For questions about the different versions and products of the Commodore 64
8
votes
3answers
1k 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 ...
5
votes
1answer
254 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,$3E,$...
3
votes
2answers
1k 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 ; &...
5
votes
2answers
316 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 ...
3
votes
2answers
95 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 ...
1
vote
1answer
243 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...
...
6
votes
2answers
620 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 $...
7
votes
1answer
200 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
830 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 ...
31
votes
7answers
8k views
Why did Commodore 64 cartridge games disappear?
The Commodore 64 has a cartridge slot, but by the mid-eighties, cartridge games disappeared; everything was on tape or disk. Why?
One answer that suggests itself is that by that time, a larger ...
0
votes
1answer
184 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 ...
15
votes
1answer
251 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
...
2
votes
1answer
139 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 (...
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 ...
1
vote
2answers
209 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. ...
4
votes
2answers
244 views
How to transfer files to C64 emulator quickly
I just discovered the fun of writing small programs (Basic/asm) for an emulated C64 for me.
Unfortunately, I cannot get used to the emulated C64 keybord, and would like to write the programs on the ...
2
votes
3answers
411 views
Recovering old commodore 5.25" floppy disks
I am noob to all of this, I am trying to relive my childhood.
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 (...
3
votes
2answers
163 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 ...
11
votes
1answer
447 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 ...
14
votes
2answers
2k 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 ...
5
votes
2answers
332 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 ...
9
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% ...
19
votes
1answer
4k 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,...
3
votes
2answers
738 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 ...
2
votes
2answers
338 views
How can a C64 interrupt let the KERNAL keep operating?
I am working on a loading screen, and what I wanted was a simple raster trick (just change the border colour on the bottom half of the screen),
and also call the KERNAL to load some more data from a ...
5
votes
1answer
224 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 ...
7
votes
2answers
167 views
Behaviour of $D000-$D3FF section on the C64 during bankswitching
My question is about bankswitching behaviour on the Commodore 64.
I'm writing a C64 game for a 16kb cartridge with EXROM and GAME pulled low, so the available bankswitching modes are (according to ...
10
votes
1answer
310 views
Go program for the C64
Is there a program for the C64 that plays the game of Go? Progress on go engines has started later than with chess, so maybe there is no C64 Go software from the 80s, but maybe someone has recently ...
6
votes
2answers
561 views
Does anybody remember a database cartridge for the Commodore 64?
Decades ago I bought a database cartridge for my C64. IIRC it was a no-name brand being sold as close-out or from a bargain bin. It may have been the slowest program I ever bought. It wasn't too ...
16
votes
1answer
816 views
How to check the C64 graphics mode used by Maniac Mansion
I have been investigating the MS-DOS port of the C64's Maniac Mansion game. The original MS-DOS port used the C64-specific character map to draw the various backgrounds in the game. I noticed that ...
0
votes
2answers
295 views
Commodore 64 Game with Falling Character Scream
I'm trying to remember the name of a Commodore 64 game that had a character in it that would scream when it fell. I found videos of Impossible Mission, but the name doesn't seem right and the sound ...
4
votes
3answers
441 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 ...
20
votes
2answers
960 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 ...
10
votes
4answers
480 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 ...
9
votes
3answers
474 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?
9
votes
2answers
419 views
Why does this BASIC program keep restarting?
Here is a BASIC program for the Commodore 64, which should load the LIB file from the disk, and then stop. Yes?
5 PRINT "LOADING..."
10 LOAD "LIB",8,1
20 STOP
the LIB file is 102 bytes long and is ...
6
votes
2answers
925 views
C64: Strange Behaviour on Control Port 1
I wrote this little Basic program to get Joystick input from Control Port 1.
I know that this method is very strange and is better for keyboard input.
20 get a$
30 if a$="" then 20
32 b=asc(a$)
33 ...
24
votes
1answer
3k 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 ...
8
votes
1answer
574 views
What is this extra lead in my monitor cable?
I have a breadbox Commodore 64 with a Commodore 1702 monitor.
My monitor has three RCA-style inputs on the back:
Audio (White)
Luma (Yellow)
Chroma (Red)
I purchased a cable which claims to be an ...
2
votes
2answers
225 views
C64, basic v2, DATA strange behavior
I have the following code line:
0DATA"-+-+-"
Here "\" and "/" are the ASC codes 205 and 206.
I get a syntax error:
?SYNTAX ERROR IN 0
READY.
As I can remember, there was same special in the ...
14
votes
3answers
635 views
Obscure uses of the Commodore 8050/1541 disk drive
When I was working for a foundry consultancy, we did the following
Download routines to add delays when writing certain tracks. This was a security feature. When the program started, it would try ...
11
votes
1answer
258 views
Sprites not rendering correctly before $2000
I am currently testing out some stuff in assembly with C64Studio and Vice and I noticed something with odd sprites.
My code starts at $1000 and my sprites at $2000 but when I try to lower the first ...
7
votes
2answers
433 views
How to use BASIC after “LOAD ”$",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 ...
3
votes
1answer
179 views
Which material was used for the 6502/6510/8500 MOSFETs?
I know that in the 80s, there was a shift from aluminum gate material to polycrystalline silicon. I wonder because the 6502 was released in 1975 and there were a lot of different implementations and ...
6
votes
4answers
497 views
What's a safe and easy way to desolder the CPU from C64?
I have probably broken my CPU by connecting 5 V from Arduino (500 mA) to the SENSE Pin of the Casette Port, So now I wonder what would be the safest way to desolder the processor? I have a cheap ...
3
votes
1answer
284 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 ...
6
votes
4answers
520 views
A game where you program a robot to fulfill missions
I'm looking for a game. Unfortunately there're only few things I remember:
You had a robot. There was no way to steer it manually, so to solve a room, every step to do had to be programmed in advance
...
12
votes
1answer
786 views
Amount 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.
13
votes
3answers
584 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? ...
24
votes
2answers
1k 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 ...
