rehsd

On my 65265 MCU build, I was curious what it would take to get basic speech capabilities. As I researched this, having the 65265 directly generate speech did not seem like the right approach, primarily due to the CPU-intensive nature of speech synthesis. Rather, a dedicated speech synthesis chip was likely a better approach. Doing a cursory search, I found these as potential options: General Instrument / Microchip SP0256 Family (SP0256‑AL2) Texas Instruments LPC Speech Chips

As my W65C265S hardware build is coming along well, I would like to develop an operating system (OS) for it. While I have done miscellaneous 65xxx development over the years, my code has always been a mishmash of routines. The closest I have come to better understanding operating systems is implementing FreeDOS on my 286/386 builds, where I was adding core BIOS routines to support FreeDOS. So, can I hack my way through this and develop and operating system? Time will tell. So

Continuing my W65C265S project series, I am at a nice milestone where I have a second version of a PCB (actually, a pair of PCBs) -- with significantly expanded functionality from my first PCB. For more background on my work on this up to this point, check out rehsdonline.com/post/w65c265s-single-board-computer . My goal in this post is to work through the two PCBs in the rendering below. This post will be updated as I work through the design and build. [February 07, 2026] I

When I first started working with the W65C265SXB board, I was trying to get interrupts to work and was having no luck getting the interrupt service routine (ISR) to run. My setup was a simple momentary switch pulling down P41 (IRQB interrupt) or P64 (negative edge P64 interrupt). As I reviewed the sample LEDP72.asm that was included with the WDC Tools, I found vectors defined at the end of the file. Notice the Shadow_VECTORS section at $7EE0 and the vectors section at $FFE0

As I've been working on my W65C265S single-board-computer (SBC) project (see rehsdonline.com/post/w65c265s-single-board-computer ), one of the greater mysteries is the parallel interface bus (PIB). I've found limited information about the PIB, other than some basics in the '265 data sheet. I'm hopeful to get the PIB implemented in the latest phase of my '265 SBC project. Here, I will collect information that should be helpful in my goal of implementing PIB for a dual-265 SBC

It has been a few years since I have worked with the 6502 and 65816 processors. Most recently, my focus has been learning about FPGAs and developing my own FPGA PCB . Along the way, I designed some retro 286 and 386 systems, dabbled with a variety of microcontrollers, and learned more about PCB design. I thought it might be fun to build a single-board computer (SBC) based on the W65C265S microcontroller from The Western Design Center (WDC). This post will be updated as I wo