Questions tagged [commodore-64]

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

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6
votes
1answer
156 views

Reconstructing uncompressed program from compressed tape image

I have a C64 program in a .t64 file. If I load it into an emulator, what I see is that it loads into a cracktro, which then proceeds to uncompress (taking several seconds at 100% speed) the original ...
5
votes
1answer
107 views

Could a double-sided Commodore disk be written to be used as a “flippy” on a 1541, without requiring flipping on a 1571?

Although the 1571 is capable of reading and writing both sides of a disk, accesses to the second side using the second head will be performed with the drive spinning in opposite direction from how it ...
10
votes
1answer
495 views

Is it possible to boot C64/C128 from floppy

When powered on 1541 reads the disk for a brief moment. Is it used to boot system from floppy? Is it possible to create a bootable commodore 64 floppy?
10
votes
4answers
707 views

Did any devices use the Commodore 64 joystick ports as outputs or two-way communications ports?

Looking at the schematic and explanation of how the C64 joystick ports work, it seems clear that the stick direction and button lines (JOYA0, through JOYA3 for port 1 and JOYB0, through JOYB3 for port ...
3
votes
2answers
298 views

How were games and programs written for the C64 in assembler in the 80s? [duplicate]

Were developers using monitors like e.g. "Supermon+64", "Merlin 64" or "Monitor$C000" and cartridges like "Final Cartridge", "Action Replay" (both of ...
15
votes
3answers
2k views

C64/PETSCII block graphic symbol: was there ever a logical reason for their “ASCII” codes?

You know those block graphic symbols that allows you to draw lines, corners, intersections, fine bar charts, etc. they are useful and one can do a lot of stuff, but their code arrangements always ...
4
votes
2answers
134 views

Joystick adapter from 9-pin to USB

I have still a couple of old C64/Amiga joysticks and I'd like to use them on the New C64, which has USB ports. Is there an adapter from 9-pin male to USB? This 3-year old article references a company ...
116
votes
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 ...
3
votes
2answers
124 views

Is there a Commodore 64 Fastloader/Fastsaver combination that is SD2IEC-compatible?

There exist many fastloading systems for the Commdore 64/VC 1541 combination. Unfortunately, only a few work with the cost-efficient SD2IEC device, a most notable exception is the Dreamload loader ...
20
votes
5answers
3k views

What kind of television set would work with the Commodore 64?

I found out all my SmartTVs don't work because they are too modern for my old computer. I am a young owner of a Commodore 64, so please bear with me as this machine is a decade older than me. I do ...
16
votes
0answers
631 views

Oxford C compiler for Commodore 64

I kept one floppy from my Commodore 128 (which I used mostly in C64 mode), which is written Oxford C compiler. It is a 5.25" floppy. Don't ask me why I kept just this one; probably because I ...
1
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0answers
63 views

Expansion Port & Final Cartridge et al - Are they just programs in ROM, or is there more to it? [duplicate]

For the C64, there are a lot of emulation devices floating on (Euro) ebay that allow you to load programs from SDcard via emulated serial floppy or/and tape interfaces, simulating the insertion of a ...
0
votes
1answer
109 views

Any Public Videos of Anyone Playing Jupiter Mission 1999?

When I was growing up, I played a game for the Atari 800 entitled "Jupiter Mission 1999", which has as a premise that you wake up in the middle of the night with astronauts at your door and ...
5
votes
1answer
213 views

Why are the CBM control codes for color setting so spread out?

The control codes (my C64 handbook actually calls them ASCII codes) for color changing on the Commodore 64 are as follows: Color Control Code Color number BLACK $90 0 ...
3
votes
2answers
205 views

Is there a way to blank out a portion of a screen on Commdore C64?

I would like to blank out a couple of lines between two given rasterlines. Above that I'm planning to have a scrolling background and sprites, below that is a textual info area. I'm thinking of a ...
17
votes
3answers
841 views

Commercial C64 software implemented in Forth?

There has been several implementations of Forth that were running on, and targeting, the C64. Were there any commercial software releases (not throw-away hobby projects or in-house utilities) that ...
9
votes
5answers
1k views

C64 cartridge emulation with ATmega

As a personal project I had the idea to create a custom cartridge for my Commodore 64 and use an ATmega 1284p microcontroller to emulate eproms and/or custom chips. Basically my idea is similar to ...
7
votes
2answers
186 views

(Lack of) identifying IRQ sources in C64 interrupt handlers

I'm trying to learn about C64 interrupt handling (with the goal of putting it in practice). My understanding is that interrupts can be triggered by different sources but there is only one interrupt ...
26
votes
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 ...
41
votes
4answers
5k views

Why are C64 games inconsistent with which joystick port they use?

The Commodore 64 has two DE-9 joystick ports. If I'm the only person that ever plays games on it, you would assume that you could just leave a joystick plugged into Port 1 and be done with it. However,...
7
votes
3answers
323 views

How can I view an Error Info Block in a D64 image?

I've been imaging old C64 floppies using a 1541 disk drive connected to my old Pentium III via a homebrew parallel cable and the Star Commander. Given that my disks are 30+ years old, I am amazed ...
3
votes
2answers
146 views

Printing German umlauts with cc65

I want to print German texts with umlauts with a compiled C program on the C64. I'm aware that these characters are not in the charset and that I will have to change the character set. However, it ...
16
votes
5answers
789 views

Why the disparity between the screencodes and the character codes?

The Commodore 64, and possibly others, I don't know, have character codes (These map integers to characters, in the same way that ASCII does) and there are screen codes (The offset which the VIC-II ...
5
votes
1answer
307 views

Adding control characters to string constants in ca65 assembler

According to the cc65 documentation, a string constant in assembler programs can be defined with the .ASCIIZ command. However, I could not manage to sneak control commands in, for example, the ...
16
votes
2answers
2k views

Is there a Commodore 64 emulator that can profile running code?

I am developing some software for the Commodore 64, and I am concerned about its runspeed. Is there an emulator that can report, after running my code, where exactly it spent most of its time? I'm ...
4
votes
3answers
1k views

What are D64, T64, D71 and D81 files?

The docs for the Ultimate-II+ expansion cartridge for the Commodore 64 state: It is able to read D64 files, as well as D71 and D81 files (no partitions), T64 files. So what are D64, T64, D71 and ...
15
votes
2answers
3k views

How do C64 cartridges swap running programs without losing state and context?

I recently picked up a 1541 Ultimate II+ for my Commodore 64 and have been amazed at how this device seemingly can do every flash memory and other enhancement feature for the machine, short of CPU ...
2
votes
1answer
147 views

What is the file that VICE refers to as dos1541?

VICE needs a file called dos1541 if you want hardware emulation of the 1541 disk drive. What does that file contain, exactly? The 1541 seems to have two ROMs: a DOS and a KERNAL. But if I take the ...
8
votes
4answers
2k views

Commodore 64 with red and white RCA cable

After discovering my old Commodore 64 in the garage, I wanted to test if it still works. The power light comes on but the video connection to a modern TV is obviously an issue, as mentioned here. Well ...
3
votes
1answer
81 views

How to pass a value to an inline assembler script in a #define macro in cc65

I'm trying to add a compact #define macro in a cc65 program for performing various low-level tasks efficiently. For some of the macros, I need to pass a non-constant value to the assembler part. I ...
3
votes
1answer
210 views

Commodore 64 board dimensions

What are the dimensions of the C64 motherboard? I am specifically asking this because I am considering using a 64C case (these still seem to be in production) for an 8-bit homebrew machine. I wonder ...
1
vote
0answers
160 views

Thinking through the design of a TTL video card: what memory chips and how to manage memory? [closed]

Inspired by Ben Eater's "Let's build a video card" aka "World's worst video card" two part projects on YouTube, I was inspired to consider designing a display adapter for my passive backplane TTL mini-...
16
votes
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?
7
votes
1answer
465 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 ...
0
votes
0answers
67 views

Composite video from C64 not being picked up by a modern Smart TV [duplicate]

I've purchased a Commodore 64 "as-is" from eBay. I tediously cleaned out the interior and removed all chips and dusted them out and put them back together. Still, no signal. Except for sound. So, I ...
1
vote
1answer
224 views

How can I link a BASIC program with BASIC 3.5 for C64?

In the magazine 64er from June 1990 a BASIC extension for running Commodore Basic V3.5 on the C64 was presented. The extension is available at csdb. However, to run a BASIC 3.5 program, it is ...
10
votes
1answer
777 views

Why did the C64 use a separate “CAN” +5 V power supply for some chips?

The Commodore 64 had two separate +5 V power supplies: one supplied by the external PSU brick and a second one generated on-board from the 9 VAC via a 7805 regulator. This second +5 V power supply was ...
23
votes
3answers
4k views

Could you manually eject a floppy quick enough to prevent data loss?

I have the vague recollection of "Panic Ejecting" floppy disks by lifting the latch on the drive after immediately regretting a command I had typed. At the time, I was young, impulsive, and blessed ...
5
votes
2answers
966 views

What sort of SBC is in the C64 Maxi?

Curious as to what model SBC this unit is using https://retrogames.biz/thec64 8 bit guys teardown says the internals are 'an ARM computer similar to a Raspberry Pi' https://youtu.be/kxx2F4ffmeE
7
votes
2answers
747 views

What does Shift-RETURN do on Commodore's 8-bit computers?

Someone recently commented that, "a shift-Return is really different from a normal one. It moves the cursor to the next line, but does not complete an input operation." This would be interesting and ...
12
votes
2answers
295 views

Was the Commodore 128 movable zero page / stack and second block of color RAM actually used?

The Commodore 128 hardware allowed two things that weren't possible on the C64: Moving the 6502 zero page and 6502 stack to another place in RAM besides pages 0 and 1, and switching the CPU and/or the ...
34
votes
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 ...
5
votes
3answers
397 views

How can I use the Commodore KERNAL to print a character to the screen?

The routine at 0xffd2 which is called chrout will print a character to some output stream. I would like to use this call to print a message to the screen, but I have a file open for output on a disk. ...
8
votes
5answers
2k views

Was the output of the C64 SID chip 8 bit sound?

Was the output of the C64 SID chip 8 bit sound? I know that SID is not sample based, but instead generate its sound using sine waves and white noise. So is it correct to say that the audio ...
15
votes
4answers
746 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 ...
4
votes
1answer
246 views

What is the largest RAM expansion for Amiga or Commodore? [closed]

What is the largest RAM expansion being manufactured today for Amiga and Commodore 8-bit?
13
votes
2answers
3k views

How did I fry my SID chip?

I recently got a SID chip (8580r5) for $35 and got it playing music. I was really happy about it. I hooked up a small amp chip to the 9V supply momentarily (it didn't work, I was building that part of ...
7
votes
1answer
498 views

Does the Commodore 64 power switch have a history of failing?

My original (1983?) Commodore 64 (brown breadbox with grey function keys) has trouble powering on. Specifically, when I flip the power switch the power LED will glow dimly and the machine fails to ...
10
votes
1answer
1k views

How fast are transfers between the C64 and the 1541 floppy drive?

I am developing some software for the Commodore 64, and my intention is to use the 1541 as a coprocessor. I'll have the 1541 compute some data for me, and then retrieve this data over the serial line. ...
8
votes
3answers
633 views

What are my options for fast bidirectional transfer between a C64 and a 1541?

Since asking a similar question, which is really exclusively about using KERNAL to transfer between disk drive and computer, comments, answers and others hint at the fact that using the KERNAL really ...

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