228

I'm the author of the TPUG article. The "BILL GATES SUCKS" message isn't really an Easter egg; that was just a conceit of mine to make the article a bit more interesting and to turn it into a bit of a puzzle. Here's how it works and how it was created: In any given infinite sequence random numbers, it's a mathematical certainty that a given subsequence of ...


61

That's not a real easter egg. Someone just made an effort to find random seeds that produce the numbers to create the intended words. It would be an easter egg if the seed numbers were in some way related to CBM or Microsoft. A=RND(-A) initializes the (pseudo) random generator with A, generates a random number and stores it in A. The GOSUB20 subroutine then ...


59

Epoxy offers two advantages -- it is an electrical insulator, and it conducts heat better than air. Transformers and inductors are generally potted with epoxy for this reason. [ref] Perhaps the cause of the high failure rate is that Commodore engineers decided they could use cheaper components to build the power supplies, depending on the epoxy properties to ...


51

One reason was likely that the VIC-20 and C64 did not have their own displays, but were designed to be connected to a television set. The interface between the computer and the television was not sufficient to display 80 column text (it would have been almost unreadable). However, the PET had its own integrated display so it did not have this limitation, and ...


45

(2017.03.03) I have added a second answer with diagrams and more technical details. This answer is already huge and self-contained; the other focuses on the complexities due to hardware. Why does the C128 perform poorly when running CP/M? The Z80A was sort of an after-thought in the C128 design. Before release it had been touted as "fully C64 compatible" (...


43

I'm trying to identify what kind of machine this is. It looks like an Amiga of some kind, It's a Commodore C64-II also known as C64C: The mouse seams to be an Apple ADB mouse (Type A9M0331), sold from 1986 until the mid 1990s: but I can't read "Amiga" anywhere on the front. Maybe the brand was removed. If you look into the lower right, you'll ...


42

There are several simple precautions that are always worth taking when powering up a vintage microcomputer after long periods of storage or non-use. The minimum, simple steps, should include: Place the computer on an electrically safe workbench, preferably one that includes a grounding strap for the user. A wooden table is an OK substitute, just avoid ...


33

The 6502 was designed and manufactured before Commodore bought MOS Technology, the creator of the 6502. MOS Technology didn't originally plan to build computers. They wanted to sell the 6502 to companies who wanted to build computers. Back then, anyone planning to bring an electronic device to the market wouldn't choose any chip that didn't have multiple ...


30

I'm Linards Ticmanis, the guy who put out the CPMFAST package in 1999 that has been mentioned several times in the other answers (although I go by the nickname TeaRex on here). While creating that, I had to take a deep look into the innards of C128 CP/M, so that I think I can say that I have a rather detailed understanding of the way it works internally (or ...


29

The early versions of Microsoft BASIC required 4KB of ROM The 4k versions lacked a number of major features, including string variables. These were added in the 8k versions. The equivalent 6502 version, which also expanded the floating point from 32 to 40 bits, was about 10k. But Microsoft's IBM BASIC (known as "Cassette BASIC") for the original IBM PC ...


25

Which brand was most commonly used in West German schools? I know Commodore was big in Germany, which would make it a likely candidate, unless nationalistic pressure acted again? There is no simple answer. Not so much due to any 'nationalistic pressure' (*1) but the fact that German schools are not run according to federal guidelines, but are managed on ...


23

The pixels are not exactly square, the actual aspect ratio depends on the TV system. For PAL-B, the pixel aspect ratio is 0.937:1, the pixels are a bit higher than they are wide. For NTSC, the ratio is 0.75:1. At this ratio it can be clearly seen that the cursor block is definitely higher than wide.


23

Use of TV as monitor is the reason for these low resolutions. The issue is that the color resolution of TV is very low. While B&W TV could resolve pixel small enough for ~400 to ~600 pixels, color resolution was much much lower, barely around 200 pixels. Some computers exploited this, such as Apple II and CGA/composite. It also shows the limits of that ...


21

Electricians some times (or used to) do similar techniques when configuring wiring -- once the wires were in place, they would fill the cavity with a non-conductive resin or epoxy, so that the chance of any movement or shift in the wiring would cause a short or a disconnect is greatly reduced. I've seen this in numerous situations myself, including air ...


21

TL;DR The ownership issue is really associated with the trademarked brand and product names, and the copyrighted ROM software, not the processor/co-processor hardware. I think there are two mainstream products who's licensing terms are instructive to understanding how the earlier (non-Amiga) Commodore IP has been used and defended by the new rights holders ...


21

On the C64, no. On power up, the drive is resetting and the motor may spin briefly, but the drive is not actually reading the disk. And even if it were, it is an IEC slave device and cannot initiate communication with the C64/C128 bus master itself. For an auto boot concept to be implemented, it would have to be the computer's kernal directing the flow of ...


20

Quote from VICE manual: Load the specified file into memory. If no address is given, the file is loaded to the address specified by the first two bytes read from the file. If address is given, the file is loaded to the specified address and the first two bytes read from the file are skipped.


19

TL;DR: The computer, or rather its OS, has no idea about a directory, in fact not even what constructs a file. It can only open/read/write/close data streams from devices on the bus. Getting a directory is a clever hack of 'loading' a dummy program. This works since LOAD command is implemented as opening a data stream and loading what is returned into ...


18

My first answer attempts to answer all the OP's questions without going too deep into the hardware details. Since posting that answer, I have had the pleasure of corresponding for several days with Bil Herd, the lead designer of the C128 project. In addition to what I have learned from him, I have done some additional research on my own. This answer focuses ...


18

The 1701 and 1702 are virtually identical. They have the same specs, tube, inputs, casing, and manufacturer. The only real difference is the 1701 is older (1982 to early '83, 1702 is late '83) and the fact that the 1701 shipped with a 5-pin composite video cable instead of an 8-pin luma-chroma cable in the box (both monitors support both inputs). A full ...


18

On a floppy disk, each 'bit' is a flux reversal — a magnetic event. If those bits are too close together, they'll leak into one another and data will be lost. Disk controllers use a regular clock and either write a transition or write nothing at each clock tick. There's also a lower limit on how far apart transitions can be. Disk rotation speed varies ...


18

This example reveals a rounding error under Commodore BASIC V2.0: A=0.3:B=0.6:IF A+B<>0.9 THEN PRINT A+B-0.9 Running this on a C64 yields a difference of 2.32830644e-10. Other pairs that fail are 0.4+0.5, 0.6+0.1 and 0.8+0.1. Please note that also the order in which the numbers are summed up affects the result. 0.6+0.1-0.7 yields a difference, ...


18

'Jeff Porter realized it would not be possible to significantly cost reduce the Amiga 500 to get it into the $250 retail price range'. They could have cost-reduced the A500 - perhaps even to $250 retail - but they would have had to make some compromises that (thankfully) they weren't willing to do. There were a lot of chips on the board. They needed ...


18

The Datassette has a digital interface, and since it is not meant to process audio signals at all, it allows directly writing sharp digital magnetic transitions to the tape, using a single monophonic read/write head. The written pulses are always written at same amplitude, so there is no variation between equipment. Also when reading the transitions off the ...


17

In standard bitmap mode the C64 outputs 320 pixels in 40µs. The visible portion of a line is ~52µs; in 60Hz regions ~240 lines are considered 'visible', but in PAL regions it's ~288 lines. So if there were no borders, there'd be around 52/40*320 = 416 pixels across the visible portion of a line. Given that each line is 4/3rds as wide as a hypothetical ...


16

The 6502 has been used in huge volumes in markets that commodore never cared about competing in much - terminals for large-scale professional computing, printers and plotters (which they mostly bought in from OEMs if sold with their own computers), embedded solutions, test and industrial and scientific equipment, arcade machines ... - just as other 8 bit ...


16

Back in the day, it meant that present versions of the Commodore BASIC and Kernel did not use those locations, but Commodore said nothing about whether future versions of the ROM might do so. Addresses 251-254, by contrast, were specifically marked as available for user programs and Commodore guaranteed that nothing in present nor future versions of the ...


16

To start with, it was of course VC-20: SCNR. In general I'd say VIC-20 would be the most consistent spelling. To start with, Commodore's own technical manual gives a good base, as here was no reason to enhance/mangle it for marketing purpose or textual handling. Next, the VIC-20 was first introduced in Japan as VIC-1001. This hyphenated spelling not only ...


15

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 ...


15

[Insert: Some site history While the German subsidiary (Commodore Büromaschinen GmbH), originally set in Neu-Isenburg near Frankfurt, had facilities for import handling and distribution, this was soon moved to a distribution center in Braunschweig and accomplished by a final assembly line and a development center. At the same time the company moved into ...


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