Remarks: One-Liners

From Maze

One-liners such as 10 PRINT are curt, minimal BASIC programs written to illustrate, represent, and express ideas. Due to their brevity, they must often exploit resources which exist in the underlying platform. For example, 10 PRINT relies on graphical images called PETSCII contained in the ROMs of the Commodore computers. The single line of code itself contains no data pertaining to the curves or pixels comprising the / and \ images. 10Print merely uses the numbers 205.5 and .5 to refer to characters number 205 and 206. Those two numbers are indexes into the "block graphics set" which the 8-bit home computers used to draw simple graphics. This feature, common to the Commodore video display hardware and many other platforms, but not the original Dartmouth BASIC system, kept the program very short.

• Icicle Storm

Block graphics sets - such as the non-typographic / and \ symbols used in 10Print - have collectively allowed a non-alphabetic visual vocabulary to flourish, one capable of representing emotions, stick-figures, space travel, balance sheets, graphical window systems.

In one-liners, sometimes symbols are interpreted as the subject of the story. For example, in this variation on 10 PRINT, one of the slanted symbols is reinvoked, this time to represent an icicle, an illusion which takes some imagination and relies on the default color scheme of the BASIC environment (light blue ice crystals against a dark, foreboding azure, dusk sky) and a synthetic interpretation of movement:

10 poke 1024+rnd(1)*1000,78: goto 10

Icicle Storm relies on the RND command as well as "screen memory," the grid-shaped arrangement of memory locations which corresponds to the PETSCII graphics as they appear on a monitor.

Part of the impression of movement and space-filling are features inherent to the medium. Specifically, the slow, ruthless instantiation of symbolic icicles mimics the dynamics of a mounting storm because the computer can not draw them fast enough to fill the screen instantly. For narrative purposes, it would be possible to slow down the drawing, but not (without resorting to extra-BASIC code execution or upgraded hardware) to speed it up. In a similar way to Icicle Storm's window gradually filling with frozen snow, 10Print presents a cinematic representation of an experience. The pace of that experience islinked to the slow and steady synthesis of their ultimate images.

This one-line simulation may represent the accumulating energy of a storm, but it will never, like a real storm, die out and warm up. After completely filling the screen, the action ceases, so the one-liner can only tell one part of a story.

In a slight variation of the program, Alphabet On Screen:

10 poke 1024 + rnd(1)*1000,1+rnd(1)*26: goto 10

• Windy Day in Chicago

In addition to using external graphics to maintain brevity, BASIC one-liners tend to rely on the random number generator command RND. In Icicle Storm, the unpredictable nature of the random number generator emulates the natural physical process of precipitation.

This random nature can be combined with another hardware feature of the Commodore 64, the VIC-2 chip. Together they create the following example which exploits the side-scrolling video chip inside the Commodore 64:

10 poke 53248+22,int(192+4+3*sin((time*3.456+rnd(1)*.5))): goto 10

• Random SID Tones

As noted elsewhere, the BASIC included with the Commodore 64 included no specific commands such as PLOT and SOUND for controlling the video and sound hardware. As a result, simple sound programs, such as an audio equivalent of 10 PRINT, which plays a juxtaposition of alternating tones balanced evenly between two opposing piano notes is much longer than one line. This is partially because, as seen in line 20, the program must supply or perform its own calculations to create, the additional data pertaining to the desired note. It is not possible, as in the case of 10 PRINT, and other one-liners like Icicle Storm, to supply an index into a reserve of information.

10 poke 54296,15:poke 54277,190:poke 54278,248

20 a(0)=17:a(1)=37:a(2)=21:a(3)=76

30 q=int(.3+rnd(1)*1):print q;:poke 54273,a(q*2):poke54272,a(q*2+1)

40 poke 54276,17:for t=1to75:next:poke 54276,16:for t=1to150:next

50 goto 20

Another way to go about probing the capabilities of complex chips like the Commodore 64's VIC-II and SID registers is to simply write random values to them. IN THE CASE OF THE VIDEO CHIP THIS MAY BE UNSAFE. According to the Programmer's Reference Manual certain values must not be altered, but you may safely try it in an emulator.

Randomize VIC-II (video chip) 10 poke 53248+rnd(0)*46,rnd(0)*256: goto 10

Random SID (sound chip) 10 poke 54272 + (0*ti+(rnd(1)*25)),(rnd(1)*256)and255:goto 10