Hi all,

Thanks for the replies, in the end I went with Daryl's cut down SBCOS files, as they where easy to re-target and did what I needed.

Cheers.

Phill.

Hi all,

Is there a simple 6502 monitor available (as source code) that has the following features....

Must be 4K or less.
Must be able to examine and dump memory, not interested in being able to assemble / disassemble.

The target system (Acorn System 5 clone), will be able to supply routines for ...

flag that is if the last instruction was fetched from this address range Funky! Thanks for sharing that. Do we know what's driven by the flipflop -- where Q goes, what it does? A timing thing, perhaps, controlling wait states? Or altering the presence of IO devices in the memory map? In support of ...

Hi, Phill. Yes, that's right -- you've got the idea. SYNC will be asserted while $A9 (the opcode for LDA#) is fetched. It will be deasserted on the following cycle when the $21 is fetched.

Right, good to have it confirmed to be good, that's what I though the data sheet meant, but thought I'd ...

Just want to try and clarify something, on the WD65c02 data sheet it says :

"The OpCode fetch cycle of the microprocessor instruction is indicated with SYNC high. The SYNC output is provided to identify those cycles during which the microprocessor is fetching an OpCode. The SYNC line goes high ...

Sorry for resurrecting a topic that's over a year old....

Did you ever work out what the problem was using the WD65c02 chip in the PET ?

It seems odd that it won't work, as I've used it successfully in a BBC micro and an Acorn Atom which are of similar vintage and use similar LS chips.

But when I ...

Hi,

Does anyone know a re-seller who sells WDC 6502s, 6522s etc in the UK ?

Cheers.

Phill.

You can assemble in the simulator and save an image of the memory, that's what I do.

Yeah I eventually worked out how to do that :)

However as a more perminent solution I converted the code (via a conversion program, written in delphi), to assemble with BeebAsm, as this is what I was using for ...

Hi,

What assembler should I use to build EhBasic if not using the simulator ?

Cheers.

Phill.

but since they have RS232 to USB, that would be redundant and trivial.
They also have SPI to USB, so if your microcontroller or home-made computer has SPI, you can get USB with one IC. There are probably more of these and cheaper too, since SPI is a better match speedwise than RS-232 is.

There's ...

I'm sure you mean SHIFT the bit

Phill.

Hi people,

Browsing around this site (and the projects linked off it), I have seen two ways of generating Intel like /RD and /WR strobes the most common seems to consist of 3 NAND gates that generate /RD and /WR such that

/RD = R/W NAND PHI2
/WR = (NOT R/W) NAND PHI2

I have also seen a circuit ...