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Questions tagged [commodore-64]

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

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18
votes
3answers
4k views

Are pixels on the Commodore 64 square?

Are "tile pixels" the same size as "sprite pixels", and are they both square (ignoring the rule that multicolor sprites can only be colored in groups of two pixels)? By "square" I mean that the ...
3
votes
0answers
108 views

Commodore tape drive performance specs

Over the years during which Commodore sold tape drives, there have been a few different versions of the drive with different analog electronics. I'm interested in experimenting with "turbo" tape ...
8
votes
4answers
664 views

How do you play “The Sentinel”?

Many, many years ago, we had a game for the Commodore 64 called "The Sentinel". I remember reading the instructions and being utterly baffled as to how you actually play the damned thing! Hopefully ...
3
votes
1answer
313 views

The Sentinel (aka The Sentry) on Commodore 64 - why was scrolling so fast?

On the Commodore 64 3D games which use one of the bitmap screen modes were notoriously slow. However watching a gameplay video of The Sentinel will show that in the first-person view, looking around ...
5
votes
4answers
884 views

Is it possible in Commodore BASIC V2.0 to configure the system so that the PRINT command does not update color?

The PRINTcommand in Commodore BASIC V2.0 (the one that runs on the Commodore 64) prints each character to the screen address (which is set by the byte in address 648) as well as putting the current ...
4
votes
3answers
199 views

ca65 vs tass syntax: converting a hex address to decimal?

Most of the tass example programs start with a header like this, which places BASIC code at the beginning of the file that has an appropriate SYS instruction to run the rest of the application: * ...
10
votes
1answer
1k views

What sort of RAM chips did the Commodore 64 use in 1994?

For the first few years after its release in 1982, the Commodore 64 used eight RAM chips of 64kbit each. In the late eighties, it became cheaper to use a pair of 256kbit chips of the 4-bit-wide ...
5
votes
1answer
215 views

SID, sampled sound and bad lines

The SID could play sampled sound by poking a click into the chip at an appropriate frequency, and some Commodore 64 games like Ghostbusters and Impossible Mission did this (though only for a few ...
2
votes
1answer
232 views

What was the die size of the 6581 SID?

The MOS 6581 SID, the original version of the sound chip in the Commodore 64, was according to Wikipedia, 'produced in 7-micrometer technology to gain a high yield; the state of the art at the time ...
16
votes
1answer
2k views

Can I use all features of a Commodore 1571 external drive from a C64?

I know that the Commodore 1571 drive works perfectly well with a C64, since the 1571 will detect it is connected to a C64, and will enter 1541 emulation mode. After which, the 1571 just behaves as a ...
8
votes
3answers
941 views

Are there any open-source C64 DOS wedges and fast loaders?

The ever-so-popular EPYX Fast Load cartridge for the Commodore 64 included a DOS wedge (adding commands such as $ to list the files on a disk, /filename to load a file and @ to show the disk error ...
20
votes
3answers
5k views

6510 clock rate of C64: Why was it considerably slower than the 6502 of the Atari 800?

According to Wikipedia, the Atari 8 bit series had a 6502 running at ~1.8 MHz. Why was the clock speed of the 6510 for the C64, which was designed a couple of years later, considerable slower? Was the ...
34
votes
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 ...
3
votes
1answer
244 views

How to write directly to the Commodore 64 (or similar) DAC [duplicate]

I read some related information in a SAM question but I want to know exactly how to write amplitudes directly to the DAC, sample by sample, like in a bytebeat formula. I understand it is possible on ...
18
votes
1answer
932 views

Any difference between a VIC-1541 and a C64-1541?

I have both a beige VIC-20 styled VIC-1541 disk drive and the later brown C64 1541 drive. Is there a difference between them (besides how they look)?
10
votes
3answers
794 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 ...
8
votes
2answers
1k views

Why did certain color combinations look terrible on the Commodore 64?

As I recall, on the Commodore 64's text mode, if you chose certain colour combinations, the letters would be badly obscured by some kind of interference which seemed to affect each character cell ...
15
votes
1answer
758 views

Under what circumstances would RAM locations 0 and 1 be written and/or read on the C64?

To be clear, I'm talking about the actual memory cells at addresses $0000 and $0001 in the DRAM chips. Devices can of course initiate read or write requests to these address on the address/data buses ...
4
votes
1answer
1k views

How did “RAM” cartridges for the C64 work?

Section 7.1.1.2 of the VICE manual mentions that cartridge slot 1 (of the four slots 0, 1, Main and I/O) in the emulator is special in that it's designed to support "mostly RAM-based cartridges" (of ...
4
votes
1answer
427 views

SID to WAV converter that exports per channel separately

For a C64 SID project of mine (https://soundcloud.com/c64er) I was using an converter almost 10 years ago, but it is missing now with its name... I researched many sites, but no lucky. Is there any ...
9
votes
4answers
957 views

How is PETSCII used by assembly-language programs?

First, a bit of context. I wrote an interactive disassembler for 6502 code that, among other things, attempts to identify ASCII strings automatically. Appropriate source code for different assemblers ...
16
votes
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 ...
11
votes
3answers
734 views

Commodore 64 with partly working keyboard (part 2)

I have a C64 that has recently stopped responding to two 'columns' of keys, namely '9,0' 'i,o' 'j,k' and 'n,m' - I've swapped the CIA chips (U1 and U2) to no effect, so I pulled a keyboard from a ...
8
votes
1answer
414 views

Origin of VIC-II (PAL) chip labelled 8656R2?

Wondering why a C64 VIC chip (fully functional) that I got off eBay had an 8565R2 label fitted on top of it: I peeled it off to find this: I haven't ever heard of a VIC-II (PAL) labelled MOS 8656R2. ...
13
votes
2answers
899 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 ...
9
votes
1answer
432 views

What is the C64 disk drive “Jiffy” protocol?

There seems to be something called the "Jiffy protocol" used for some fast load systems. I know of the JiffyDOS product, which seems to require replacing ROMs in both the C64 and the drive, but it ...
9
votes
1answer
603 views

What is the exact bus protocol used by the C64/C128 REU?

The Commodore 64/128 RAM Expansion Units used a DMA controller to move data between the REU's RAM and system RAM (or I/O space). One would set the addreses, length and direction for the transfer (or ...
19
votes
1answer
2k views

How does the C64 get an accurate TOD clock on 50 Hz power?

The C64 has two Time of Day (TOD) clocks, one in each of its 6526 CIA chips U1 and U2. These calculate time based on a 60 Hz or 50 Hz input to the TOD pin (pin 19); the clock input frequency assumed ...
3
votes
1answer
443 views

How to read disk files using CBM specific functions in cc65 with proper error checking

TL:DR What is the reason my kernel_read() function ignoring file errors? I'm trying to understand how to work with files in cc65 using CBM specific functions. My target is Commodore 64 with 1541 ...
7
votes
2answers
683 views

Get exact position of raster beam on C64/C128

By reading register $D012/$D011 or when pausing the execution of an emulation in VICE starting the monitor and entering io d000, it is possible to get information about the current rasterline. For ...
6
votes
2answers
830 views

Commodore monitor to VGA or HDMI

I have this monitor, which I think is a Commodore 64 monitor. I would like to connect it to a pc. Anyone know how to convert VGA or HDMI to this connector format? I've tried searching, but so far I'...
4
votes
1answer
3k views

Where to buy an 8 bit computer remake? [closed]

I want to buy a remake of an 8-bit computer, e.g. the ZX-Spectrum or c64. Must haves: Modern monitor output(e.g. HDMI) Modern keyboard, no gum keys Modern storage, e.g. SD card or USB stick, etc... ...
9
votes
4answers
914 views

Which cartridges were typically used together on Commodore 64 systems?

It's possible to extend the Commodore 64 expansion port bus with boards like the [Aprospand-64]: This example dates from 1986, but there appear to have been a number of contemporary expanders, and ...
7
votes
2answers
487 views

Is it safe for C64 cartridges to respond to read and/or write requests on “unmapped” addresses?

According to the C64 wiki, asserting G̅A̅M̅E̅ on the cartridge port (and not asserting E̅X̅R̅O̅M̅) of the C64 leaves three blocks of the C64 address space "unmapped": 28 KB @ $1000 (otherwise RAM), 8 ...
9
votes
3answers
3k 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 ...
18
votes
2answers
732 views

What was the end of line convention for text files on the 8-bit Commodores

A two part question: Did an agreed upon convention for end of line (EOL) within text files exist on the 8-bit Commodores? If there was a convention, what was it?
7
votes
1answer
1k views

Could the Commodore 64 have used the 6522 VIA instead of the 6526 CIA?

The VIC-20 used a 6522 VIA chip with a couple of 8-bit PIO ports, a couple of timers and a (buggy) shift register. (The bug in the shift register could be worked around with external hardware or in ...
1
vote
0answers
106 views

What cable do I need to connect my old commodore64 with a tv (as monitor) [duplicate]

I want to use an old commodore64. In the 80s we connected a small tv, as a monitor, but the cable for that connection is missing. What kind of cable connection do I need?
37
votes
3answers
4k views

Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?

In short, 3 µm looks like it was the "standard" process size at the time, and it was available to Commodore before the chips were designed. Therefore it looks like using the larger 5 to 7 µm process ...
10
votes
1answer
690 views

How did the Sinclair compare on price with the C64 in the UK?

As far as I know, the popular low-end home computers in the UK around the mid-1980s were the Sinclair ZX-Spectrum ("Speccy") and the Commodore C64. I know the BBC micro also had a following, but my ...
10
votes
3answers
2k views

Why do they use CLI in an IRQ routine?

I am studying an FLI routine in http://codebase64.org/doku.php?id=base:fli_displayer and I noticed that the CLI instruction is being used in this IRQ routine: irq0: pha ... cli ; &...
11
votes
1answer
1k views

Understanding C64 Character Memory

I'm trying to understand how video memory worked on the Commodore64 in text mode. I see that the VIC-II has a memory setup register (at $D018) that keeps track of some of this information along with ...
20
votes
12answers
5k views

Did early assembly games use hardcoded memory locations?

In the era of C64, Apple][ GS, and SNES, did the games use hardcoded memory locations, or did they let the assembler help them (like modern assemblers)? If yes, how did they manage the memory?
4
votes
1answer
193 views

Pac-Man-like: Playing a Excavator bucket or mining drill on a cable

I remember playing this game on the C=64 in the late 80s or so. It was 2d 'platformer' arcade game where you have to clean the screen from pills like Pac-Man, but in a different way. You would always ...
17
votes
2answers
844 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 ...
3
votes
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. ...
6
votes
1answer
377 views

Where are the pullups for the Commodore 64 keyboard matrix lines?

I'm looking at the schematic and the Service Manual for the Commodore 64. I can't seem to find a schematic for the keyboard itself. It seems clear that the control port 1 joystick has normally open ...
12
votes
6answers
2k views

Is there a C64(or any other) emulation that can be run in terminal?

I was looking for a C64 type computer that can be used in the terminal. Can I code one or is there one on the interwebs?
11
votes
1answer
2k views

Which C64 games support two buttons?

CIA 6526 chip used in Commodore 64 is capable of controlling two separate joystick buttons. But the second button should be connected through paddle pot input. This option was not popular till the ...
11
votes
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 ...