32016 Second Processor
A second processor for the BBC/Master or Acorn Cambridge Workstation containing a National Semiconductor 32016. The "cheese wedge" second processor contains 1M of RAM and was marketed as the Cambridge CoProcessor. The Acorn Cambridge Workstation contained a 32016 CoProcessor with 4M of RAM.
The 32016 client MOS is called Pandora and provides the basic system required to communicate with the host computer. Disk-based software provides an operating system called Panos, very similar to Unix in appearance. Panos also has a lot of internal similarities with ARM Arthur and shows Arthur's programming heritage.
ROM images and system disks for the 32016 CoProcessor are available at mdfs.net and elsewhere.
MOS API Calls
Programs communicate with the kernal and MOS via the SVC Supervisor Call opcode. Parameters are passed in registers R1 onwards. Register R0 is not used by API calls other than OS_INDIR.
On entry, R0-R7 contain values to pass to SVC call
On exit, R0-R7 contain returned data
F=0 - no error occured
F=1 - error occured, R1=error number
SVC &00 - OS_INDIR
On entry: On exit: R0=SVC number R1-R7=as called SVC R1-R7=as called SVC
SVC &01 - OS_WRCH
On entry: On exit: R1=character R1=preserved
SVC &02 - OS_STRING - Print String
On entry: On exit R1=>text R1=preserved R2=length R2=preserved
SVC &03 - OS_ASCI
On entry: On exit: R1=character R1=preserved
SVC &04 - OS_NEWL
SVC &05 - OS_RDCH
On entry: On exit:
R1=character
Cy=carry flag
SVC &06 - OS_BYTE
On entry: On exit:
R1=function R1=preserved
R2=first parameter R2=returned word
R3=second parameter R3=returned word DIV 256
Cy=returned carry flag
SVC &07 - OS_WORD
On entry: On exit: R1=function Control block updated R2=>control block
SVC &08 - OS_CLI
On entry: R1=>command string R2=max string length
SVC &09 - UNUSED
SVC &0A - OS_FILE
On entry: On exit: R1=function R1=result R2=>filename R2=undefined R3=max name length R3=undefined R4=load R4=load R5=exec R5=exec R6=length/start R6=length R7=attrs/end R7=attrs
SVC &0B - OS_FIND
On entry: On exit: R1=function R1=handle R2=>string or handle R3=max string length
SVC &0C - OS_ARGS
On entry: On exit: R1=function R1=result R2=handle R2=preserved R3=data R3=data
SVC &0D - OS_BGET
On entry: On exit:
R1=byte
R2=handle Cy=carry flag
SVC &0E - OS_BPUT
On entry: On exit: R1=byte R1=preserved R2=handle R2=preserved
SVC &0F - OS_GBPB
On entry: On exit:
R1=function R1=result
R2=channel R2=channel
R3=address R3=address
R4=number R4=number
R5=pointer R5=pointer
Cy=carry flag
SVC &10 - UNUSED
SVC &11 - OS_EXIT
SVC &12 - OS_DEBUG
SVC &13 - UNUSED
SVC &14 - OS_ESCAPE - Read Escape flag
On exit:
F flag=1 - Escape state set
SVC &15 - OS_INLINE - Print inline text
The SVC &15 opcode is followed by a single length byte and the string to be printed.
SVC &16 to &1D - UNUSED
SVC &1E - OS_HANDLER - Set event handler
On entry: On exit: R1=event number R1=preserved R2=offset/module R2=preserved procedure descriptor
SVC &1F - OS_ERROR - Read last error
On entry: On exit:
R1=>buffer R1=preserved
R2=max size of buffer R2=length of error
R3=error number
SVC &20 - OS_SVR - Enter supervisor mode
SVC &21 - OS_ABORT - Jump through ABORT vector
SVC &22 to &27 - UNUSED
SVC &28 - OS_SETVDT - Set Virtual Dispatch Table address
On entry: On exit: R1=new VDT address R1=preserved
SVC &29 to &31 - UNUSED
SVC &32 - OS_SPLIT
SVC &33 - OS_ENTRY - Set Control Program Entry
On entry: On exit: R1=Entry address R1=preserved
SVC &34 - OS_VERSION - Get version
On entry: On exit: no parameters R1=version*256, eg &200 for 2.00
SVC &35 - OS_SETVDU - Set VDU handler
On entry: On exit: R1<256 - Handler ID R1=previous handler R1>255 - =>handler
SVC &36 (54) - OS_CONFIG - Read config setting
On entry: On exit:
no parameters R1.b0=FPU present
R1.b1=MMU present
SVC &37 (55) - OS_PRIV - Enable/Disable Pandora SVCs
On entry: On exit: R1=SVC call number R1=preserved R2.b0=0 - This SVC passed on to VDT R2=previous state R2.b0=1 - This SVC performed by Kernel
SVC &38 (56) - OS_NOLOAD - No OSCLI Load
On entry: On exit: R1.b0=0 - disable LOADs from OSCLI R1=previous state R1.b0=1 - enable LOADs from OSCLI
SVC &39 (57) - OS_CONTROL - Enable/Disable event
On entry: On exit R1=event number &FB..&FE R1=preserved R2.b0=0 - disable R2=previous state R2.b0=1 - enable
SVC &3A to &3F - UNUSED
See also
Jgharston 17:30, 12 December 2007 (UTC)
