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Questions tagged [vic-20]

For questions about the Commodore VIC-20

2
votes
3answers
302 views

How does memory addressing/mapping work in 8-bit systems?

If I attach a 16 KIB EEPROM to a 6502 or similar, and put some kind of operating system on it, it will run fine, but won't have access to any other chips. So, when a Commodore VIC20 had 5k of ram and ...
5
votes
4answers
262 views

Cartridge modems - was the Vic-20 a special case?

'The Home Computer Wars' has this to say about the development of the cartridge modem for the Vic-20: The size of the case was another problem. Most modems came in bulky rectangular boxes about 10 ...
5
votes
1answer
275 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,$3E,$...
6
votes
2answers
648 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 $...
18
votes
2answers
2k views

Why does the VIC-20 have 5KiB of RAM?

Why does the VIC-20 have 5 KiB of RAM? Why not a multiple of 4 as any other systems, e.g 4 KiB or 8 KiB. Is there a technical reason for that?
3
votes
2answers
207 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 ...
5
votes
2answers
421 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 ...
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 ...
8
votes
1answer
330 views

What was the difference between “Video Low” and “Video High” on the VIC-20?

I was reading about the Audio/Video port pinouts of the VIC-20 and I noticed that pin 4 is VID L and pin 5 is VID H meaning Video Low and Video High, respectively. I'm familiar with luma, chroma, etc....
10
votes
2answers
480 views

Did the VIC-20 support raster scanline tricks like the Commodore 64?

I've been programming the C64 on/off for over 30 years (wow). However, I have a few VIC-20's I want to program. I never had a VIC-20 as a kid so I haven't had much exposure to them. Am I correct in ...
11
votes
2answers
207 views

Where to find thermal paper for Aquarius or Commodore printer?

The thermal printer that was sold for use with the Mattel Aquarius or VIC-20 / Commodore 64 is an Alphacom VP42. This uses thermal paper, 4 3/8" wide. Original paper for these printers is very ...
13
votes
2answers
430 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?