69

POKE 59458,62 was a trick, sometimes called "Fast Print," used to increase screen refresh rates on older PETs. This page describes the trick succinctly: the system no longer waits for the video sync signal, thinking that it's always present, and updates the screen as fast as it can. In later models this POKE could cause problems. The new video circuitry ...


37

The reason was cost, since neither the original PET nor the TRS-80 required the extra high resolution and finer dot pitch found in more expensive computer monitors. Virtually all of the computer terminals of the time paired a CRTC with a high-resolution green or amber screen to generate an 80x24 text display, as that was the early standard. This required a ...


25

It is well established that Microsoft's 6502 BASIC (and Commodore BASIC is just a manufacturer specific adaption) is a port of the original 8080 BASIC done for the Altair -- alas, not a direct one, as the prior port to 6800 was used as code base (*1). The creation is attributed (in its source code) to three programmers: Bill Gates for the execution code (...


23

The answer, as always, was cost. 'White' CRTs were cheaper because they were used in B/W TV sets. The color itself has no impact on resolution, but TV tubes didn't need to be as sharp so they could be made cheaper. So why were 'high resolution' monitors green or amber? Because these phosphors have a longer persistence so the image doesn't flicker as much, ...


22

It's a little cheaper to build all-in-one units because you only need one cabinet and one power supply, and you need fewer cables and connectors and supporting electronics. And back then, people didn't often have monitors that they could reuse on new computers, just televisions which often had only RF inputs and couldn't produce a sharp image for text. So ...


19

C64 Basic used a CR as EOL for disk files. (source: Commodore SX-64 User's Guide, page 22: “CR stands for the CHR$ code 13, the carriage return, which is automatically PRINTed at the end of ever PRINT or PRINT# statement … ”, and verified by hex dump of disk image showing 0x0d at line end.)


13

You'd be surprised. There were specialist microcomputer shops in the late 1970s. I'm talking now about the UK and the shops that I used to visit. These were either individual shops or small chains, like The Byte Shop. These would sell imported boards from US companies like NorthStar and the many British and European board makers. Before microcomputers ...


13

As Tommy wrote in the comment: There are two different RAM chips, one for even columns and one for odd columns. Both are read and latched in one cycle (ESD and OSD bus), and the latched output of each is then used in turn to drive the character ROM (LSD bus). You can see it in the schematics for the CMB 8032 here (even) and here (odd). The Apple //e used ...


12

BASIC games that use no memory specific code can be ported between different commodore machines. (I did some successfully between PET and C64). Machinecode games could be transferred between some commodore machines if they were written to be portable. I never seen such programs but I found in this wikipedia artikel the following: "The Adventure ...


12

It's part of the BASIC interpreter loop. It reads one byte of the tokenized BASIC program, setting zero flag if it's a colon or a zero byte and clearing the carry if it's a number. You can see it used in the main part of the interpreter loop at address C6B5. I'm not sure why this routine was placed in zero page. It's a cycle (or rarely two) faster to use ...


12

You cannot do that on the VIC-20; not only is no such feature provided by the built-in hardware but there's also no ROMDIS signal on the memory expansion bus or anything else similar. PETs with a 64kb upgrade have a register at $FFF0 for memory selection that allows the ROMs to be paged out (see e.g. "2.2 Control Register" in this document — the 8096 is an ...


11

There were a number of programs that used the 6502 in the 1541 as a coprocessor. An obvious application was for calculating fractals, because that doesn't need a lot of RAM. An example is the Mandelbrot Construction Set (German article). This thread also mentions some more recently written games which used the 1541 as coprocessor, namely The Masque, Panta ...


11

And it's definitely Star Spores. I found an interview with the author, who it turns out lives fairly close to me, and he mentioned the line-drawing routine which I'm sure is referring to the lightning bolt effect. It seems this game has been lost to history. The interviewer mentions trying to find a copy to upload, but look as I might I cannot see it ...


10

The following article details some of the early history of Commodore BASIC (including other Microsoft BASIC 6502 versions), particularly v1 and v2. Create your own Version of Microsoft BASIC for 6502 Originally, Commodore paid a flat fee for Microsoft's BASIC, instead of a royalty license, reportedly because Jack Tramiel told Bill Gates, "I'm already ...


10

This jogged me memory about a pretty well known problem with early PC video control hardware that could, if programmed with really incorrect video timing, result in damage to the flyback power supply in monochrome monitors. Here's a link to a more detailed exchange on the subject of monochrome monitor damage from software: How did this program burn out ...


9

I can't speak to the origin of all dealers, but the one I work for often repeats it's origin story into new recruits. It's "public" knowledge, but may have been self censored, so please take it with a pinch of salt. The founder apparently noticed that computer memory was decreasing by about 5% per month, and noted that he and his friends would mostly buy ...


9

This was indeed Jim Summers who wrote Star Spores. He also wrote Slime and Astro-Rescue. You can find them on my site, with his permission. Star Spores


8

Playing music with the drive heads, of course. I've tried that too, wrecking the drive in the process. Dimming the drive LED, by flashing it very fast, with a variable duty cycle. Printing a file on disk directly to a daisy-chained printer, freeing up the computer to do something else. Direct disk-to disk copy between two 1541 units, similarly to the one ...


8

VIC-20 keyboard seems to have become sort of a standard for [...] the MAX Machine (in membrane form), C64, C16 and (with additional keys added) the 128. The C64 decision was easy, as it was done to save development time - existing part. Similar for the C16. For Max as well for the C128 it was a compatibility issue. What keyboards and layouts did ...


7

You can play with VSync on many systems and cause that situation, but it's unlikely to create damages; on most systems, from the Atari 2600 to PCs until the 486 era, you had ways to do this. There was a French computer called the TO7 that had a module designed to make overlays on top of a composite video signal. This is the only computer I know of, from this ...


7

Reposting slightly, but this (German-language) page provides software for networking C64s via the serial bus, with the simplest intended power-on state being two C64s connected to the two inputs of a 1541, having one set to ignore the drive while the other loads, then reversing that, then having them talk to each other and to the drive through negotiation. ...


7

It seems that the key piece of contemporary technology would be the Commodore VIC-20, released in 1981. Through the use of IEEE-488 adapters, such as the VIC-1112 the VIC-20 was compatible with the Commodore floppy drives. Also, RS-232 adapters, such as the VIC-1011, were common for the VIC-20. Using a contemporary VIC-20 with these adapters, one could ...


7

If the contents of the Scott Adams' adventure cartridges for the VIC-20 are loaded into the same addresses on the Commodore 64 and executed, the games will behave on the C64 just as they do on the VIC-20 except that screen formatting will be a little wonky. If exactly 22 characters precede a line break, the next line will appear appended to the first (since ...


6

The oldest dongle like thing I own is a ROM board for the Apple II from 1978, where the whole PCB with all chips was cast in opaque thermoseting resin. This was ment to secure the software and disencurage any duplication. But tieing Software to hardware to restict usage is much older than microcomputers. Unique identifiers for machines and/or CPUs where ...


6

It seems that Michael Steil at pagefault.org has recently posted an analysis of the KERNAL calls from all of the Commodore 8-bit machines to try and track lineage. However, what is relevant here is the table he includes near the bottom of his blog post that shows which vector entries are safe for which platforms. The result of his findings is that only the ...


6

In addition to the Community Wiki answer: This routine with entries CHRGET and CHRGOT is not only part of the interpreter loop, it used in every statement and function which has to "parse" further data from the BASIC text (program), e.g. for parameters. On some occasions the pointer TXTPTR will be stacked, typically while executing a DEFFN'd function. ...


6

Most of the problems that you list were simply not considerations in the mid-70's. The Commodore PET was not hard to lift safely. Its monitor (in the 40 column variety at least) was tiny and didn't contribute as much to the machine's weight as the vast quantities of sheet steel used in the construction of the case. And don't forget that it was a novelty ...


6

The oldest (smart) hardware "dongle" I know of is from 1985 in the ZX Spectrum 48K. To curb Internet piracy and as a "collateral side effect" also having more 16KB (e.g. 64KB for the game), Mikro-Gen Ltd launched the game Shadow of the Unicorn with an external 16KB (EP)ROM board that mapped on top of the internal ROM address space. This game came with ...


6

A few points to expand on previous answers: In those days, resolution wasn't limited by phosphor, but by video bandwidth (and video memory). A standard TV had a bandwidth around 2-3 MHz, enough to support a PET or APPLE ][ - style 40x24 text display, or about 320x240 dots. The TRS-80 Model I monitor had slight modifications to the video circuitry to ...


6

Don't underestimate the cost of additional RAM for display memory! The TRS-80 used seven, not eight, 1x1024 static RAM chips for its display memory. They left off the eighth chip to reduce cost. Without it, the machine was limited to uppercase-only display -- one bit per character cell to specify whether that cell displayed a character or a 3x2 graphic tile,...


Only top voted, non community-wiki answers of a minimum length are eligible