Commander X16

My question is does the latch that stores the ROMB address also go into a high-Z state or does it still present the bank address? BE's only connections are the expansion slots and the 65C02. BE does not affect the ROM bank address latch. It always presents the bank address. I also found your questi...

Howdy and Live Free or Die.
-also in NH

This ignores the MLB status, It wouldn't be safe for atomic RMW instructions. Right. It is better to wait for an opcode fetch cycle (SYNC asserted) I feel a simple addition of a priority encoder with inputs routed to the expander would have been a neater solution Yes, interrupt hardware is as bareb...

Note that while the 65C02 CPU timings are the foundation, some of the expansion port timings will be due to other parts of the design ... specifically for a bus mastering card, you'd need to know the ROM and RAM speeds and the logic family & number of gates between asserting addresses and gener...

I've downloaded the 65C02 datasheet and will give it a read sometime soon You should read it sooner rather than later. X16 expansion slots are bare-metal direct connections to the 65C02. The datasheet is the expansion bus spec, and any DMA controller needs to meet (or exceed) the timing specified i...

I have had a few multi-day outages, the longest being 5 days after <a href="https://en.wikipedia.org/wiki/2011_Halloween_nor%27easter" rel="external nofollow">Snowtober</a> in 2011.  After that I added a gas-powered portable.  Setting it up was a nuisance, but it was better than nothing.  Until the...

YM2151 fans may enjoy Ken Shirriff's latest <a href="http://www.righto.com/2021/11/reverse-engineering-yamaha-dx7.html" rel="external nofollow">blog post</a>, where he describes internal details of its beefy ancestor, the YM21280.  Some may recognize Ken from his frequent appearances on <a href="ht...

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