How many Commodore 64 computers were really sold?

Nobody doubts that the C64 was the greatest selling single computer model of all time, it even made it into the Guinness Book of World Records, but nobody quite knows how many it really was: Most sources say 17 million, others say 22 or even 30 million. With a high degree of confidence, I can now say that Commodore only sold 12.5 million units – how I would know that, you ask, and how do I dare to contradict well-known facts? By analyzing serial numbers! read more

Commodore Plus/4, C116, C16 (TED) Technical Documents

The Commodore Plus/4, the C16 and the C116 from 1984 were members of the 6502-based “TED” series, named after the 7360 TED (“Text Editing Device”) video controller. The TED systems were basically the low-cost cousins of the C64: The overall system architecture and the video chip are very similar to the C64’s, but they lack certain features like hardware sprites. On the other hand, there are some added features like extra colors and more control over the internal timing of the video chip. read more

Final Cartridge III Undocumented Functions

The “Final Cartridge III” has been among the most popular Commodore 64 extensions, providing a floppy speeder, BASIC extensions, a machine language monior, a freezer and even a (rarely used) graphical desktop. The major advantage compared to other C64 cartridges is the consistent way in which the Final Cartridge III extends the C64 experience. read more

Measuring the ROR Bug in the Early MOS 6502

The MOS 6502 CPU was introduced in September of 1975, and while the documentation described the three shift/rotate instructions ASL, LSR and ROL, the ROR instruction was missing – the documentation said that ROR would be available in chips starting in June 1976. In fact, the reason for this omission was that the instruction, while being present, didn’t behave correctly. Only few 6502s with the defect are in existence, and nobody seemed to have checked what was actually going on in these chips. read more

Why is there no CR1 – and why are control registers such a mess anyway?

If you want to enable protected mode or paging on the i386/x86_64 architecture, you use CR0, which is short for control register 0. Makes sense. These are important system settings. But if you want to switch the pagetable format, you have to change a bit in CR4 (CR1 does not exist and CR2 and CR3 don’t hold control bits), if you want to switch to 64 bit mode, you have to change a bit in an MSR, oh, and if you want to turn on single stepping, that’s actually in your FLAGS. Also, have I mentioned that CR5 through CR15 don’t exist – except for CR8, of course? read more

Who invented the computer?

  • In 1837, Charles Babbage designed a general purpose computer, the Analytical Engine, but never built it.
  • Between 1934 and 1937, Church, Turing et al. defined the general purpose computer, but didn’t design one.
  • In 1941, Konrad Zuse built the first general purpose computer, the Z3, but didn’t know it was general purpose and didn’t use it that way.
  • From 1943 to 1946, Mauchly and Eckert finally built a computer, ENIAC, that was designed to be general-purpose.