of FCC regulations. It can either be attached to a dedicated monitor or a TV set using the external modulator included with the computer. Sound The VIC chip has three pulse wave generators and a white noise generator with an overall volume control and mono output. Each pulse wave generator has a range of three octaves located on the scale about an octave apart, giving a total range of about five octaves. Memory expansion The VIC-20's RAM is expandable through the cartridge port via a RAM cartridge. RAM cartridges were available from Commodore in several sizes: (with or without an included "Super Expander" BASIC extension ROM), , and . Third-party vendors eventually offered expansion cartridges with larger RAM sizes. The internal memory map is reorganized if you plug in and cartridges, leading to a situation where some programs only work if the right amount of memory is present (the most significant divide being between a machine with no or extra memory on one hand, and a machine with more extra memory on the other. Most expansion cartridges featured hardware DIP switches, allowing the RAM to be enabled in user-selectable memory blocks. Since the VIC-20 was designed to use SRAM rather than DRAM, the system board has no provisions for DRAM refresh. Unlike the PET, the VIC-20 does not include a machine language monitor, but Commodore offered them on disk, tape, or cartridge, with several different executables to load into various memory locations. The monitor programs were the same as the PET monitor, but added a mini-assembler instead of requiring the user to enter hexadecimal opcodes. RAM expansion cartridges ultimately allowed adding up to to the BASIC user memory; together with the built-in user memory, this gave a maximum of for BASIC programs and variables. Memory not visible to BASIC could still be used by machine code programs. You could also map of expansion RAM to the address space reserved for ROM cartridges, effectively allowing you to run many cartridge-based games from disk or tape and was thus very useful for software pirates. Reception Describing it as "an astounding machine for the price", Compute! in 1981 expected the VIC-20 would be popular in classrooms and homes with small children, with "excellent graphic and sound capabilities". While predicting the 22-column screen was "too small to support any but the most rudimentary business applications" the magazine observed that "at a price of ,