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19

In composite video, a scanline has the following format: Every line has: a sync mark, which is the lower level, on the left. a color burst, which I'll explain below. video data. The sync mark is used to tell the TV set to bring the beam back to the left side of the screen. At the time TVs were black and white, you had the sync mark and then the video ...


14

Unplug the soldering iron again. It's not really worth it. For one the Z80 operations are less flexible, but more important, they are also slower (clock by clock or cycle by cycle, as you prefer) than their 6309 counterparts. Nonetheless, these Z80 additions over the 8080 core were nice additions to simplify programming in assembly as well as compacting code ...


12

Colour in NTSC is represented as the high-frequency part of the signal. A colour-aware TV will separate the low and high frequency parts. The colour decided will depend on the relative phase of the colour signal and the colour burst, a brief period of pure signal from the retrace period. Therefore the ability for a computer to affect colour decoding depends ...


11

Based on the absolute dearth of information on the Motorola 68486/68487 video chipset (RMS), I would conclude that it was never officially released as a product for OEMs, and was therefore never used in any actual computer products. [UPDATE: Per OP finding, it appears that one company, Micro Concepts of the UK, was offering an SBC based on the 68000/010 ...


11

The TRS-80 Color Computer 1 and Color Computer 2 only supported RF output to a TV. It wasn't until the CoCo 3 that both composite and RGB output were added - RGB being essential for the new 80-column text and higher resolution graphics. Naturally, there are composite monitor-compatible signals inside the CoCo 2, upstream of the in built RF modulator. And ...


11

If you have a Multi-Pak, put the Program Pak in Slot 1 and set the switch to slot 2. Turn on the Multi-Pak and then the Color Computer 3. type: PALETTE RGB to set the proper color set. type: POKE 65407,0 to switch the Multi-Pak to slot 1. The game will then automatically start with the proper colors.


10

Thanks to RichF's answer I looked for information specifically on booting OS-9 and found that you definitely did have to manually launch even an alternative operating system. From OS-9 Level Two Operating System page 2-2, "Booting OS-9": However, this DOS is not a filename and this is not how you load or run any other program. These are the normal ways: ...


10

Neither CoCo nor Retro-Apples are my specific area of expertise - I'll try to answer from a more European viewpoint. Concepts and technical solutions are similar, however. Basically, all the technologies you describe that allow the adaptation of more memory than the CPU would normally be able to address are, at least in my terminology, denoted under the ...


8

Let's sort out some different kind of color artifacts. 1) The composite signal carries both lumincance and chrominance, the latter encoded in the phase of the color carrier. That means if it's somehow possible to change the composite signal quickly enough, it will affect the color. This is not a consequence of the bandwidth limitation of luma and chroma (...


6

I can't speak to BASIC09 specifically, but there's quite a difference between an "i-code" and a tokenized form. At a minimum, the i-code, in the end, need not look at all like the source code, whereas the tokenized form effectively IS the source code. Many BASICs, when you type LIST, simply parrot back out the tokenized data in long form. With i-code, you ...


6

Yes, the Z-80 has block move instructions for memory, I/O and searching. These were additions made by Zilog and were more definitely not available on the Intel 8080. Nominally the Z-80 accesses devices though a different I/O address space using special IN and OUT instructions. There's nothing stopping the Z-80 from using memory mapped devices but the ...


5

Despite being believed as too slow, LDI- and LDIR-like commands in Z80 actually do their best in moving bytes. LDI takes 16 cycles in total, specifically 4+4 cycles to read the opcode, then 3+3 cycles to read and write memory and finally 2 cycles to house-keep, which includes incrementing HL and DE and decrementing BC, as well as setting several flags ...


5

The Microware Assembler has no way to inform you of why it is issuing a warning. It keeps track of the total number of warnings, and also of the number of warnings on each line. If a line has any warnings, then when it is listed the assembler puts the "W" flag on that line1. At the end of the listing, the assembler prints the total number of warnings. ...


5

IIRC there was no need to boot the operating system. It was in the ROM as part of the machine's BASIC. There were actually two choices, with Extended Color Basic being in the more advanced machines. A disk would simply provide access to files, sort of like a fast, random access tape. There was at least one alternative operating system which would load ...


4

The simplest way to get going with BASIC09 would be to get the NitrOS-9 "ease of use" edition. Then if you have a CoCo 3 with 512K RAM and a CoCo SDC (which lets you keep disk images on an SD card), or have MAME or the VCC emulator set up to emulate a CoCo 3. (On the off chance that you have a Matchbox CoCo, an FPGA-based system that Roger Taylor has created,...


4

With some Google sorcery, I finally located a system that used the elusive RMS chip set: The Microbox 3 manufactured and sold by UK-based company "Micro Concepts" from Cheltenham! I can only find it described in detail one place and that is in the Electronics & Wireless World issue of May 1986. On page 63, it is announced as the British rival to the ...


4

I think these are the necessary features: Color burst, or the ability to 'draw' before the left border Pixel rate higher than the colour clock, possibly a multiple and in phase No low pass filters on the composite output Here some data I collected for various home computers: Amiga: can do NTSC artifacts. The machine already had plenty of colors therefore ...


3

For NTSC artifacting to be useful, the dot clock must be a multiple of chroma clock; on all systems I know of where it's useful, it's either 2x or 4x. Further, for purposes of artifacting, there are four different ways that systems can handle horizontal and vertical timing: Horizontal = chroma/228; vertical = anything near 262 Horizontal = chroma/227.5; ...


3

IIRC, LDIR (et al.) is a 2-byte opcode. The repeat was implemented as a decrement of the PC rather than an increment to the next instruction. Dirt simple, but inefficient on the bus, and not terribly speedy. However, this also had some value, both in the processor implementation and in the system: 1) DRAM refresh was unaffected, as that is done at the ...


2

The manual talks about it being a compiler, but I'm not sure I see significant differences between its I-code and tokenized BASICs in general. Well, so called 'tokenized' BASIC isn't really tokenized, but rather put in a shorthand. Tokenization does require to put everything into token format, which isn't true for average BASICs. The term 'crunched' used by ...


2

I've made a couple of discoveries after a night's sleep. The CoCo still reads the leader length from a RAM address, but its address is two bytes higher in memory than in the Dragon 32: 0199 ** THESE BYTES ARE MOVED DOWN FROM ROM 0200 *** INIT DESCRIPTION 0201 * VALUE 0202 008F CMPMID RMB 1 18 *PV 1200/2400 HERTZ PARTITION 0203 0090 CMP0 RMB 1 24 *PV UPPER ...


2

While I am not familiar with OS9, I did read the linked PDF. As stated in the question's documentation quote, specifying input and output files upon opening the editor is optional. The edit will only be saved automatically if the input and output files have been previously specified. It also appears that only the output file will be modified, with the ...


1

Since the coco cassette interface used 1200 baud psk audio encoding in it, the tape format of the coco was 4X faster loading files from the tape and the tape files were 1/4th the size of similar files on atari and commodore systems, which used 300 baud afsk encoding. it became common to stack multiple files on a single tape. many magazines sold software ...


1

Or alternatively, you could have the awesome CoCoVGA installed in your CoCo2 and hook it up to any VGA monitor. It will add a plethora of colours and other options the original never had! http://cocovga.com/


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