Difference between revisions of "OSWORD &05"
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− | [[Category:OSWORD]] | + | [[Category:OSWORD]][[Category:Second Processors]]__NOTOC__ |
− | OSWORD &05 (5) - Read I/O processor memory | + | ==OSWORD &05 (5) - Read I/O processor memory (Acorn MOS 1.00 and later)== |
− | Acorn MOS 1. | ||
− | + | 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== | ==Coding== | ||
Line 16: | Line 15: | ||
<code>X%</code>=>5-byte control block, <code>Y%=X%DIV256</code>. | <code>X%</code>=>5-byte control block, <code>Y%=X%DIV256</code>. | ||
− | + | 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 | ||
− | ==See | + | By copying code to the I/O processor and the I/O processor's USERV you can |
+ | call an arbitary address in the I/O processor. | ||
+ | |||
+ | DEFPROCmem_call(io%,A$):LOCAL old% | ||
+ | !X%=&200:REPEAT | ||
+ | A%=5:CALL&FFF1:old%=256*X%?4+old%DIV256 | ||
+ | A%=6:X%?4=io%:CALL&FFF1:io%=io%DIV256 | ||
+ | ?X%=?X%+1 | ||
+ | UNTIL ?X%=2 | ||
+ | OSCLI "LINE "+A$ | ||
+ | !X%=&200:REPEAT | ||
+ | X%?4=old%:CALL&FFF1:old%=old%DIV256 | ||
+ | ?X%=?X%+1 | ||
+ | UNTIL ?X%=2 | ||
+ | =B% | ||
+ | : | ||
+ | DEFFNmem_call(io%,B%,C%):LOCAL old% | ||
+ | !X%=&200:REPEAT | ||
+ | A%=5:CALL&FFF1:old%=256*X%?4+old%DIV256 | ||
+ | A%=6:X%?4=io%:CALL&FFF1:io%=io%DIV256 | ||
+ | ?X%=?X%+1 | ||
+ | UNTIL ?X%=2 | ||
+ | B%=FNbyte(136,B%,C%) | ||
+ | !X%=&200:REPEAT | ||
+ | X%?4=old%:CALL&FFF1:old%=old%DIV256 | ||
+ | ?X%=?X%+1 | ||
+ | UNTIL ?X%=2 | ||
+ | =B% | ||
+ | DEFFNbyte(A%,X%,Y%)=((USR&FFF4)AND&FF00)DIV256 | ||
+ | |||
+ | <code>PROCmem_call(address,"string")</code> will call ''address'', entering | ||
+ | with A=0 and XY pointing to ''string''. For example, | ||
+ | <code>PROCmem_call(&FFF7,"HELP")</code> calls OSCLI in the I/O processor. | ||
+ | |||
+ | <code>result=FNmem_call(address,param1,param2)</code> will call ''address'', | ||
+ | entering with A=1, X=param1 and Y=param2, and will return the result in XY. | ||
+ | For example, <code>result=FNmem_call(&FFE7,0,0)</code> will call OSNEWL in | ||
+ | the I/O processor. | ||
+ | |||
+ | You should be careful if the called code generate an error as then USERV | ||
+ | will not be restored to its previous value. | ||
+ | |||
+ | ==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. It is possible to | ||
+ | write a modified Tube Host that intercepts OSWORD 5 and 6 to access extended | ||
+ | memory, but most programs rely on adding an extra OSWORD call. | ||
+ | |||
+ | ==See also== | ||
* [[OSWORD &06]] | * [[OSWORD &06]] | ||
+ | * [[OSWORD &FA]] | ||
+ | * [[OSWORD &FF]] | ||
* http://mdfs.net/Docs/Comp/BBC/Oswords | * http://mdfs.net/Docs/Comp/BBC/Oswords | ||
* MemIO library at http://mdfs.net/blib | * MemIO library at http://mdfs.net/blib | ||
+ | ---- | ||
[[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) | ||
+ | [[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 14:01, 31 January 2016 (UTC) |
Revision as of 20:30, 22 January 2021
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
By copying code to the I/O processor and the I/O processor's USERV you can call an arbitary address in the I/O processor.
DEFPROCmem_call(io%,A$):LOCAL old% !X%=&200:REPEAT A%=5:CALL&FFF1:old%=256*X%?4+old%DIV256 A%=6:X%?4=io%:CALL&FFF1:io%=io%DIV256 ?X%=?X%+1 UNTIL ?X%=2 OSCLI "LINE "+A$ !X%=&200:REPEAT X%?4=old%:CALL&FFF1:old%=old%DIV256 ?X%=?X%+1 UNTIL ?X%=2 =B% : DEFFNmem_call(io%,B%,C%):LOCAL old% !X%=&200:REPEAT A%=5:CALL&FFF1:old%=256*X%?4+old%DIV256 A%=6:X%?4=io%:CALL&FFF1:io%=io%DIV256 ?X%=?X%+1 UNTIL ?X%=2 B%=FNbyte(136,B%,C%) !X%=&200:REPEAT X%?4=old%:CALL&FFF1:old%=old%DIV256 ?X%=?X%+1 UNTIL ?X%=2 =B% DEFFNbyte(A%,X%,Y%)=((USR&FFF4)AND&FF00)DIV256
PROCmem_call(address,"string")
will call address, entering
with A=0 and XY pointing to string. For example,
PROCmem_call(&FFF7,"HELP")
calls OSCLI in the I/O processor.
result=FNmem_call(address,param1,param2)
will call address,
entering with A=1, X=param1 and Y=param2, and will return the result in XY.
For example, result=FNmem_call(&FFE7,0,0)
will call OSNEWL in
the I/O processor.
You should be careful if the called code generate an error as then USERV will not be restored to its previous value.
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. It is possible to write a modified Tube Host that intercepts OSWORD 5 and 6 to access extended memory, but most programs rely on adding an extra OSWORD call.
See also
- OSWORD &06
- OSWORD &FA
- OSWORD &FF
- 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) Jgharston (talk) 14:01, 31 January 2016 (UTC)