I’ve implemented the new memory map I described earlier, updated the software, and everything’s working great. This has allowed me to finally make some progress on my goal of a menu-driven bootloader, with a catalog of built-in demo programs from the expanded ROM space. Here’s a screenshot of an early version of the new bootloader, with a couple of demos installed:

On the whole, it works great, and I’m very happy with it. After selecting a built-in demo option, the selected program starts in about a second. Next, I’d like to expand on the bootloader menu concept a bit further.

• Add a power-up sound, along the lines of the Amiga or Mac.
• Design a better logo.
• Dress up the boot screen with some more interesting graphics– a spinning box maybe? That’s an awful lot of plain text up there, and is kind of intimidating. Maybe you should have to press F8 to reveal “advanced boot options” like Windows.
• Create a good video demo. Microchess is the only program that shows anything halfway-interesting graphically.

Not unexpectedly, there are also a pile of small problems to work through:

• With the new bootloader, when BMOW has been turned off for several hours, it almost always crashes on bootup while drawing the BMOW logo. If I press the reset switch, it crashes again. After four or five resets, it works OK, and continues to work until the next lengthy shutdown. Sounds like the program is relying on uninitialized memory somewhere.
• About one time in ten, it will crash while downloading a new program image with the bootloader. I think this is related to a feature I added to show the percent complete on the LCD during download.
• All the demos I want to include won’t fit in 128K. The audio demo alone is 64K. I need to implement some kind of uncompression routine to extract compressed demos from ROM.
• After booting a demo program, the first keypress will not be recognized. After that, keyboard input works fine.
• There’s major video noise when navigating the boot menu. I need to delay the screen updates until the VBLANK period.