Difference between revisions of "OSWORD &05"
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[[Category:OSWORD]] | [[Category:OSWORD]] | ||
OSWORD &05 (5) - Read I/O processor memory | OSWORD &05 (5) - Read I/O processor memory | ||
| − | Acorn MOS 1. | + | Acorn MOS 1.00 and later |
On entry: | On entry: | ||
| Line 8: | Line 8: | ||
XY?4=the byte read | XY?4=the byte read | ||
| − | + | Some systems recognise screen memory at &FFFExxxx and sideways ROMs at &FFrr8000-&FFrrBFFF. | |
| − | |||
==Coding== | ==Coding== | ||
| Line 27: | Line 26: | ||
io%=io%+1:mem%=mem%+1:num%=num%-1 | io%=io%+1:mem%=mem%+1:num%=num%-1 | ||
UNTILnum%<1:ENDPROC | UNTILnum%<1:ENDPROC | ||
| + | |||
| + | REM To read a single byte: | ||
| + | !X%=addr:A%=5:CALL&FFF1:byte=X%?4 | ||
| + | : | ||
| + | REM To write a single byte | ||
| + | X%?4=byte:!X%=addr:A%=6:CALL&FFF1 | ||
| + | |||
| + | ==Implementations== | ||
| + | All 8-bit Acorn systems read from whichever ROM is paged in. All except the | ||
| + | BBC B+ read from main memory. The B+ recognises &FFFExxxx to read from the | ||
| + | shadow screen memory, otherwise it reads from main memory. | ||
==See Also== | ==See Also== | ||
| Line 34: | Line 44: | ||
[[User:Jgharston|Jgharston]] 23:56, 30 October 2011 (UTC) | [[User:Jgharston|Jgharston]] 23:56, 30 October 2011 (UTC) | ||
| + | [[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 04:27, 29 March 2015 (UTC) | ||
Revision as of 05:27, 29 March 2015
OSWORD &05 (5) - Read I/O processor memory Acorn MOS 1.00 and later
On entry: XY!0=address to read from On exit: XY?4=the byte read
Some systems recognise screen memory at &FFFExxxx and sideways ROMs at &FFrr8000-&FFrrBFFF.
Coding
The following routines can be used to copy data to and from I/O memory
regardless of the location of the calling program. It requires
X%=>5-byte control block, Y%=X%DIV256.
DEFPROCmem_rd(io%,mem%,num%)
A%=5:REPEAT
!X%=io%:CALL&FFF1:?mem%=X%?4
io%=io%+1:mem%=mem%+1:num%=num%-1
UNTILnum%<1:ENDPROC
:
DEFPROCmem_wr(io%,mem%,num%)
A%=6:REPEAT
!X%=io%:X%?4=?mem%:CALL&FFF1
io%=io%+1:mem%=mem%+1:num%=num%-1
UNTILnum%<1:ENDPROC
REM To read a single byte:
!X%=addr:A%=5:CALL&FFF1:byte=X%?4
:
REM To write a single byte
X%?4=byte:!X%=addr:A%=6:CALL&FFF1
Implementations
All 8-bit Acorn systems read from whichever ROM is paged in. All except the BBC B+ read from main memory. The B+ recognises &FFFExxxx to read from the shadow screen memory, otherwise it reads from main memory.
See Also
- OSWORD &06
- http://mdfs.net/Docs/Comp/BBC/Oswords
- MemIO library at http://mdfs.net/blib
Jgharston 23:56, 30 October 2011 (UTC) Jgharston (talk) 04:27, 29 March 2015 (UTC)
