Questions tagged [commodore-64]

For questions about the different versions and products of the Commodore 64

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4
votes
1answer
1k views

Is it possible to make VICE load .prg files faster?

When I load a C64 .prg with the Hoxs64 emulator, my .prg loads pretty much instantly. But when I load the same .prg file with VICE (x64 app.prg) it takes quite a while (depends on memory map, but ...
17
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2answers
824 views

How to create a switchless multi-system 2 button Atari joystick?

All systems that use the Atari 9 pin joystick standard make use of the following pins in consistent ways, with each direction and the fire button being connected to the ground pin when pushed. 1 - up ...
2
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1answer
278 views

Is it possible to use the BRK instruction when ROM is banked out?

I used to use the BRK instruction when debugging on the C64. However, when I bank out ROM with... lda #$35 // Bank out kernal and basic sta $01 // $e000-$ffff ...the BRK instruction (...
12
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3answers
2k views

What's a good way to implement this “fade” effect on C64

See the beginning of https://www.youtube.com/watch?v=hmfLBAtGAKk. Here's a screenshot: It basically clears characters pixel by pixel both horizontally and vertically. Use sprites for the pixel by ...
3
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3answers
2k views

Reading both keyboard and joystick with non-KERNAL code on C64

I'm implementing non-KERNAL joystick and keyboard controls for my Commodore 64 game. I used to use the KERNAL SCNKEY routine earlier to read keyboard and it worked well with my joystick port 2 code. ...
8
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3answers
1k views

How to transfer files to C64 emulator quickly

I just discovered the fun of writing small programs (Basic/asm) for an emulated C64 for me. Unfortunately, I cannot get used to the emulated C64 keybord, and would like to write the programs on the ...
7
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3answers
3k views

Recovering old Commodore 5.25" floppy disks

I picked up a Commodore 64 with about 1,500 floppy disks. Many of them are de-magnetised and there is currently only one disk I can run (been through about 100, I can see the files of 2 or 3 disks, ...
10
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3answers
768 views

Commodore VIC-20/64/128/16/Plus 4 floppy disk drive replacement

We all know that floppy disks are getting hard to find, and floppy drives are fragile to begin with (especially Commodore's 1541 drive). I know that several companies and parties have released floppy ...
13
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1answer
2k views

Why does the C64 have the following palette?

The Commodore 64 has the following fixed palette of 16 colours: (Your palette may vary due to tuning of screen, etc.) What was the reason for this selection of colours? Are these colours ...
16
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2answers
5k views

Is the s-video output on the Commodore 64 different from “normal” s-video?

I saw Commodore 64 to modern TV about how to connect the Commodore 64 to a modern TV. I don't understand all the details of the answer, so I wanted to try and ask something specific here. In short, I ...
7
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3answers
2k views

Getting your Commodore VIC-20, 64 or 128 online

Back in the day, of course we used modems ("dial-up modems" in today's parlance) to get our Commodores connected to other systems. These days I know several people have concocted options to get ...
11
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4answers
2k views

Who wrote the MS BASIC on the PET/C64/etc?

I'm wondering if anyone has a document that describes the history of the BASIC interpreters used in the various Commodore 8-bit machines? Ultimately I'm trying to track down how it is that the A% ...
24
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1answer
5k views

Why do all the Speech Synthesizers have that same Voice?

The first time I ever played with software speech synthesis on a microcomputer (not hardware synthesis, like in TI's Speak & Spell) was around 1983, using S.A.M for the Commodore 64. A year later,...
8
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2answers
12k views

Best path to learn C64 assembly [closed]

The amount of tutorials, youtube videos, scanned books on C64 programming is overwhelming. What materials would you recommend -- and, importantly, in what order! -- to build a path to programming my ...
3
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2answers
994 views

How can a C64 interrupt let the KERNAL keep operating?

I am working on a loading screen, and what I wanted was a simple raster trick (just change the border colour on the bottom half of the screen), and also call the KERNAL to load some more data from a ...
7
votes
1answer
498 views

Is there a MIME type for C64 .PRG files?

I'm writing an emulator with an HTTP API that could usefully accept C64 .PRG files as the request body of a POST request. This means it has to be able to detect such files by their MIME type: POST ...
10
votes
2answers
657 views

Behaviour of $D000-$D3FF section on the C64 during bankswitching

My question is about bankswitching behaviour on the Commodore 64. I'm writing a C64 game for a 16kb cartridge with EXROM and GAME pulled low, so the available bankswitching modes are (according to ...
11
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1answer
615 views

Go program for the C64

Is there a program for the C64 that plays the game of Go? Progress on go engines has started later than with chess, so maybe there is no C64 Go software from the 80s, but maybe someone has recently ...
6
votes
2answers
914 views

Does anybody remember a database cartridge for the Commodore 64?

Decades ago I bought a database cartridge for my C64. IIRC it was a no-name brand being sold as close-out or from a bargain bin. It may have been the slowest program I ever bought. It wasn't too ...
20
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2answers
2k views

How to check the C64 graphics mode used by Maniac Mansion

I have been investigating the MS-DOS port of the C64's Maniac Mansion game. The original MS-DOS port used the C64-specific character map to draw the various backgrounds in the game. I noticed that ...
1
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3answers
605 views

Commodore 64 Game with Falling Character Scream

I'm trying to remember the name of a Commodore 64 game that had a character in it that would scream when it fell. I found videos of Impossible Mission, but the name doesn't seem right and the sound ...
10
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3answers
1k views

Why did blanking of screen on C64 SAM enable better quality speech synthesis?

There's this old piece of software still present in today's Windows called SAM that enabled C64 to speak. I remember that we could choose either screen on and worse speech quality or screen off and ...
24
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2answers
2k views

Why does waggling the joystick of a C64 cause errors loading from tape?

When loading a game from the tape drive on a C64, if you wiggle the joystick around too much the program will not load correctly. Is there an explanation for this? EDIT: Perhaps someone can try to ...
11
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4answers
1k views

Looking for an easy to use Commodore 64 disk/sector editor

First, let me say I understand that 'recommendation style' questions can be very subjective, but I believe there is enough value in a few good beginner resource pointers that others could benefit from ...
16
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6answers
2k views

C64 BASIC: How to suppress the '?' sign when using the INPUT command?

When you are getting INPUT in Commodore BASIC it always adds a question mark at the end of the string you want to show. Is there a way to suppress the question mark when using the INPUT command?
10
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2answers
693 views

Why does this BASIC program keep restarting?

Here is a BASIC program for the Commodore 64, which should load the LIB file from the disk, and then stop. Yes? 5 PRINT "LOADING..." 10 LOAD "LIB",8,1 20 STOP the LIB file is 102 bytes long and is ...
7
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2answers
1k views

C64: Strange Behaviour on Control Port 1

I wrote this little Basic program to get Joystick input from Control Port 1. I know that this method is very strange and is better for keyboard input. 20 get a$ 30 if a$="" then 20 32 b=asc(a$) 33 ...
30
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2answers
4k views

C64: Why is POS(π) faster than POS(0)?

According to this article: german C64 Wiki article about the POS() command POS(π) is 20 % faster. Although in my experience it is ...
10
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1answer
2k views

What is this extra lead in my monitor cable?

I have a breadbox Commodore 64 with a Commodore 1702 monitor. My monitor has three RCA-style inputs on the back: Audio (White) Luma (Yellow) Chroma (Red) I purchased a cable which claims to be an ...
3
votes
2answers
566 views

C64, basic v2, DATA strange behavior

I have the following code line: 0DATA"-+-+-" Here "\" and "/" are the ASC codes 205 and 206. I get a syntax error: ?SYNTAX ERROR IN 0 READY. As I can remember, there was same special in the ...
18
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3answers
2k views

Obscure uses of the Commodore 8050/1541 disk drive

When I was working for a foundry consultancy, we did the following Download routines to add delays when writing certain tracks. This was a security feature. When the program started, it would try ...
12
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1answer
494 views

Sprites not rendering correctly before $2000

I am currently testing out some stuff in assembly with C64Studio and Vice and I noticed something with odd sprites. My code starts at $1000 and my sprites at $2000 but when I try to lower the first ...
16
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4answers
2k views

How to use BASIC after “LOAD ”$",8 on the C64

After loading a file list from a floppy disk it is hard to program in BASIC because the file list is interpreted as BASIC lines. For example there can be 20 lines with the number 1, because 20 files ...
3
votes
1answer
270 views

Which material was used for the 6502/6510/8500 MOSFETs?

I know that in the 80s, there was a shift from aluminum gate material to polycrystalline silicon. I wonder because the 6502 was released in 1975 and there were a lot of different implementations and ...
9
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4answers
1k views

What's a safe and easy way to desolder the CPU from C64?

I have probably broken my CPU by connecting 5 V from Arduino (500 mA) to the SENSE Pin of the Casette Port, So now I wonder what would be the safest way to desolder the processor? I have a cheap ...
8
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3answers
2k views

How to develop software for the Commodore 64 with VICE?

I see a very large fan-base and hear a lot (especially here on retrocomputing) about how great the Commodore 64 was. Growing up in the Windows 95/98 era, I seemed to have missed a great era for ...
9
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5answers
1k views

A game where you program a robot to fulfill missions

I'm looking for a game. Unfortunately there're only few things I remember: You had a robot. There was no way to steer it manually, so to solve a room, every step to do had to be programmed in advance ...
13
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1answer
2k views

Number of transistors in the C64

How many transistors are there approximately in the C64 if we consider every chip on it? I think that it is something around 50.000 but I'm not sure.
16
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3answers
1k views

What is the history of DE-9 joystick ports?

The Commodore 64 and the Atari 2600 had compatible joystick ports. Commodore, Atari, and third-party companies like Wico made joysticks supporting that standard. Did this standard have a name? ...
34
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3answers
2k views

Why does the C64's LIST command choke on REM statements with a Shift+L?

On the Commodore 64 and VIC-20, the LIST command will abort with a ?SYNTAX ERROR on any line that contains a REM statement with a Shift+L character. A minimal program triggering the error would look ...
53
votes
2answers
11k views

Why did Commodore fill their power supplies with epoxy?

If you know anything about the Commodore 64 (and other Commodores, really) you know that Commodore really went the cheap route and produced some awful power supplies. The Commodore 128 PSU isn't ...
26
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3answers
3k views

How did the “rub joystick port to continue” in the Creatures 2 infinite lives cheat work?

The game Creatures 2 on the Commodore 64 had an unusual cheat to get infinite lives which unlike most things on the Internet that are said to "really work" really worked! What you had to do was lick ...
116
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2answers
20k views

How did Commodore's anti-Microsoft Easter Egg work?

A couple years ago the Toronto PET Users Group published an article (The Great Commodore/Microsoft Easter Egg War, on p. 7) about a newly discovered anti-Microsoft Easter Egg that Commodore hid in the ...
18
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4answers
2k views

Emulate smooth scrolling

One thing I really liked about the 8-bit (and even most 16-bit) games was that the frame rate was fixed to the vertical blanking. Games were smooth back then. I've been trying to recreate that feeling ...
21
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1answer
1k views

When does the VIC-II read the sprite data?

This question is about the Commodore 64 and its graphics chip, the VIC-II. Imagine that on a particular scanline, the VIC-II needs to fetch 40 bytes (the background tiles) and since it's a badline ...
13
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2answers
867 views

Were 1541s upgraded with more RAM?

Since the Commodore 64 was often used with one or more 1541 drive, and these had CPUs which could run user code, it makes sense to me that these would have been expanded in the day, to have roomier ...
35
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6answers
4k views

What was the purpose and history of the C64's special keys?

I never had a Commodore 64 but I've always been curious what the purpose and history of some of the special keys were. In particular: C= Run/Stop Clr/Home Restore I'm mostly used to the standard ...
18
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6answers
1k views

Is there software that will run across multiple Commodore 8-bit machines without modification?

I noticed in some of the answers in this question that the Commodore 8-bit line apparently used a jump table at $03xx for entry into the kernel ("kernal" for the pedantic) routines. Figuring that the ...
14
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3answers
2k views

What is the “standard” way to implement KERNAL hooks on the C64?

The C64 kernel (or KERNAL as it’s known in the C64 community) routines work via a jump vector table stored in page $03xx. A common programming paradigm to create something like a "device driver" would ...
7
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2answers
830 views

Creating Null Modem Connection between two C64s?

Trying to establish a null modem connection between 2 C64s using 1 Commodore 1660 300 Baud modem and 1 Commodore 1670 1200 Baud modem. Does anybody have detailed instructions on how to configure the ...