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Questions tagged [commodore-64]

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

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13
votes
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.
1
vote
1answer
2k views

How to add Final Cartridge III to VICE C64/128 Emulator

How do I properly add Final Cartridge III to VICE Emulator? In the file menu, VICE has an item Attach cartridge image... which splits up into CRT Image but also a list of several cartridges, among ...
5
votes
4answers
2k views

How can I implement the modulus operator in Commodore 64 Basic?

How can I implement the modulus operator in Commodore 64 Basic? There are not a lot of math functions to work with, and modulus would be very handy.
6
votes
2answers
722 views

Is there a program I can run on the C64 to speed up booting of a game?

Though I had several friends back in the day with a Commodore 64, I only recently acquired one after a friend gave me his old one before he moved house. As such, I'm diving in to learning about the ...
10
votes
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 ...
7
votes
2answers
839 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 ...
5
votes
2answers
402 views

Method for adding firmware to a Commodore 64 expansion card?

The C64 expansion port can and does support multiple IO devices without conflicts. There is 0.5 KiB that is decoded for $DE00-$DFFF, using /IO1 and /IO2 on the expansion port. As long as the devices ...
12
votes
1answer
947 views

Was the Spartan by Mimic Systems a real product?

I was flipping through an old copy of RUN magazine and came across an advertisement for a product called "The Spartan" produced by Mimic Systems. I had forgotten about this product completely, but I ...
34
votes
2answers
4k views

Why did the C64 have ← and ↑ as dedicated keys?

I've always wondered why the Commmodore 64 had discrete keys dedicated for the ← and ↑ symbols. If I remember correctly, they weren't used in BASIC at all, and were not very useful for drawing, ...
11
votes
3answers
5k views

Visible resolution of C64 video output, including borders

The VIC-II in the C64 outputs 320x200 pixels inside the borders. What is the full visible resolution including the borders? To clarify, I am interested in the full screen size in units of normal ...
22
votes
5answers
5k views

How can I power a C64?

I was chatting with our neighbor and after some long talking, I found out that he has a Commodore 64. I'd love to test it, however I'm not sure how to power it. How can I power a C64?
7
votes
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, ...
5
votes
2answers
582 views

C116 vs C64 cost

The Commodore 116 was the start of the ill-fated TED line of 8-bit computers, which sold poorly (for several reasons, particularly including lack of compatibility with the Commodore 64) until they ...
7
votes
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 ...
7
votes
3answers
783 views

Why do we need to acknowledge the interrupt from VIC-II?

A page on how to do raster interrupts includes the following code Irq: LDA #7 STA $D020 ; Turn screen frame yellow LDX #90 Pause: DEX BNE Pause ; Empty loop that "...
7
votes
1answer
624 views

How did the C64 interface tape drives?

How did the C64 interface tape drives? I'm aware that the external interface was basically a audio input - but how was this audio converted into digital data, and how was it loaded into RAM and ...
5
votes
2answers
449 views

When were sprites first displayed in the border area?

I assume one of the first undocumented effects on the VIC-II was the ability to display sprites in the (upper and lower) border area. I wonder how and when this was first discovered and used? Was it ...
3
votes
1answer
352 views

Is it possible to switch the interrupt source of the C64 to VIC without changing the IRQ routine?

The ROM IRQ routine at $EA31 is usually trigggered by the timer interrupt 60 times a second. Is it possible to switch the interrupt source to VIC and still use the same routine? If yes, which memory ...
15
votes
2answers
987 views

Can a Commodore 64 use two screenmodes on one scanline?

Many games, for example, Maniac Mansion, or Kissenschlacht, use two screenmodes. Oftentimes, a bitmap mode for the main screen, and a text mode for the lower part which displays scores or whatever. ...
6
votes
2answers
1k views

How to exactly sync to the raster line for a vertical raster split?

Motivated by Wilson's question Can a Commodore 64 use two screenmodes on one scanline? I tried to implement a simple example that polls the beginning of a rasterline and then switches the screen mode ...
30
votes
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 ...
5
votes
2answers
657 views

Why does the Commodore 64 leave these pointers in Zeropage?

I'm trying to decide on what I can get rid of from the zero page, so that I can keep my own data there. Looking at this page, documenting what each of the zeropage locations do, I'm trying to figure ...
12
votes
2answers
1k views

Why was BASIC on the Commodore 64 one byte shy of 38KiB?

When you power up a Commodore 64 you are greeted with a friendly message telling the user it has 38911 BASIC bytes free. 38,911 is one byte shy of a 38 KiB (1,024 * 38 = 38,912). What was the reason ...
24
votes
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,...
11
votes
3answers
2k views

How do serial (user port) adapters achieve speeds above 1200bps in C64?

The information I have states that the userport' serial speed is about 1200bps, but there are some carts going up to 9600bps. I would imagine that the 1200 is the limit, so I'm wondering how is the ...
15
votes
3answers
2k views

What graphical effects can be created by changing the VIC-II settings?

I read in this answer that one could create graphics effects outside the usual specifications of the hardware by changing the settings of the machine's VIC-II at specific cycles during the video ...
24
votes
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 ...
17
votes
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? ...
12
votes
2answers
1k views

Does the Commodore 64 have the PHX opcode?

Code written for the Commodore 64 sometimes uses the PHX opcode, which should push X onto the stack. There also are plx, phy, ply. These were apparently added on the CMOS versions of the 6502; very ...
2
votes
2answers
514 views

Using C64 floating point kernal routines with 16 bit integer

How to use floating point kernal routines for 16 bit arithmetics such as: $1234*$ABCD or $1234/$ABCD ?
14
votes
1answer
305 views

C-64 Exchange News Service

I am trying to recall the name of a peripheral I use to have for my C64 in the 1980s. I believe it was called Exchange or X-Change. You hooked it up to your cable TV service and it would decode a ...
4
votes
3answers
1k views

How can I view BASIC code hidden by SYS?

I ran a validation of an old disk, and it turns out this ruined a game (won't load) and deleted my old high score list on David's Midnight Magic. I would like to edit the code to get the high score ...
10
votes
2answers
870 views

6510 I/O port initialisation

TL;DR: With what values are the I/O port registers (locations $00 and $01) on the 6510 initialised when it is powered on? I'm writing a Commodore 64 emulation. The Commodore 64 uses a 6510 ...
3
votes
1answer
348 views

Audio from Commodore 64 to line 1/4 inch line level

I have a 1702 monitor for my C64. I use a cable that splits the video/audio from the C64 to the Red/Yellow/White thing. Something like this. The white cable is the audio. I believe this is an RCA ...
2
votes
1answer
151 views

Can't enable list even with “enable run-stop” poke

Well, I've downloaded an old non-English textual adventure, which of course, "for the sake of professionalism" have list disabled. Even after entering pokes for enabling "run-stop/restore" and for ...
12
votes
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 ...
5
votes
1answer
380 views

1980's ROM used which exp(n) algorithm?

In 1980's ROM (Apple IIe, Commodore 64, VIC-20, ...) which algorithm is used to compute exp(x), and where do the coefficients below come from? (Chebyshev, Remez, Pade, ...) .byte $71,$34,$58,$3E,$...
4
votes
2answers
868 views

Open source, non-GPL SID emulator

I am looking for a SID emulator that is open source, but not GPL. In particular, I am looking for something with a license that allows me to link it to a closed-source program; and also one that ...
45
votes
4answers
35k views

Commodore 64 to modern TV

I've been thinking about getting a Commodore 64 machine. However, I realise there's obviously no video cables I have that will work. But when I looked online there are many people using S-Video to VGA ...
8
votes
2answers
923 views

Is it possible to bank out Kernal in Commodore PET, VIC-20 or 264 series computers?

You can bank out Kernal ROM in C64 using $01 register. This was preferred by game/demo coders who wants to employ self tuned routines and wants to expose ram 'underneath'. You can do lda #$35 : sta $...
10
votes
1answer
621 views

VIC-II transistor count

I'm curious about the transistor count of the VIC-II, the video chip in the Commodore 64. According to http://visual6502.org/wiki/index.php?title=Chips_in_our_collection the Atari 2600 TIA chip has ...
8
votes
3answers
1k views

How to spin up 1541 drive without C64

I have a 1541 drive and I want to make it spin but I don’t have a Commodore computer. I don’t need to read data, I would just like the drive to spin. Can I manually tell it to spin using a raspberry ...
18
votes
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 ...
5
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 ...
2
votes
1answer
285 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 (...
21
votes
3answers
3k views

How can I overclock my Commodore 64?

My Commodore 64 is running quite slow, and my friends want it to be faster, thus overclocking it. But no one knows exactly how to do that. With our current "modern" stuff, nothing seems to help my ...
13
votes
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
votes
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 ...
11
votes
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% ...
8
votes
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 ...