Talk:Commodore VIC-20
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[edit] Onboard Memory
This article states that the VIC 20 came with 5 KB RAM as standard. However I do believe that it only came with 3.5KB of RAM. Bear in mind that this is based on the UK/PAL version. Also perhaps some of the RAM is taken up by BASIC much like it does on the C64.
Re: Memory Basic free memory is 3.5K on a stock machine (3583 bytes). However, the overall RAM in the machine is 5K plus 1K x 4bits colour RAM for the VIC chip. The operating system uses 1K and screen character memory takes up the remaining 0.5K. 209.5.225.86 19:20, 17 April 2006 (UTC)
[edit] Graphics modes
The article talks about hi-res graphics being available at 160*160. I don't recall there being a limitation on the grid size other than the 176*184 - anyone know differently? —The preceding unsigned comment was added by 193.61.96.249 (talk) 15:45, August 21, 2007 (UTC)
[edit] Commodore VIC-20 A/V
I just fixed my old VIC-20, and I have no idea how to use the A/V cable. I'm not A/V-literate, so I'm having trouble. The color code is red, but that means audio nowadays, so I know something's changed. Anyone have any idea? Thanks. --70.119.19.133 22:47, 12 February 2006 (UTC)
Re: Video cable I have one here. Typically yellow=luma, red=chroma, white=audio. You can safely try all the outputs on cable to the video input of the TV until you get a picture. If none of them generate a picture, you either have a dead VIC or bad cable. Go over to Denial forums for more help (see the links). 209.5.225.86 16:00, 5 April 2006 (UTC)
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- Please use the 'Discussion' section to 'dicuss the article', not your personal technical problems. There are forums to do that.
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[edit] Comments
Moved here this comment from the main page:
(and, frankly, not so unlike the TRS-80 Model I – a possible inspiration?)
At18 19:48, 6 Sep 2003 (UTC)
[edit] Name
Did the 20 in the name have any significance? boffy_b 13:11, 24 August 2006 (UTC)
No, other than it sounded nice to the marketers at Commodore at the time. 209.5.225.86 18:18, 18 September 2006 (UTC)
- Yes. Sorta of. The number was to be VIC-22, based on the screen width, but it was rounded down to 20 to sound friendlier. This was the published story of the day in whatever magazines I had - maybe Compute's Gazette (or Family Computing). --199.3.104.138 15:06, 30 November 2006 (UTC)
Michael Tomczyk is reported as saying: "VIC sounded like a truck driver, so I insisted on attaching a number. I picked ‘20’ and when Jack Tramiel asked, ‘Why 20?’ I replied, ‘because it's a friendly number and this has to be a friendly computer.' He agreed." Source: http://www.old-computers.com/museum/computer.asp?c=252 —Preceding unsigned comment added by JustSomeGuyToo (talk • contribs) 06:18, 8 January 2008 (UTC)
I recall reading in the Programmers reference guide way back in 1982-83 that the "20" referred to the 20K of ROM that the orginal VIC-20 came with. This was later continued with the Commodore 64 (or C64 as is was abbreviated to) but this time the "64" referred to the amount of RAM. (I have just checked for this guide at and found that the VIC-20 ROM was located within the 64KB address space of the 16bit address register as follows: addr (hex)
8000-8FFF 4K Character ROM;
C000-DFFF 8K BASIC ROM;
E000-FFFF 8K Kernal ROM;
Reference: http://www.geocities.com/rmelick/prg.txt, figure 3-5, page 115.) 59.101.2.201 20:52, 4 April 2007 (UTC)
- I've taken the liberty of correcting the above: C000-DFFF, not C000-BFFF as the original writer said. -- 85.183.213.23 21:12, 2 June 2007 (UTC)
[edit] Picture
Is is picture of the VIC-20 actually a VIC-20? Although some later VIC's had grey function keys, the case appears to be a C64 tone. Should we update this perhaps?
- Since this is an Image taken from eBay, a new one is badly needed. The resolution is low, the logo is disturbing and the uploader might not be the photographer. --UbeMarsh 07:26, 8 May 2007 (UTC)
- It's a VIC20 with a Commodore 64 keyboard. I agree a 'real' VIC20 would be better. 203.14.156.193 (talk) 05:04, 23 March 2008 (UTC)
I removed the low-quality eBay picture with a hi-res version I took. Looks much better. This is long overdue. cbmeeks —Preceding unsigned comment added by Cbmeeks (talk • contribs) 00:07, 10 September 2007 (UTC)
- I'm fairly certain some late VICs were manufactured in C-64 cases
Not really possible, since the VIC-20 has a different rear port configuration. However, I have seen late generation VIC's with white cases and 64 grey keyboards. —Preceding unsigned comment added by 209.5.225.86 (talk) 17:46, 11 December 2007 (UTC)
[edit] Binary prefixes
Recently changes have been made to this article to use binary prefixes (KiB, MiB, kibibyte, mebibyte etc). The majority of reliable sources for this article do not use binary prefixes. If you have any thoughts/opinions then this specific topic is being discussed on the following talk page Manual of Style (dates and numbers) in the sections to do with "binary prefixes". Fnagaton 10:26, 25 April 2007 (UTC)
[edit] Why 5K of RAM?
I understand why the 3K "hole" in the memory map exists, given that there are 5K of RAM: you need to have the zero page ($00xx) and the stack page ($01xx) on any 6502 system, and having the built-in memory end at $1FFF makes expansion easier than it would be if the RAM ended at $13FF. But why was 5K memory size chosen in the first place? It would seem that 4K or 8K are the more logical choices. -- 85.183.213.23 21:16, 2 June 2007 (UTC)
- it probably had more to do with cost considerations than anything technical. (i.e. including 6k of ram would have bumped the computer's price up substantially) —Preceding unsigned comment added by 69.125.110.223 (talk) 21:14, 17 December 2007 (UTC)
[edit] Mention of Amiga Computer
The Amiga was NOT a 16 bit computer, but a 32 bit computer. The Motorola 68000 CPU was often called a 16-/32-bit processor, hence the misunderstanding by journalists that the computer would be 16-bitted. The 68000 had at least 16 general purpose registers (data/address) that were 32 bitted. Instructions like "MOVE.L" summoned a 32-bit execution, while "MOVE.W" were 16-bitted. AmigaOS was fully 32 bitted, using a flat memory model, and the 68000 itself had only 24 address lines (for 16 MB max) but the 68020 expanded that to the full 32 address lines (which made memory up to 4 GB possible, in theory). That's why there were Amigas equipped with 256 MB of RAM for graphics and video purposes already in the early 90ies, long before such large memory was used in PCs.
- Not accurate. While the processor in the Amiga 500 is capable of using 32 bit quantities the external data-bus interface to the CPU is 16 bits wide ergo it is a 16 bit computer. For your information the StrongARM processor is capable of manipulating 64 bit quantities with its long multiply and accumulate instructions but this does not however make the Acorn Risc-PC a 64 bit computer. Fnagaton 09:25, 29 July 2007 (UTC)
- By that definition , i386SX would be a 16bit CPU while i386DX a 32bit one, which is clearly not the case. Also many mid-to-high-end GPUs would be 256 or 512bit processors. Not to mention Pentium IV FSB width. (22:28, 31 August 2007 (UTC)) —Preceding unsigned comment added by 83.245.252.197 (talk)
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- Whatever the marketing efforts of compaines selling chips, the strict thruth is that the number of bits of a processor should represent the external data bus. For this reaons the Super NES was not really a 16 bit machine, for example, as it still only had an 8 bit external data bus. At least as I understand it, happy to be proven wrong.Dndn1011 22:30, 1 September 2007 (UTC)
- Read up on http://en.wikipedia.org/wiki/32-bit , http://en.wikipedia.org/wiki/64-bit and http://en.wikipedia.org/wiki/16-bit for starters. A bad compromise would be to take the smallest of a CPUs ALU register width(not 64/128 bit FPU/vector/SSE reg width), address bus width, or data bus width. Sort of works on 32/36/64 bit CPUs (eg. Pentium II/III), not so well on 16/32 bit (386sx, 68000) or 8/32 bit ( 68008, a 68000 variant with 8-bit databus). 193.229.159.16 09:50, 2 September 2007 (UTC)
- Whatever the marketing efforts of compaines selling chips, the strict thruth is that the number of bits of a processor should represent the external data bus. For this reaons the Super NES was not really a 16 bit machine, for example, as it still only had an 8 bit external data bus. At least as I understand it, happy to be proven wrong.Dndn1011 22:30, 1 September 2007 (UTC)
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