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33 votes
Accepted

Why does the Commodore 64 have 4K of non-banked RAM at $C000?

I wonder why the Commodore 64 memory map was created as it was. As so often it helps to look at a machine's predecessor; in the case of the C64 that's not the VIC 20, but the Max Machine, a very ...
Raffzahn's user avatar
  • 224k
26 votes
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Identify this children's Commodore 64 book

A few more hours of searching finally turned up the book: Larsen, Sally Greenwood. Computers for Kids. Creative Computing Press, Morris Plains, NJ, 1984. ISBN 0-916688-63-1. Larsen produced several ...
Psychonaut's user avatar
  • 7,541
23 votes
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How does the sequence $C3, $C2, $CD translate to "CBM"?

The C64 used PETSCII, not ASCII, as its character set, and most Commodore 6502-based computers had a 'shift' between the normal layout, with uppercase letters at $41 through $5A and pseudographics at $...
Jeff Zeitlin's user avatar
  • 1,563
23 votes
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Difference between machine language and machine code, maybe in the C64 community?

That video probably tries to add a bit too much definition into blurry terminology, at least my opinion. In fact, all three ways he describes are ways of creating machine code, and, at the same time, ...
tofro's user avatar
  • 35k
22 votes
Accepted

What is this unusual syntax for the Commodore SYS command?

Line 40 looks like a typo. It should be SYS 65493 instead of SYS 65439. SYS 65493 ($FFD5) maps to the internal LOAD routine at $F49E Line 10 calls the filename parsing routine PLSV at $E1D4. PLSV ...
Darren's user avatar
  • 650
21 votes
Accepted

Were cartridge slots cheaper at the back?

Maybe it's just that it was a few cents cheaper to build that way. The company was certainly very focused on cost reduction. Yes, it was. Not much, but there are several small savings: The board ...
Raffzahn's user avatar
  • 224k
17 votes
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C64 char screen plot routine - not clear about reason for logical OR

C64 screen memory by default begins at $0400. The ORA #$04 ensures that you are treating location (0, 0) as address $0400, treating the location one to the right of that as $0401, etc. It has the same ...
Tommy's user avatar
  • 37.3k
16 votes
Accepted

Commodore 64 - any way to safely plug in a cartridge when the power is on?

is there any programmatic setup you could do on a 64 that would make it safe to insert a cartridge with the power on ? This calls for a clear No, But :) Why is it Risky? In general it's unhealthy ...
Raffzahn's user avatar
  • 224k
14 votes

Were cartridge slots cheaper at the back?

If a machine has a vertical cartridge slot on the top, it's liable to have junk fall into it unless it either has a door, or unless something is left in it. The Odyssey2 video game system simply had ...
supercat's user avatar
  • 36.6k
13 votes

Difference between machine language and machine code, maybe in the C64 community?

An assembler actually does two important but separate things to help the programmer. One, which you mentioned, is to convert instruction mnemonics into opcodes, based on the addressing mode (e.g., LDA ...
cjs's user avatar
  • 26.6k
12 votes

What is this unusual syntax for the Commodore SYS command?

Three related concepts one should understand when trying to understand Commodore BASIC programs (or other Microsoft-derived BASIC interpreters for that matter) are the CHRPTR address, and the CHRGET ...
supercat's user avatar
  • 36.6k
10 votes

Identify this children's Commodore 64 book

Might be Kids To Kids On The Commodore 64, it's the right format, cover sounds similar, it has stuff about monsters.
Alan B's user avatar
  • 4,620
10 votes

Commodore 64 - any way to safely plug in a cartridge when the power is on?

You can not programmatically setup safe insert/remove cartridges. But there are hardware for enabling/disabling cartridge. By disabling a cartridge on startup, one can prevent cartridge software from ...
wizofwor's user avatar
  • 2,778
9 votes
Accepted

Problem using Commodore 64 BASIC TAB() command in abbreviated form

I wouldn't call it a bug and the solution is kind of obvious: Don't type in the opening parenthesis for tokens that include that already (tab( and spc(), if you abbreviate the function. I.e.: 10 print ...
BlackJack's user avatar
  • 291
8 votes

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

Commodore intended to use the CIA 6526 shift register to speed up the serial IEC bus drastically. There even existed a hacked 1540 with a CIA that was planned to become the 1541, using the fast disk. ...
André Fachat's user avatar
6 votes
Accepted

Commodore 64c supply 9 Vac waveform specs

The 9VAC is just 9VAC out of a 9VAC transformer secondary. Sine wave. 50 Hz since you have an european C64.
Justme's user avatar
  • 33k
6 votes
Accepted

Monitor connector for C64 and ST the same?

The connectors are different, and will not fit. If you look at the ends of the connectors, you should see that the number of pins, and how they are laid out, are different. Specifically, the Commodore ...
Alex Taylor's user avatar
6 votes

Commodore 64 breadbin plastic stands repair options?

Epoxy doesn’t adhere well to nylon but should be ok on the enclosure if you sandpaper the surface a little. Remember that 5-minute epoxy doesn’t reach full strength for 24 hours. A 3D print should ...
Frog's user avatar
  • 1,385
5 votes

Difference between machine language and machine code, maybe in the C64 community?

Short Answer: He 'adapts' his own terms to distinguish between the different 'styles' of programming he wants to show in this video. Long Answer: There is No Simple Answer Well, as so often in real ...
Raffzahn's user avatar
  • 224k
5 votes
Accepted

Sending DOS commands in assembly on my C64

The Commodore Programmer's Manual does not explain this too clearly IMHO, but we find on page 282 of the Reference Guide: "If one of the channels to be closed is to the serial port, an UNTALK ...
Martijn's user avatar
  • 141
5 votes

Commodore 64 - any way to safely plug in a cartridge when the power is on?

From my experience back in the day, inserting a cartridge after loading and running a machine language monitor would more often than not disrupt machine operation, but would occasionally work in such ...
supercat's user avatar
  • 36.6k
4 votes

Commodore "B-series" BASIC?

what is this "B-Series"? I would assume 'B-series' being about the CBM-II series, in the US/Canada usually known as B128 (keyboard style) and B256 (CBM 8296 LP style). The CBM-II series was ...
Raffzahn's user avatar
  • 224k
4 votes

How does the sequence $C3, $C2, $CD translate to "CBM"?

8-Bit Commodore computers starting with the PET (released in '77) used the PETSCII set, which was based on the 1963 version of ASCII rather than the 1967 version used by most machines. PETSCII could ...
gorgo's user avatar
  • 368
4 votes
Accepted

Interfacing with the Commodore 64 IEC Serial Port using Assembly

The IEC kernal (sic!) routines can be found at $ed00, and the RS232 kernal routines at $eeba. Michael Steil has built a very nice side-by-side table of 5 different commented disassemblies which, taken ...
Michael Graf's user avatar
  • 10.1k
3 votes
Accepted

Identify C64 Game About Firemen

This looks like what you describe --> Fire-Drill https://www.youtube.com/watch?v=Xb6oUge6UXU Text from the youtube link: "Each mission is split into four levels: As the fire chief you must ...
mgraham's user avatar
  • 176
3 votes

When did work begin on the VIC-II?

6560 VIC chip was designed for usage in video terminals on 1977. But Commodore could not find a market for the chip. So it was not used. In 1979 MOS Technology began work on two new video chips named ...
wizofwor's user avatar
  • 2,778
3 votes

Synchronising FOR - NEXT routines in C64 basic

It doesn't sound like something that can be done with 3 FOR loops. You will probably end up doing a single loop, and in each iteration of the loop you will be handling separately / independently the ...
Nimloth's user avatar
  • 2,068
2 votes

Commodore 64 - any way to safely plug in a cartridge when the power is on?

Working on the assumption that cartridges are basically PCBs. PCBs (and other connectors) can be designed to be hotplugged, and can be recognised as such by having fingers of different lengths such ...
Mark Morgan Lloyd's user avatar
2 votes

Are pixels on the Commodore 64 square?

EDIT: Disregard the stuff below as regards PAL. I failed to take account of the fact that the PAL C64 uses a slightly non-standard line frequency, which causes the lines on an an analogue PAL screen ...
TeaRex's user avatar
  • 885
2 votes

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

"or any other emulator" would include emulators like SIMH that are meant to emulate old mainframe/minicomputer systems that were supposed to be used with literal terminals - these will ...
rackandboneman's user avatar

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