Second (partial) attempt at a a 2-color bitmap image on a C64 as a collection of characters (8-by-8 pixels tiles, still only 39). This is very laborious—if done by hand. I had to change the original rather drastically, and reuse tiles with care. There’s still a good resemblance, of course. 👨‍💻

I wonder if it’s possible to render this as 8 by 8 tiles, and if so, how to do it. 👨‍💻

As expected, Apple Journal didn’t click with me. It seems I’m not a journaler, and started to get annoyed by the similar suggestions. So, no DayOne subscription for me either.

I made start with software sprites using programmable characters on a Commodore 64. For now, there are just programmable characters; there’s no background, nor a software sprite that should move over the background in one of the 1000 possible positions on a 25 rows by 40 columns text screen.

I drew something loosely based on a picture I took of my sister on Christmas day while we visited the royal palace Het Loo in the east of the Netherlands (I live in the west).

Here’s the process video in ibisPaint X (90 minutes drawing time).

While in the previous article I was only philosophizing, in this one, I’m getting somewhat less theoretical. It’s still a ways away from having working code, though. I found an answer on the Retrocomputing Stackexchange site, explaining how software sprites “work”. In my own … read more

Visited Palace Het Loo yesterday. Just in case, I reminded myself of the Sphinx riddle here. I didn’t take much pictures of this former royal residence, now museum, because I was after good impressions, not documentation. I was sightseeing, after all. Made me a little more pro house of Orange. 🇳🇱

My iPad is having issues. I already have powered down and up again twice this week because of lack of responsiveness. I suppose it could be that the CPU is being slowed down to compensate for an elderly battery, or whatever goes on in the proprietary iPadOS from Apple 🤷‍♂️ Who knows, who knows…

While reading through some articles about hardware sprites, sometimes called movable object blocks (MOBs), I realized that the C64 is probably too slow to move software driven sprites. In 1/60 s at ± 1.02 Mhz there are 17000 instruction cycles for an interrupt, or (17000 / 4 =) 4250 average … read more

I have a very unoptimized way to fill a rectangle on a C64 video screen with characters, as in a MOB (movable object) instead of a hardware sprite. It’s around 25 times faster than using Basic, and has “frame rate” of around 12 fps on a 50 Hz monitor. I’m sure it can be much faster. 👨‍💻

I was looking through the Commodore 64 Programmer’s Reference Guide, in the chapter about graphics, how I could POKE screen codes to the screen, so to speak, in 6502 assembly. Here is what I came up with. First of all, what do I mean with “POKE” and “screen codes”? POKE … read more

On the C64, using the Kernal, you can set the cursor position (one routine) and then print a character (another routine). I wanted a single routine to put a screen code onto the screen, at a particular colomn and row, wherever the screen was located in memory. So I wrote it, and it works, yay! 👨‍💻

I installed droid64, a Java application to manipulate Commodore disk images and copy files between your host OS and a disk image (e.g. a file with a D64 extension). I needed it to be able to play new games. I also put a SPEEDLINK SL-650212-BKRD Competition PRO USB joystick on my Amazon wish list 🎮

It is said, by some, that there’s nothing magical about January 1. So resolutions seem rather nonsensical, at least, putting a start date on something. Just start, which is what I just did, by writing and publishing this blog post. And, I warn you in advance, I will ramble and meander through … read more

I redid the random maze program in assembly language. If you load and RUN the program, it displays the maze, waits for the user to press a key, then clears the screen and returns to the BASIC prompt. It’s simple, but it made me proud nonetheless that it actually works.

Two very eager feline buddies 🥰

I have found a better way to assemble 6502 code than Virtual 6502 Assembler. I installed DASM from the official Pi OS repository on my Raspberry Pi-400, rewrote the KickAss source code, and assembled that into a BASIC loader program. Took long, because of differing assembler directives, and a nasty typo 🤬

The file I assembled and downloaded as a .PRG file, using the Virtual 6502 Assembler, I smart attached in the V.I.C.E. C128 emulator. I then attached an empty .D64 disk file, and used Basic 7.0 to save memory location $C000 to $C12F to a binary file, called “usrfunc04.c000”. I detached … read more

I had to search for a particular Commodore 128 command, and found it here, which, BTW, I typed in myself from a book, and corrected many errors in that book. It now is the definitive guide on the web for Commodore 128 retro-computer users. It is anonymous, though, since I haven’t written the book.

In the Commodore 64 Programmer’s Reference Guide, published by Commodore Business Machines, Inc. and Howard W. Sams & Co., Inc. in 1982, there is a chapter on programming graphics with history’s most popular retro-computer. Graphics are an essential part of computing, and … read more