suffice as the lsb.
; The maximum number of banks is 256 = 2 Megabytes of banked Ram aka Hiram. (Y=1 and A=0 in this case).
; MEMTOP itself reports 0 in this case which we change into 256 for convenience.
; It reporting 0 doesn't mean 'zero banks', instead it means 256 banks (=2Mb banked RAM),
; as there is no X16 without at least 1 page of banked RAM.
; -- Returns the number of available RAM banks according to the kernal (each bank is 8 Kb).
; Note that the number of such banks can be 256 so a word is returned.
; But just looking at the A register (the LSB of the result word) could suffice if you know that A=0 means 256 banks:
; The maximum number of RAM banks in the X16 is currently 256 (2 Megabytes of banked RAM).
; Kernal's MEMTOP routine reports 0 in this case but that doesn't mean 'zero banks', instead it means 256 banks,
; as there is no X16 without at least 1 page of banked RAM. So this routine returns 256 instead of 0.
%asm {{
phx
sec

2
compiler/res/version.txt
View File

@ -1 +1 @@
8.9
8.10-dev