Questions tagged [commodore]
Commodore Business Machines and their products. Use more specific tags like [commodore-64] or [amiga] instead if appropriate.
128 questions
3votes
0answers
138views
What might cause my Commodore 1541 and FSD-1 disk drives to have a bus conflict
I'm seeing some strange behavior on my Commodore 1541 and FSD-1 disk drives. Both drives seemingly work fine when attached to the C64 by themselves, but if I set the FSD-1 to be device 9,10 or 11 - ...
- 10.4k
1vote
1answer
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Reduced Circuit C64 Clock Generator newer motherboard Y1 frequency question
The C64B, C, and E motherboard’s 250425, 250466, and 250469 all have the reduced oscillator circuitry when the Y1 crystal is connected directly to the 8701 Clock Generator. This clock generator has an ...
- 21
6votes
1answer
363views
How to detect if the KERNAL load/save routine is currently active on a CBM system?
On a Commodore 64, I have a custom interrupt routine running in parallel with a main program, and I need to detect if the KERNAL is currently performing a LOAD or SAVE operation via I/O. Unfortunately,...
- 4,541
3votes
1answer
152views
Amiga Forever fullscreen mode is display on second monitor instead of first monitor [closed]
I'm using Amiga Forever on Windows 11 with two monitors. Now I have a recent new problem with the fullscreen mode in Amiga Forever (It used to work correctly). If the Amiga Forever program is on ...
- 373
17votes
5answers
2kviews
Unix tools for manipulating Commodore CP/M disk images
I'm looking for some (command-line) tools that can transfer host files on a Unix or Linux machine to and from Commodore .D64, .D71 and similar image files in CP/M format. The particular use case I ...
- 28.5k
11votes
1answer
801views
How are the unused bits within the Commodore 1541 DOS filetype byte handled?
I am curious to learn more about how the original Commodore 1541 DOS handles the filetype byte. This byte is the first byte for every directory entry on disk, and is not only interpreted as the ...
- 10.4k
5votes
2answers
358views
Amiga 500 left mouse button is not working. How to diagnose and fix it?
I've recently bought a Amiga 500 (A6 board). This Amiga works perfectly and starts as it should, except for the fact that when I hover on a icon and click my left mouse button to open it, it doesn't ...
3votes
2answers
232views
How to interface with W65C51 UART
I want to build my own computer with retro-ic's. One of those ic's that I want to use is the W65C51 from Western Design Center. I am trying to connect it to a Arduino to learn how to interface with ...
7votes
1answer
338views
Commodore 128 bottom row of keys work with different shift keys
I have been playing with a Commodore 128 that I picked up but I have noticed one, what I would call, weird keyboard problem(?). If I scan on the bottom row of the keyboard every other key works with a ...
- 73
4votes
1answer
461views
Why didn't Commodore run the 6502 at 2 MHz? [closed]
The Atari 800, in 1979, ran the 6502 at 1.79 MHz. That rounds to 2, and was presumably a 6502A rated for 2 MHz, underclocked. Why did Commodore keep running their 6502 computers at 1 MHz, even the 64 ...
- 64.5k
17votes
5answers
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Why was the 1540 a computer in its own right?
The Commodore 1540 disk drive, along with its better-known successor the 1541, is a computer in its own right, with its own 6502 CPU. Why was it designed like that? It adds significant cost to the ...
- 64.5k
8votes
0answers
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The works of Frontier Manufacturing
Having spent the last however many decades believing Commodore Semiconductor Group was a simple rename of MOS Technology, I just watched a video – quite interesting in its own right – which casually ...
- 64.5k
3votes
0answers
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What process node enabled the 6502 to reach 2 MHz? [duplicate]
The original version of the 6502 was rated for 1 MHz, but before the end of the decade, the CPU was available in a 2 MHz version. Presumably what changed was Dennard scaling: make the transistors ...
- 64.5k
1vote
1answer
317views
What was the RVS key used for on early PCs?
Some Commodore CBM and Sharp MZ-80B keyboards (U.S. version) feature an RVS key, which is linked to an LED on some keyboards (similar to Caps Lock). German CBM keyboards seem to feature a Control key ...
- 557
5votes
0answers
151views
Seeking information regarding how/when Commodore would refurbish a disk drive
I recently added a Commodore 1581 3.5" floppy disk drive to my collection. Being interested in the history of my new toy, I wondered what I might learn from it's serial number. After some ...
- 10.4k
