Well, Kai, while I've agreed with you most of the time up until now, I have to differ. While it's true that this smacks of a "legacy" design, and while high-density components such as many people really like, because they have the "special" features, and, while it's true that those high-density components aren't easy to wire-wrap, all my wire-wrap boards have solid power and ground planes with a dry-film solder mask that's easy to remove wherever you want to place a bypass cap. I've had boards of this type made for my own use since before 1980 and, while I stopped selling them in the mid-late '80's, because my favorite board house had shut down due to the cost of environmental compliance, I still use 'em when it suits me. When I run out, I don't know what I'll do. Perhaps I'll have 'em made in China.

I also have to differ with the notion that wire-wrap is unsuited for this sort of circuit. If it were operating at 200 MHz or so, perhaps, though I've shown that's not always the case either. They do tend to radiate at the higher frequencies, though. I've been successfully building wire-wrapped high-speed (>80 MHz) digital circuits since the 'late '70's though, and never had a problem that couldn't be worked out.

Everybody seems to agree that a board such as this is a pretty silly project. Who will buy it? Any controller slow enough to work with an 8255 is too slow to justify a new circuit. Why on earth would anyone want an external interrupt controller for use with a simple-minded chip like this?

If it's for development use, it should leave the internal resources of the MCU avaiable for development, hence, shouldn't use the serial port(s), timers, etc, for support of the tools. That means it needs an external serial channel, baud rate generator, and timebase. It's bad enough that it chews up two of the availble parallel ports for external memory. That's actually another reason the old-style chips with <64KB of internal FLASH and <64KB of internal RAM shouldn't be used in a "new" circuit unless one's sure one will not need the entire range of RAM.

The other thing to keep in mind is that a board with most of these features on board is available and has been for about a decade, in the form of the NMIY-0031 board costing about $30 assembled, tested, and complete with a monitor PROM. It's not alone.

RE