Single channel versions of analog switches are available. Surface mount but not crazy small so not much larger than a BJT.

For instance M74VHC1GT66DFT2G and many others https://mou.sr/3KSr3si

This is also described in the Philips document Bi-directional level shifter for I2C-bus and other systems.

Cool, my wife and I did some contract work for Solartron at that office in Farnborough. Power station turbine monitoring using DEC and HP Unix systems for data logging. Nice people. No 6502s in sight unfortunately.

Does the assembler allow the use of '<' or '>' to force the address size? The CA65 assembler uses < and > to select the low byte and the high byte respectively. It uses ^ to select the bank byte.
The address size can be forced using z:, a: and f: as prefixes for 8, 16 and 24 bit addresses.
It's ...

Thanks, that makes it clearer.

Direct page could be anywhere so LDA 0,X is ambiguous unless the assembler has more info. By defaulting to the 16 bit address it won’t be wrong if zeropage was intended but it wll be wrong if direct page was intended AND the page is no longer at $0000. If you are ...

I have ported w65c265sxb-hacker . This produces output which is identical to the WDC Tools version. I am waiting for USPS to deliver my W65C265SXB board to test it.

One oddity that I noticed on both the sxb-hacker ports.

For the following instruction stz 0,x The WDC Tools generated an instruction ...

You can define set USE_FIFO to 1 in w65c816sxb.asm:39. After rebuilding and uploading, the onboard
USB FIFO will be used for the serial interface of the sxb-hacker program instead of the ACIA.

The USB FIFO uses a FT245 and has large send and receive buffers.
It is much faster and more reliable than ...

I have ported the WDC Tools based w65c816sxb-hacker to use the CC65 suite of tools. W65c816sxb-hacker was developed by Andrew Jacobs and is...

A tool for modifying the firmware on your WDC W65C816SXB Development Board

The SXB development board has a 128K Flash ROM that can be updated under ...

The XC3SB LED comes on when XC3SB is low. As this signal is stolen for this hack the LED is has no real use.

Extending the "mod".

The connection for the XC3SB LED is on pin 12 of U10 via R14 and is ideally placed, being near XUSB pin 38, to use as a ~BANK0 LED.
This LED is connected to +5V and ...

On the Rev C. W65C816SXB boards the 8 input NOR gate has been replaced with a 3K resistor (R23) pulling up to 5V. The BANK0 signal is then provided on the XBUS pin 38, replacing XC3SB. This allows/requires any external expansion to pull BANK0 down when it wants to disable the onboard RAM/ROM and ...

I undisseminated it. I left the link to their file.

Attached is my disassembly of the WDC65c816SK WDCMON. I think I decoded the jump table. Perhaps it will help you fill in the gaps.

It seems to me that the 65C02 contains code that is only relevant for the 65C816.

The attached file produces the same bin as the ROM on the W65C816SXB board when ...

The 6502 world turns slowly and in that time the document has moved

Nice! A special thank you for the MacOS binary release.

In the WDC November Newsletter there is talk of FPGA Microcontroller boards. It looks like they have three FPGA boards, Rev A, B and C, which support various processors and peripherals. It also seems that the nitty gritty code and design files require an NDA to be signed by "Commercial Product ...