Questions tagged [commodore-64]

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

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14 votes
3 answers
2k views

Why was the VIC-II restricted to a hard-coded palette?

The MOS VIC in the VIC-20 and the MOS VIC-II in the C64 were capable of outputting 16 colours drawn from a hard-coded palette. It's clear that the palette size was fixed at 16 colours as a memory-...
  • 6,722
2 votes
1 answer
143 views

How to fix the inaccurate mouse movement in the Eye of the Beholder for C64 under VICE? [closed]

I'm trying to play the C64 and C128 versions of the Eye of the Beholder by using the VICE emulator on Windows 11, but the mouse movement is too inaccurate and it constantly flutters on a moving ...
  • 573
5 votes
1 answer
236 views

Why can't the VIC-II handle ECM and Multicolor at once?

On the Commodore 64 there are a few different graphical mode selection bits we can enable. This question is about three of them: Multicolor mode (hereinafter MCM), where pixels are joined pairwise ...
12 votes
2 answers
650 views

Why does the FRE() function in CBM BASIC v2 return negative values?

On Commodore machines featuring CBM BASIC v2, the FRE() function to query the amount of memory available to BASIC returns a negative number when the result exceeds 32767 bytes: This quirk does not ...
  • 6,722
5 votes
0 answers
147 views

What percentage of the SID was control versus voices?

I'm interested in specifics of the design and manufacturing of the SID, the sound chip of the Commodore 64. There is a good die photo here http://www.visual6502.org/images/8580/...
  • 53.4k
9 votes
1 answer
399 views

Are the 16 linear steps of the SID Sustain and Filter Volume/Resonance steps of 6.25 or 6.666666667?

The SID has various registers that are described as 16 linear steps: The Filter Volume, The Filter Resonance, and the Sustain of the voice envelopes. The SUSTAIN levels range from zero to peak ...
  • 930
22 votes
6 answers
3k views

Did home computers have mechanical interfaces to typewriters?

In the April 1985 issue of Ahoy!, a reader asks whether it is possible to hook a conventional typewriter up to his Commodore 64. Surprisingly to me, columnist David Barron answers that such ...
  • 6,722
2 votes
2 answers
339 views

Software to generate C64 BASIC code printing PETSCII art

I am looking for a good toolkit to auto-generate C64 basic code, which eventually prints different PETSCII graphics. I am wondering, if there is a good workflow for this, e.g. using a graphical ...
12 votes
3 answers
1k views

Commodore 64 noises during loops, flash load and others

When I was a child, I had a Commodore 64 always connected to a TV via the RF Out. I remember that when running a BASIC program, there were certain noises to be heard. Especially when a longer FOR loop ...
2 votes
2 answers
196 views

How do I save data from a program with CC65 [closed]

I wanted to have a calculator program be able to save a set of answers on a floppy disk or tape but I have no idea what I should do. I am aware that the "cbm.h" library can be used to load ...
3 votes
1 answer
836 views

Commodore SX-64 White screen

I recently acquired a Commodore SX-64. It powers on, but the CRT just displays a white screen. I dont have a test cartridge yet, not that it would help as thereis no display. I havent tried an ...
  • 371
1 vote
0 answers
122 views

Telnet BBS — server side with Synchronet [closed]

I have restored a Commodore 64 and equipped it with a "WiFi modem", which allows me to connect to Telnet BBS sites over the internet. So far so good for the client side. Server-side, I am ...
  • 365
2 votes
1 answer
309 views

Obtaining a CPU execution trace on a Commodore 64 [closed]

I need to collect the execution trace of all instructions executed by the 6502 on a C64. I tried C64 Debugger, but I couldn't find any option for this. Is it possible to obtain with C64 Debugger? Are ...
  • 311
6 votes
1 answer
474 views

How should I set CCGMS on my Commodore 64 to login to a Linux machine?

I have a Strikelink WiFi modem for the C64 (see here and here) and I can connect to a BBS without issues using CCGMS 2017 v4 and the following settings: Baud = 9600 Modem Type = UP9600 / EZ232 For ...
  • 243
1 vote
1 answer
155 views

How to send and receive messages between modern computer and Commodore 64 via WiFi? [closed]

I want to be able to connect from my Commodore 64 to a Linux Raspberry Pi. The ideal solution would be something like ssh that allows me to use the linux machine using the c64 as a terminal but the ...
  • 243
20 votes
6 answers
3k views

Does lossy audio compression damage datasette data?

I grew up with the C64 and had software on cassette tapes. These days, you can find "backups" of this software all over the internet, even in mp3 format (by recording the audio signal with a ...
7 votes
1 answer
304 views

Are SID Players practically almost full-fledged C64 Emulators?

There are many stand-alone audio players (and plugins for general audio players) out there for many systems that play the music of the Commodore 64 that is famous for its SID chip. I believe many of ...
  • 1,029
8 votes
1 answer
394 views

How does the VIC-II/CPU memory access work on the C64?

As a programmer I knew that on the C64 the CPU got the bus in the high phase of PHI2 and the VIC-II got it in the low phase and also stole extra high phases when required. However, it wasn't until ...
17 votes
1 answer
399 views

Was any commercial end-user software written in PROMAL?

PROMAL is a procedural programming language from the 1980s. Its designer, Systems Management Associates, released compilers for the Commodore 64, Apple II, and IBM PC. The language and development ...
  • 6,722
9 votes
2 answers
921 views

Did Commodore ever produce gray colored Commodore 64?

The Commodore 64 was produced for a 12 years from 1982 to 1994. It had several iterations of case color, keyboard color & keyboard labels, badge etc. Commodore was famous for using whatever parts ...
  • 2,534
10 votes
1 answer
247 views

Commodore / Apple II GEOS Document Cross-Platform Compatibility

As I have never used Graphic Environment Operating System (GEOS) on an Apple II (only I on a Commodore 64), I have always wondered were the documents created (from programs such as GeoWrite and ...
2 votes
1 answer
215 views

Does C64 /DMA assertion immediately disconnect the CPU from the address bus?

I have heard several claims (in the comments on this question and answers) that asserting the D̅M̅A̅ signal on the Commodore C64 cartridge port will immediately take the CPU off the bus by deasserting ...
  • 22.9k
2 votes
1 answer
208 views

Timer B Interrupt occurs only once

I was following this tutorial on Commodore 64 timer interrupts and tried to replicate it (except all I was planning on doing was changing the border color.) I noticed that my interrupt only occurs ...
  • 1,566
0 votes
0 answers
253 views

Identify this old C64 soccer game with "speaker"

In "modern" games (Fifa 98, Fifa 2000, PES, etc) you can hear the speaker talking about the match. This was near impossible in the C64 era, but I remember a soccer game that had a speaker ...
  • 877
8 votes
0 answers
314 views

Identify C64 Game About Firemen

I'm searching for an old game for the C64, it was about a group of firemen. I last played it in the 1989, 32 years ago, so I do not remember it very well. I remember only that the firemen don't want ...
  • 877
17 votes
3 answers
5k views

How did the Commodore 64 show a picture while reading cassette?

I was watching this video just now https://www.youtube.com/watch?v=I0YmJluYb6Q&ab_channel=NostalgiaNerd on things that early home computers displayed on the screen while reading cassettes, and ...
  • 53.4k
6 votes
8 answers
892 views

Would a multi button controller have been possible on the C64?

One thing I felt letdown the C64 for many games was the lack of multiple buttons on the joystick, meaning you had to keep the keyboard nearby, (or by your foot!) So you could press space-bar or ...
  • 1,016
8 votes
1 answer
876 views

Why was Carrier Command for the ZX Spectrum superior to the C64 version?

The ZX Spectrum version of Carrier Command has 3D rendering, while the Commodore 64 version, despite a greater amount of RAM, was inferior in comparison. You open the in-game map and there's Google ...
17 votes
3 answers
5k views

How can I store a machine language program to disk on a C64?

I know I can use LOAD "PROGRAM",8,1 to load a program in a certain spot in memory, using the first two bytes of the file on disk. Now let's say I have used the .MON command on the Final ...
17 votes
3 answers
2k views

6502 ORA not updating the accumulator

Unless I'm reading the manual incorrectly, the following should produce $11 when D404 = $10 (I'm turning on the gate for voice1 which has been previously set to triangle wave %00010000/$10) 00153 ...
  • 273
29 votes
2 answers
4k views

What is the Commodore 64C "France version" and why does it need a beefy resistor?

While perusing the schematics for the Commodore 64C (titled COMMODORE-64 B/NE) I came across a suspicious section of the power supply: The unregulated "9V" is connected to the completely ...
  • 1,695
2 votes
2 answers
339 views

How to properly convert an active-low joystick routine to active-high

My last question wasn't specific enough so I'll rephrase it. I've been having trouble with programming game consoles/computers like Commodore 64 that have active-low joysticks, where the bits are all ...
  • 1,566
6 votes
2 answers
430 views

Flash border color during Kernal LOAD routine

I would like to use the Kernal's LOAD routine to load a file into memory, because that seems to be the easiest way to do it. However, that LOAD call is synchronous in the sense that it returns once ...
  • 2,593
6 votes
1 answer
271 views

Commodore 64 sound seems to freeze at a high pitch if executed too soon after startup

I created this little sound driver for sound effects, it makes a classic "laser beam" sound you would hear in old arcade games. There's just one problem, and it's a bit of a strange one. I ...
  • 1,566
10 votes
1 answer
426 views

Confusion in the VIC-II registers

I am playing with my old C64 and fiddling with with VIC-II registers. I am using the great Programmer's Reference Guide, but there is something I don't quite get. According to the register map, addres ...
3 votes
1 answer
143 views

Spontaneous movement and game crashes from active-low joystick routines [closed]

I've noticed this recurring problem when I'm trying to program joysticks or buttons that are active-low (0 = pressed), like on the Commodore 64 or Game Boy Advance. Regardless of the language or ...
  • 1,566
4 votes
2 answers
642 views

How to wait for vBlank on Commodore 64

I'm not new to 6502 Assembly but I am new to the Commodore 64. I'm used to the NES where you have to write everything yourself, such as the NMI/RESET/IRQ vectors, etc, but from what I understand the ...
  • 1,566
9 votes
2 answers
964 views

How to repeat a string in C64 BASIC V2?

I would like to achieve the following: I ask for a number from the user, run a loop number times, and in each loop run, output the string like this: -STR$ --STR$ ---STR$ ----STR$ -----STR$ I tried to ...
  • 93
6 votes
1 answer
472 views

Is this SpeedDOS chip mounted right in my C64?

I have removed a chip to reseat it, but sadly I forgot how it was placed on my C64 (breadbin). I assume its text should be in the same direction of all the other chips on the board, but now I don't ...
  • 243
24 votes
1 answer
975 views

How did the C64 lockup bug and its workarounds work?

The Commodore 64 suffered from a strange bug that caused it to lock up when typing in the full-screen BASIC editor. To trigger the bug, position the cursor on the last line of the screen, type enough ...
  • 6,722
10 votes
2 answers
1k views

How can I connect my Commodore 64 to an RGB+Sync signal via SCART?

I would like to connect my Commodore 64 to my SCART switcher (Shinybow SB-5525), which is connected to a Sony PVM via RGB+Sync. I bought this cable, only to realize after getting it, it is a composite ...
5 votes
1 answer
447 views

Why is my Commodore 1541-II stuck showing "Searching for $" whilst trying to load the directory?

I have a Commodore 1541-II drive. I bought this drive used (but like new) a year ago and I used it on my Commodore 64 for about 6 months, but I moved and just reconnected it to my Commodore and it no ...
19 votes
1 answer
2k views

What's the deal with Commodore's RESTORE key?

Most early microcomputers provided either a dedicated key (e.g. Apple ][), keyboard combination (e.g. PC clones), or dedicated hardware button (countless examples) to "Reset" the computer. ...
  • 58.8k
6 votes
4 answers
785 views

C128D shorted Composite and Ground

I just did a stupid thing and connected a new cable without inspecting it first. It was from a reputable seller, but has shorted pins 2 and 4. What is the potential damage it could have caused and ...
4 votes
2 answers
329 views

C64 KERNAL Loading into I/O space [duplicate]

On a Commodore 64, if I Load "*",8,1 and the file's address (first two bytes on disk) is $D000, will it load to the RAM under the I/O space? In other words, does the KERNAL loader properly ...
7 votes
3 answers
492 views

New chess engines on retro hardware

Does anyone know of any efforts to write modern chess engines for old hardware? (e.g. C64, A2e?) I'd love to see how a pared-down Stockfish or Leela that could fit in RAM could do rating wise etc. ...
  • 1,160
23 votes
8 answers
4k views

Why did the VIC-20 and C64 have only 22 and 40 columns when the earlier PET had 80 column text?

When I was a kid, the "real" computers in movies looked so cool with that 80-column monochrome green text. My first computer was a VIC-20 and it always felt very "toy-like" to me ...
  • 465
3 votes
1 answer
885 views

Problems Connecting an Arduino Uno to a Commodore 64 Joystick Port

I have made up a DB9 connector with connections to an Arduino. I am using pins 1 to 4 on the connector. On the Arduino I have a small program which writes out a series of digital HIGH signals to the ...
2 votes
0 answers
155 views

Running Codenet on a Commodore 64 Emulator

I finally managed to get basic networking stuff working on VICE, thanks to another thread on Retrocomputing. I'm now wondering how to setup a Codenet server emulation. I was able to identify four ...
  • 191
1 vote
0 answers
82 views

How to Perform RR-Net MK3 Detection on VICE Commodore 64 Emulator?

RR-Net documentation describes a detection algorithm for the MK3 model. The algorithm is supposed to reveal the last four hex digits of the MAC address. According to documentation the MAC address 28:...
  • 191

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