VirtualRPC-DL

Does anyone know if the 4.02 ROM file can be replaced with VirtualRPC-DL – without having to softload the replacement ROM?

ie be made to behave like RedSq – and be able to use various ROxx.

Yes, it is possible. You can soft link “ROM” to the actual rom and “hostfs” to the actual directory.

The question is :- what format is the original ROM 4.02 in?

With ref to VirtualRPC-DL – what does the ref to ‘ARM7’ model mean?
Are some of the ARM instruction missing – compared to SArm?

With ref to VirtualRPC-DL – what does the ref to ‘ARM7’ model mean?

ARM7, if I recall, was the RPC module that was a small improvement on the ARM6 originally fitted. ARMv3 instruction set I believe.
Not in the same league as the SA, but would probably run donkeys years old software that breaks on SA.

I was thinking more on the lines of RO5 and Otter running on VirtualRPC-DL.

I was thinking more on the lines of RO5 and Otter running on VirtualRPC-DL

On first seeing the info for VRPC-DL I did wonder about the fiddles (hacks?) required to run RO5 on it.

A few modules need updating like in RSqrl – should be a fair bit faster!
Interesting from Usernet – VRPC-DL running RO6 – still uses its resolver module and not RO6 version.
(anyone using RO5 ‘Otter’ can they use Google Groups?)

A few modules need updating like in RSqrl – should be a fair bit faster!

Sounds like you’ve run the test setup.

Did a old version of OS_EnterOS (Arthur/RO2) disable the interupts?

Is there a list of the ARM instructions which the StrongArm implemented?
(so to make a test program – to find out which ARM instruction may or may not have been implemented in a Emulator)

Does RO six have swi “OS_LeaveOS” implemented?

Does this bit of code mean anything?

teqp pc,#0
teqp pc,#0
nop
******

Did a old version of OS_EnterOS (Arthur/RO2) disable the interupts?

No. It just returned from the SWI handler, with SVC mode intact.

From RISC OS 2:

; The SWI Despatch routine

SVC * {PC}-SWIRelocation

        Push    "r10-r12"

        BIC     r12, r14, #ARM_CC_Mask
        LDR     r11, [r12, #-4]
        BIC     r11, r11, #&FF000000
        Push    r11
        BICS    r11, r11, #Auto_Error_SWI_bit
        BEQ     SWIWriteC + SWIRelocation

        ORR     r10, r14, #SVC_mode
        TEQP    r10, #0                 ; restore caller's IRQ state

        CMP     r11, #OS_BreakPt
        CMPNE   r11, #OS_CallAVector
        BICNE   r14, r14, #V_bit        ; clear V unless BreakPoint/CallVector

        CMP     r11, #OS_WriteI
        LDRCC   pc, [pc, r11, LSL #2]

...

        & SENTERSWI

...

SENTERSWI ORR   lr, lr, #SVC_mode
        ExitSWIHandler

If you are disassembling, the IntOn and IntOff code is just above SENTERSWI, which may be why you might have thought this?

Is there a list of the ARM instructions which the StrongArm implemented?

Possibly. I’m not having much luck finding anything due to the age and the wild popularity of the ARM family. ARM710 was ARMv3 while SA110 was ARMv4. I recall (U)MULL was new to StrongARM, though I’m not sure what others there are. It was the first of the split-cache ARMs, and it had an oddity that PC pointed, I think, three instructions beyond the current (rather than the usual 2). Re. OS_PlatformFeatures 0 bit 3.

(so to make a test program – to find out which ARM instruction may or may not have been implemented in a Emulator)

Set an abort handler and just test ’em all?

Does RO six have swi “OS_LeaveOS” implemented?

I have not found any documentation to state that it does, however if it can run a later version of the CallASWI module, it will be provided by that.

Does this bit of code mean anything?
teqp pc,#0
teqp pc,#0
nop

My memory of the 26 bit mode stuff is rusty these days, however I would have imagined that TEQPing zero into PC would zap all the flags – NZCV unset, FIQ/IRQ enabled, USR mode.
Not sure why the instruction is repeated, though.

Thanks for the help – is it possible to catch a undefined instruction and replicate it?

Also is there a wimp prog that would press a function key – say many of thousands of times?
ie a box ^1000000 showing the number of key presses required.
For getting a debug prog running – and go away and let it do its own thing – till an error is raised.

Thanks for the help – is it possible to catch a undefined instruction and replicate it?

Yes. That’s how FPE works. Practically none of the RISC OS machines were fitted with a real FPA, so a clever module traps the undefined instruction abort, checks if it is an FPA instruction (CP1 or CP2), and if so goes and fakes the operation.
Something similar could provide SWP on later ARM devices.

Also is there a wimp prog that would press a function key – say many of thousands of times?

Write a dummy application to start up, poll, and call…what is it? Wimp_ProcessKey? I’m writing this on my phone in bed, but there’s a Wimp SWI used to pass on global keypresses like F12. Thing is, you can (ab)use it to stuff all sorts of keypresses into the system. Many years ago I wrote an app that would “type” the contents of a text file to applications that didn’t directly accept files.

Bake in a secret keypress, like holding both Alt keys, to get the program to stop and quit. Because things can be difficult if you’re trying to quit an app that is firing off loads of fake keypresses. Yeah, this is the voice of experience. ;-)

Does anyone here really understand the FPE module – I would have thought a new module for the Hardware Floating point would have been very useful.

Unless the ‘C’ compiler comes up with a way of producing code that could handle both – something like the catching of 26/32bit code.
So that one version of the prog/code could be produced – instead of multiple versions for each set of hardware.

Is there an example of a module catching a undefined instruction out there?
(Seems to ring a bell – from the past RiscUser)
Thats if SWP’s number hasn’t been reused :-(

I was thinking of the Long multiply – for the VirtualRPC-DL – but it is possibly – that it may have been implemented.

So no function key prog – thought I’d ask – I wonder if a simple prog could be run in a Task window – producing Function key presses – that could be fed into another window accepting key presses.
I could then simply change the number of key presses!!

Does anyone here really understand the FPE module – I would have thought a new module for the Hardware Floating point would have been very useful.

Jeffrey has written recently in these forums about this. The jist of it as I recall was the overhead of using the hardware is at a level that it would not make a significant difference. He is looking at improving compile time usage with a filter for older hardware. i.e. the same binary would run on all hardware.

Google Finds me an eight page thread:
https://www.riscosopen.org/forum/forums/2/topics/3457?page=1

With VRPC-DL max Screen memory is 8Mb – but without setting Vram to 8Mb – running RO5.23 the screen memory in the task window can be dragged out to 32Mb.
Is there a way for the os to bypass the BandLimit?

Has there been changes – that upset !MakeModes?
(unknown error number 4096)
and then crashes out when generating a MDF (type =2)