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With a Cherry On The Side – Episode Seven (All the Way to Eleven)

Low-Level Interface

Due to the slightly odd (not to mention a little inconvenient) low-level PS/2 keyboard hardware-interface, a little bit of ingenuity may be required: … 618 more words


Equipment! Loot! Mysterious Artifacts!

How do you identify an adventurer? They’re the ones carrying their own weight in weapons, armor, and dungeoneering paraphernalia. Cool equipment and treasures are essential to the CRPG experience. 334 more words


With a Cherry On The Side - Episode Six (the input-capture interrupt fires)

Captures but No Interrupt

After the tribulations of the last few days, I decided to change the program to display the value in the IC3 captured-value register (TIC3) – the last value of the free-running 16-bit hardware cycle-counter when the most recent IC3 pin-event occurred. 731 more words


Retro Challenge update #5

This week I exchanged the Z80 core in my RC2014 Z80 computer emulator, with an MC6809 core. I couldn’t seem to find a decent HD6309 core but, as you probably know from the previous blog posts, the HD6309 will run MC6809 binaries! 1,271 more words


With A Cherry on the Side - Episode Five (interrupts don't happen at the worst possible time)

Following on from the “final solution” plan described in the previous episode, the first step is to try to simulate incoming keyboard-clock interrupts.

This can be done by using a pin of the output-only PORTB on the 68hc11 directly connected back to the input-capture pin concerned, and then to drive that output pin under software control. 555 more words


It's all about the NPCs

I’ve had a good week full of retrocomputing, but that hasn’t really translated into a lot of progress. Mostly, I blame the Revision Demoparty, which took place last weekend and… 382 more words


With A Cherry on the Side - Episode Four (a plan for the nitty-gritty)

The Nitty-Gritty

At the lowest level PS/2 keyboard interface is an active-clocked packetised serial bitstream using open-drain drivers, running at 10KHz-30KHz (frequency depends on keyboard, and can vary somewhat at runtime!). 463 more words