Questions tagged [commodore-64]
For questions about the different versions and products of the Commodore 64
261
questions
2
votes
1answer
138 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 ...
1
vote
0answers
85 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 ...
5
votes
0answers
168 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 ...
17
votes
3answers
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 ...
6
votes
8answers
441 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 ...
8
votes
1answer
683 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
3answers
4k 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 ...
16
votes
3answers
1k 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 ...
29
votes
2answers
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 ...
2
votes
1answer
251 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 ...
6
votes
2answers
379 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 ...
6
votes
1answer
253 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 ...
9
votes
1answer
335 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
1answer
134 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 ...
4
votes
2answers
460 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 ...
9
votes
2answers
753 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 ...
6
votes
1answer
435 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 ...
24
votes
1answer
706 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 ...
9
votes
2answers
764 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
1answer
266 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 ...
0
votes
0answers
55 views
Can I use a Commodore 64 compatible joystick with my Amiga 600? [duplicate]
I have some Commodore 64 compatible joysticks and I would like to know if I can use them with my Amiga 600. I would just plug it in and try it, but I don't want to short circuit anything.
18
votes
1answer
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. ...
6
votes
4answers
662 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
2answers
240 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 ...
6
votes
3answers
412 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.
...
22
votes
8answers
3k 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 ...
3
votes
1answer
712 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
0answers
130 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 ...
1
vote
0answers
51 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:...
9
votes
4answers
802 views
Delay loop in BASIC
Yesterday I was looking for a way to implement a delay loop on the C64.
I came across this page: https://www.c64-wiki.com/wiki/TIME
At the bottom of the page there is a code fragment that waits for a ...
6
votes
2answers
630 views
Modern heat sinks for Commodore C64/C128
The VIC-II and SID chips in the C64/128 are prone to over-heating and are rather expensive to replace nowadays. Some other ICs in these machines may have the same issue.
An unmodified machine includes ...
6
votes
1answer
183 views
Chaining IRQ's with BASIC & Kernal routines turned off
Having disabled BASIC and Kernal routines I set up an IRQ to run the following code when the raster line reaches 200:
.irq1
inc 53280 // change border colour
// lda #$ff // clear the ...
5
votes
4answers
361 views
Running WarpCopy64 on an emulator
I'm interested in IP networking capabilities of the Commodore 64. I learned there is a tool called WarpCopy64 that can be used to run a simple file server on the Commodore. The server can be accessed ...
8
votes
3answers
668 views
Is it still possible to access a BBS via dial up internet on the C64 (or other retro computers)
I was wondering if it is still possible to access any online BBS using dial up and an 80's era computer.
I'm aware that some dial up internet providers still exist (eg Nippy Internet in the UK), but ...
3
votes
2answers
379 views
What high nibble values can you get when you read the 4 bit color memory on a C64/C128?
The C64 and the C128 have a memory for storing the color values of a character. The size of this memory is 1k x 4bit (2k x 4bit for the C128 which can do a double buffering), thus reading the value at ...
3
votes
3answers
718 views
What are quick ways to load downloaded tape images onto an unmodified 8-bit computer?
There are repositories of tape software available online, for example CPC Power for Amstrad CPC machines.
What is the fastest and simplest way to load such games onto an unmodified computer, with the ...
22
votes
5answers
6k views
How to detect a real Commodore 64, THEC64, or VICE emulator in software?
Some programs notice if they are run on a real Commodore 64 or an emulator. For example, this demo from 2007 stops on VICE emulator 3.2 with the message "No VIC inside". How is this done?
I ...
6
votes
1answer
647 views
Bank switching and memory perspectives (C64)
I've been reading up on bank switching on Wiki and in particular here which contains the below nice image and have a few questions:
Am I right in thinking that LOAD loads into RAM (dark grey in the ...
7
votes
2answers
965 views
Basic / Assembler startup code (C64)
I'm just creating my own .prg file using NCurses Hexeditor in Ubuntu which I load using load"file.prg",8 in Vice. I followed the information in this link explaining how to create a .prg file....
0
votes
3answers
263 views
c64 copy chars to sprite issue
How to do correct copying char to sprite ?
Lets say 1st char is at $2000 second is at $2008 and copying to sprite at $2480.
And with this we can copy 1 char to top left position of 1st sprite. But ...
14
votes
1answer
3k views
Why was the 1541 so slow?
The Commodore 1541 floppy disk drive, sold for use with the 64, was notoriously slow for historical and technical reasons:
Marketing insisted on compatibility with the 1540, the floppy drive sold ...
10
votes
3answers
716 views
How do I get the size of a file on disk on the Commodore 64?
As the title, really. I'm reading a SEQ file into memory, and need to know how big it is ahead of time. I know that I can get the size in blocks by parsing the directory, although it's ugly, but the ...
11
votes
4answers
2k views
Is it possible to just construct a simple cable serial↔︎serial and send data from PC to C64?
I recently saw a video made by the famous "The 8 Bit Guy" about PE6502 computer. At 19:41, he successfully sent a text file from his Windows 95 laptop to the PE6502 using only a standard ...
8
votes
1answer
327 views
Is there a possibility for a user-defined IRQ hardware vector on a Commodore 128 in C128 mode?
When an IRQ occurs, the 6502 microprocessor and its derivatives in the C64 and C128 push the status register to the stack and then load the contents of a two-byte vector at memory address $FFFE/$FFFF ...
5
votes
1answer
175 views
Menu in Octapolis
I have been retrogaming with Octapolis on an emulated Commodore 64. Starting up the game presents a menu offering a choice between one or two players, and between music and sound effects. But I don't ...
0
votes
1answer
144 views
VICE loads files slowly on Fedora 32 Linux [closed]
I lately wanted to try some of the Commodore 64 games I have kept as D64 files on my Fedora Linux system using VICE. I have lately upgraded the system from Fedora 26 to Fedora 32.
After I started up ...
12
votes
2answers
2k views
Why does the VIC-II duplicate its registers? (C64)
After sporadically reading about the C64 and tinkering here and there for over 32 years I finally decided to get to know my C64 memory layout properly. In doing so I have a question about the VIC-II ...
4
votes
1answer
219 views
From what errors could Commodore's tape loader recover
The Commodore PET/VIC-20/C64 tape routines write out the leader for each file twice, and then write the data twice. While it would seem that this should allow data to be loaded more reliably, ...
32
votes
12answers
12k views
Did computer games for Commodore 64 really take "25 minutes" to load "if everything went alright"?
In the Swedish-language song "Nostalgi" by Markoolio from 2003, some of the lyrics go:
My first computer had 64 kB
you surfed on the water, and that's that
The computer games were loaded ...
4
votes
1answer
243 views
Commodore 64 CC65 - I need help with config set up for using a data segment in Bank 3
I'm developing a game for C64 using CC65 to compile my C code to ASM. To get started quickly, I have been defining the data for my sprites in C arrays and then copying the data in those arrays to the ...
