The Vic-20 was released in 1981. The predecessor of the Commodore 64 . Had a 'slight' memory problem, which was corrected by the 64's large amounts of memory (for the time). The name of the machine comes from the name of the graphics chip, the VIC , which meant Video Interface Chip. The meaning of the acronym was slightly changed to mean 'Video Interface Computer'. The 20 apparently comes from a rounding-up of the total memory of the machine (3 kbytes RAM + 16 kbytes ROM = 19 kbytes). The "20" comes from the apparent rounding up of the memory, but it was actually a reference to the display columns. The display was a measly 20 character display (as opposed to the typical 80 column display we're used to today). I think Commodore eventually realized that 20 was certainly nothing to brag about, so they choose to focus on the memory when naming the 64. In the case of the 64, the name was truly a reference to memory size. I read (somewhere) that Commodore was first just going to call the VIC-20 the VIC, but thought that that was too short, so then they decided to call it the VIC-22, with the 22 taken from the number of characters across the VIC graphics chip and the computer could display. But then they thought that the number 22 seemed "unfriendly" somehow, so arbitrarily picked 20 which sounded "friendlier", hence, the VIC-20. The modem came with some software that loaded through the tape player. There was a small slot on the rear left of the computer to which the modem attached. The slot itself had about eight pins, with a small indentation between some of them; to make the modem fit only one way, right side up, of course. Of course it was awkward, since the screen only displayed 22 x 23, and your typical mainframe was 80 x 24. This caused quite a bit of wraparound.Pitted clock vs. clock, the VIC-20 is actually faster than the Commodore 64 which followed it. The VIC tops at 1.01 MHz while an NTSC 64 runs at 1.0225 MHz and the PAL 64 runs at 0.985 MHz. In fact, this was the source of some incompatibility with the 64 and the 1540 disk drive (the drive intended for the VIC-20). Because of the faster rate, 1540 drives needed to be slowed down for Commodore 64's (and thus the 1541, which was meant to be run with a 64, had to be sped up for VICs). The solution on the 64 end is to blank the screen with POKE 53265,11 when using a 1540 for disk access (which yields the needed speed increase); on the VIC-20 end, to use a 1541, users had to put the disk drive in a special compatibility mode with OPEN15,8,15,"UI+":CLOSE15. This made it a 1540, effectively. Later disk drives such as the 1571 continued to support this to a point, but clones like the Enhancer 2000 and the Excelerator+ did not do this properly.