BRADLEY'S BASIC
Pokes.
This is a new project that finds its origins in code I was writing between 1983 and 1987. The original project was un-originally named DESMOND'S BASIC - an ongoing project to add various capabilities to BASIC2.0 which I started pretty much as soon as I got my C64.
There's a legendary fellow in the Toronto Commodore community named David Bradley and I've created this little project for and in honour of him.
David has a YouTube channel where he tinkers with his collection of Commodore equipment he's amassed over the years. It's great to let David do his thing in the corner of the screen while you're doing yours. You'll even learn something - I have and I clearly know everything. Take a look at his YouTube channel here: https://www.youtube.com/@DRBradleyPhotography
Whenever David powers on a C64 to test it or a 1541 he'll invariably tap in the incantation:
POKE 53280,0
POKE 53281,0
CTRL-2
He does this so we can all read whatever is on the screen. And he does it EVERY TIME. And it bugs me. And thus I must interfere, um intervene.
David does it more efficiently than this.
A black and white solution
Creating custom ROM images is fun and easy and we'll get David his white text on black screen in no time!
Changing the kernal ROM to switch the colours requires changing 3 bytes: one for the border colour, one for the screen colour and one for the text colour.
So I modified a kernal ROM, programmed a 2764 EPROM and stuffed it into a DIP adapter that I had spare.
Problem solved!
David can now boot into a white-on-black display any time and every time!
... if he opens up the machine first and replaces the kernal ROM with my EPROM.
... if the kernal ROM isn't soldered in.
... if he's using a machine that has separate kernal and BASIC ROMs.
That's better
A bit better, a bit worse
Ok, so how about a cartridge? A cartridge will work on any and all C64s and even a '128.
The simplest implementation is an 8K ROM located at address $8000. The trade-off for this is 8K less memory for BASIC. That's quite a reduction in memory just to change the colour of the screen.
David often tinkers with 1541s and explores the contents of his myriad disks. How about I put the BASIC4.0/7.0 disk commands in the cartridge too? I already have the code after all. Cool. It's a plan.
While I was at it (and delaying writing documentation) I added a DOS-Wedge (new code) in the cartridge too plus a couple of extras. And the Bradley's BASIC cartridge V1.0 is complete. I also made a disk-loadable version so even people that don't mess with hardware or have an EPROM programmer can pretend they're David too. You can fetch your copy here: Bradley's BASIC Downloads. I've even provided a version with a slightly less stark colour-scheme.
Who types out directory in full?
And next?
There's still a fair amount of space left in the 8K ROM and it's just begging to be filled up.
There's a couple of BASIC4.0/7.0 commands I didn't implement yet (DOPEN, DCLOSE etc) so I should do that at some point. Plus I have some ideas to slim-the code a little.
But what else? Direct support for CMD/SD2IEC style directories perhaps? A monitor would be cool too. What do you think?
Overkill for an 8K /EXROM cartridge