21

The "PETSCII" encoding is based on keyboard positions of the original PET chicklet keyboard (*1): (Taken from Wikipedia) The keyboard is made similar to basic typewriter keyboards, but ordered in a square fashion, including a top row of symbols but not numbers and a separate numeric keyboard. By every key holding only a single ASCII equivalent ...


12

I don't have any experience with the exact modification you are talking about. However, I think it is a relevant point that the design of the firmware for Commodore microcomputers included a "screen editor" as a separate bit of software from the BASIC interpreter. As far as I know, all the CBM 8-bit machines had this design. So, it is very possible ...


9

I think the codes were laid out so that when laid out sensibly on the PET keyboard, the shifted and unshifted forms of each key would have a consistent relationship. When the VIC-20 reduced the number of keys but added the Commodore key, this made it necessary to rearrange the placement of graphics on the keys; since Commodore kept the same arrangement of ...


9

The garbled screen is normal on startup, but should be replaced by the BASIC screen after a moment. There's a rather detailed troubleshooting guide, including links, at http://www.dasarodesigns.com/projects/troubleshooting-common-problems-with-the-commodore-pet-2001/ I'd suggest that you ignore the spare parts sales pitch at the beginning and work your way ...


4

For what it's worth, I did a quick photo of my C-64 and VIC-20 keyboards, so it's very easy to see the physical grouping of the various graphics/symbols. Commodore C-64 Keyboard: Commodore VIC-20 Keyboard:


3

What I've heard from people who should know, is that it's simply a form of error checking, not error correction. The data is always read twice, but the second time it simply checks that the data read from the tape is what is already in RAM. Most other systems, even at that time, used a CRC to do the same job more efficiently. Of course, you can ...


2

This is anecdotal, so take with a big grain of salt... I have a C-64 power supply that was home-brewed for me by my Dad when I was a kid from the remnants of the original. My Dad, never being one to do anything halfway, did a fantastic job and added a 'voltage adjust dial' and analog meter to the finished supply. This means I can actually dial-down the ...


1

If you restrict your use of BASIC to statements and commands and functions that exist in version 2.0, with no memory-address references (so no POKE, PEEK, SYS, USR, or WAIT), and keep the program small enough to fit into the unexpanded VIC-20's 3583 bytes (including space taken up by variable values during the course of the program's execution), you can ...


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