BBC basic assembler and tube

[wemb]

So - probably something obvious I'm misunderstanding..

I've added a PiTubeDirect to my BBC master - and it's great. But I understood that when this is setup, the applications, such as the BBC interpreter will run on the co-processor, but the built-in CPU from the master is used to do I/O tasks. This makes a lot of sense with the behaviour of different Tube CPUs. e..g the 6502 co-processors and their derivatives all run the Basic interpreter, but the z80 one, for instance, does not.

However, but confused about what happens with the BBC Basic built-in assembler. The master's native cpu, the 65SC12 - has some opcodes that the 6502 does not. E.g. BRA

When a write a small program that skips over a call to OSASCI using a BRA to jump over it, it works as expected - but with the PiTube set to emulator 6502 - the same code also works in the same way - the BRA instruction is honoured. What's going on here? The BASIC appears to be running on the co-processor, but is the assembled MC running on the Master's native CPU?

Dave

[SKS1]

I've added a PiTubeDirect to my BBC master - and it's great. But I understood that when this is setup, the applications, such as the BBC interpreter will run on the co-processor, but the built-in CPU from the master is used to do I/O tasks. This makes a lot of sense with the behaviour of different Tube CPUs. e..g the 6502 co-processors and their derivatives all run the Basic interpreter, but the z80 one, for instance, does not.

However, but confused about what happens with the BBC Basic built-in assembler. The master's native cpu, the 65SC12 - has some opcodes that the 6502 does not. E.g. BRA

When a write a small program that skips over a call to OSASCI using a BRA to jump over it, it works as expected - but with the PiTube set to emulator 6502 - the same code also works in the same way - the BRA instruction is honoured. What's going on here? The BASIC appears to be running on the co-processor, but is the assembled MC running on the Master's native CPU?

All 6502-based second processors were CMOS.

[lovebug]

the machine code will be running on the 2nd processor

it looks like pitube is emulating the 65c02 if it allows BRA

im just having a look through the source code here https://github.com/hoglet67/PiTubeClien ... 5tubeasm.S

[wemb]

Ah, yes, that's it - I have a feeling the msg on start of the pitube in 65c02 mode (or some of them, there's several varients/speed options) may have just reported '6502' on boot up. That must have thrown me - yeah- looking at the project mage, they're all the 65c02 - my bad. Thanks!

[hoglet]

im just having a look through the source code here https://github.com/hoglet67/PiTubeClien ... 5tubeasm.S

That's the wrong place.

You need to be looking here:
https://github.com/hoglet67/PiTubeDirect

All of the "6502" Co Processors in PiTubeDirect implement the 65C02 (CMOS) instruction set.

Dave

[lovebug]

That's the wrong place.
You need to be looking here:
https://github.com/hoglet67/PiTubeDirect
All of the "6502" Co Processors in PiTubeDirect implement the 65C02 (CMOS) instruction set.
Dave

oops brain obviously not awake ! thanks