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0

Locomotive BASIC 1.1 on the Amstrad CPC6128 had a fairly decent FILL command. It wasn't the fastest, but then what FILL routines in BASIC were back then? It would do a decent job of filling complex shapes though. This was one of the differences between 1.1 and the BASIC 1.0 supplied with the CPC464.


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By the time mice wheels became widely available (starting with the Microsoft IntelliMouse; the Genius EasyScroll was earlier, but we can ignore that here), support for DOS was a secondary concern, and the “standard” DOS drivers and tools never supported them. As a result, there are limited avenues for wheel support in DOS itself, and DOS emulation ...


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Woz was exceptional, but not the only one with this (moderate level of ?) skill in machine language. Lots of teens/kids learned to poke (from Basic) absolute hex machine code into memory on several models of personal computers (not just the Apple I/II). I knew some who could speak out-loud a small subroutine in hex for the 6502, no assembly language or ...


37

One thing is certain: Steve Wozniak was very good at hand assembling 6502. Instead of writing assembler mnemonics he could simply type in the necessary hex code. I realize this isn't a proper answer but this anecdote is simply too good to relegate to a comment. It comes from Bill Atkinson remarking on Steve doing some assembler work: The other thing that ...


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TL;DR: As explained on Steven Weyhrich's great and authoritative Apple II History Site, Wozniak simply sat down and wrote his Integer-BASIC (*1) on paper, while assembling it at the same time by hand. In his own words: I had no assembler, that was another thing. To use an assembler, they figured that somebody was going to buy this processor to use for a ...


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Commodore BASIC has a quirk that it will run a FOR loop at least once. This is what allows your t variable to update at least once, allowing the loop to be valid. Raffzahn's explained how it works, but according to BASIC standards, it shouldn't. The ANSI/NBS Special Publication 500-70/1 test suite from 1980 go into great detail about how BASIC should behave. ...


0

From what I can gather, the code should be understood as if it read 10 t=2 20 t0=ti 30 ? "start " t0 40 t=t0+t*60 : t1=t 50 t=ti 60 t=t-5184E3*(t<t0) 70 t=t+1 : if t<=t1 then goto 50 80 ? "end "t where t1 is a hidden variable, invisible to your code. In other words, FOR i = a TO b has neither of the two semantics you hypothesised: ...


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TL;DR: FOR T=<target value> TO T uses T as a temporary variable to store the target value inside the FOR stack frame, where it is used later to compare with the actual value of T after an iteration. This eliminates the need for a second, helper variable. Works whenever T is/can be set within the loop. The Long Read: I imitated the code in CBM prg ...


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40 for t=t0+t*60 to t ... will repeat at least once and then for as long as t0+t*60 (i.e. start time + duration) does not equal t. So this: captures t0+t*60 (the desired end time) such that t can be reused; and after the first iteration, continuously tests ti (which has been stored to t) against the desired end time. i.e. Commodore's implementation of for ...


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Well, this is to be expected; the BIOS Data Area has only four slots for I/O addresses of serial ports, with slots for parallel ports immediately following. In the MEMORY.LST file from Ralf Brown’s, we can find the following entries0: MEM 0040h:0000h - BASE I/O ADDRESS OF FIRST SERIAL I/O PORT MEM 0040h:0002h - BASE I/O ADDRESS OF SECOND SERIAL I/O PORT ...


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The BIOS list only contains addresses of up to four standard 8250-type COM ports found at boot at the standard addresses. It will not contain more than four ports, it will not contain any non-8250 type COM ports, and COM ports at non-standard addresses, such as PCIE COM ports, and USB COM ports which don't have an IO address to begin with. It will not ...


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The BIOS data area only has room for addresses of four com ports, at 40:00 through 40:07. More serial ports would be driven by some device driver with some other place to store the address(es) and IRQ(s).


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