There are a confusing set of ARM development ROMs. I'm not sure what the exact difference between different versions is. Eval099.rom Executive version 1.00 (6th June 1986) Acorn ARM Second Processor Supervisor 1.00 ARMJUN86 Executive version 1.00 (6th June 1986) Acorn ARM Second Processor Supervisor 1.00 Eval100.rom Executive version 1.00 (6th June 1986) Acorn ARM Second Processor Supervisor 1.00 SWIs up to &1B (no OS_Mouse) Checks for *Help, *Go, *Close as words *MemoryI Brazil005.zip Brazil version -.005 (8th August 1986) Acorn ARM Second Processor Brazil Supervisor 1.00 ARMAUG86 Brazil version -.005 (8th August 1986) Acorn ARM Second Processor Brazil Supervisor 1.00 Eval101.rom Executive version 1.00 (14th August 1986) ARM Second Processor Supervisor 1.00 Chris's version 19/11/87 SWIs up to &1C, adds OS_Mouse Checks for *Help, *Go, *Close initial letters Checks Break type at reset instead of ResetAck *Dis *Cache, *UnCache Copied from live system at 1995 Acorn Show Spring130.rom Acorn SpringBoard 1MByte Executive. Version 1.30 25th June 1987. Assembly options used: A5002P ADEV IOC MEMC VIDC The Acorn RISC SpringBoard - Version 1.30 25th June 1987 Supervisor BrazilM4.zip Brazil a500dev io DUAL memc version -.005 (18th November 1987) Acorn RISC Second Processor Brazil Supervisor 1.00 Copied from ABUG A500 Domesday development system Environment string at &E00 &0E40: abort register store &0E00: error buffer Internal commands appear to only be checked from Supervisor prompt