A couple of games back in the 1990s utilised the VGA split screen functionality to enable things that were otherwise only possible on more capable machines, like the Amiga. The VGA split screen allowed games such as Jazz Jackrabbit or Pinball Fantasies to display a static status bar at the bottom of the screen, while the rest of the screen was smoothly scrolling in two or more directions. In this video I will show how this is possible, and which VGA registers to program with the appropriate values.
Tag: retrocomputing
Commodore SFD 1001 Repair
Another dead floppy drive has landed on my desk. I was told that “the motor isn’t working”. That can have different causes, but let’s find out what the actual problem is. I never worked on one of these drives before, but they are related to the CBM 8050, a drive that I like very much.
Spin Me Round: Commodore 1541 Repair
We have another dead 1541 floppy disk drive on the bench today. It is an infinitely spinning drive, so it means that somehow the drive is not booting. But what might be the cause…?
Double Trouble: C64 and 1541 Repair
I have two dead Commodore devices here, that a user asked me to repair. A 1541 floppy disk drive and a bread bin C64. The drive’s motor spins indefinitely and the LEDs don’t come on. The C64 has a black screen. So let’s get cracking, and repair both! With the C64 I made a couple of wrong turns, but in the end all turned out well! The 1541 had some other idea in store for me, and turned out to be a bit on the spiritual side…
Pico DRAM Tester
Eric Schlaepfer aka TubeTime has released an open source tester for vintage DRAM ICs. It is based on the fabulous Raspberry Pi Pico 2 microcontroller. It supports even older chips that use -5V and +12V. I ordered PCBs and the components for building the tester, so let’s warm up the soldering iron and build something!
Let’s Code Commodore PET 0x02: Snakes on a PET
In this episode we code a simple game for the PET. It is the classic snake game, where you control a snake that picks up food and grows longer. We learn how to read from the keyboard, and how to limit the speed of the game, as the PET is slow, but not THAT slow.
Commodore C16 From Hell Repair
This is another dead Commodore machine from the pile of machines that eazy brought over at the beginning of the year. This time it is a TED machine: the venerable C16. It is completely dead, shows no signs of life. But this has never stopped us. Probably a dead CPU. How bad can it be, eh?
Let’s Code Commodore PET 0x01: Hello World!
This time around we will start another, probably short lived Let’s Code series. It will center around the Commodore PET, the first personal computer made by Commodore in 1977. Even before the VIC20 and C64. It shares a lot of structural similarities, but also has many peculiarities. It does not have any proper graphics support, so we will do a bit of a fancy text based hello world program, using direct screen memory access. We will use the modern, optimizing C compiler named oscar64.
C64 Repair: Blue Screen
Another C64 was waiting for a repair. This one had a blue screen on startup, but nothing else. Seems like a good sign, at least a bit of code seems to be executing. But boy, this was not a straightforward repair. I think someone messed with this board before, and left some loose ends.
C1531 Datassette Refurb
The Commodore Datassette is a very classic and iconic piece of equipment. It had a couple of variants. Today we have a black C1531 for the Commodore 264 range of computers: C116, C16 and Plus/4. It has some mechanical issues that we will try to fix.