Author Topic: The best 8 bit home computer?  (Read 5622 times)

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Offline ivarf

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Re: The best 8 bit home computer?
« Reply #50 on: 13:55, 15 January 17 »
I read it somewhere, maybe Amstrad User or Amstrad Action

Offline PulkoMandy

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Re: The best 8 bit home computer?
« Reply #51 on: 11:39, 16 January 17 »
Mode R uses interlace which is unstable with CPC.


This is not true anymore.


Grimmy studied in details the video circuits and found a way to generate a proper interlace signal. The trick involves generating a 32us line from the CRTC with an HSync at the end of it, at the start of odd fields, and at the end of even ones. With this the interlace works perfectly. There are at least two demo pictures from Grim using this, and some from Dadman which I think were never released.


Picture using interlace: https://demozoo.org/graphics/98498/

Offline Skunkfish

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Re: The best 8 bit home computer?
« Reply #52 on: 13:29, 19 January 17 »
Did you miss the link above?
http://plus4world.powweb.com/software/VDC_Challenge
I can also point to my old demo -

Impressive stuff. I don't know much about the Plus 4, other than I remember briefly playing on one around a friends house back in around 1990 (I think the game was Back to the future III). Just looking at the palette on Wikipedia, it looks like it's missing a true red? Is that right?

Offline Bryce

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Re: The best 8 bit home computer?
« Reply #53 on: 13:45, 19 January 17 »
I've a Plus/4. Great little computer and the best looking Commodore in my opinion.

Bryce.

Offline ivarf

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Re: The best 8 bit home computer?
« Reply #54 on: 14:12, 19 January 17 »

Is that actually true?

Below is some information from the Plus/4 Wikipedia. It doesn't confirm the story, but it confirms Commodores planned naming of the 264 and 364 and the release date of the 264 which by then had its name changed to plus/4. It was released at the same time as the Amstrad CPC 464. See below:


"Rumors spread in late 1983 of a new computer in 1984 called the "Commodore 444" or "Ted", with built-in word processing and spreadsheet software, and that it would be one of four new computers that would replace the VIC-20 and 64, which the company would discontinue.[4][5] The company's third salvo – which, as it turned out, was fired just as most of Commodore's competition was leaving the home computer market – was the C116, C16, and 264, which became the Plus/4. There were also prototypes of a 232, basically a 32 KB version of the Plus/4 without the software ROMs, and a V364 which had a numeric keypad and built-in voice synthesis. The latter two models never made it to production."

"The Plus/4 was introduced in June 1984 and priced at US$299 (equivalent to $689.27 in 2016). It was discontinued in 1985. "

Offline ivarf

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Re: The best 8 bit home computer?
« Reply #55 on: 14:22, 19 January 17 »
I have made a list of 8 bit home computers which are the best (IMHO) with some feature.

BBC Micro and Commodore 128 VDC - the best speed of calculation with screen on
Commodore +4/PAL - the best speed of calculation with screen off
I assume you mean in machine code and not Basic. The BBC surely is faster than the Commodore machines when calculating in Basic.

What makes you say that plus/4 is faster than the Commodore 128 and BBC with the screen off? I know that the processor is seriously slowed down with the screen on for the plus/4, almost to the level of the C64! But with the screen off you it's faster, I can only assume that the 1.76MHz 8501 is more effective than the 2 MHz 6502s used in the other two machines? Or is there other architectural problems that hold them back?

Offline litwr

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Re: The best 8 bit home computer?
« Reply #56 on: 17:58, 29 January 17 »
What makes you say that plus/4 is faster than the Commodore 128 and BBC with the screen off? I know that the processor is seriously slowed down with the screen on for the plus/4, almost to the level of the C64! But with the screen off you it's faster, I can only assume that the 1.76MHz 8501 is more effective than the 2 MHz 6502s used in the other two machines? Or is there other architectural problems that hold them back?
Commodore+4 has a bit to toggle between PAL and NTSC modes.  So C+4/PAL with this bit switched to NTSC has 25% speed boost.  Its 6502 works at 2.21 MHz at this mode.  See http://litwr2.atspace.eu/pi/pi-spigot-benchmark.html for a proof.  I may also give a link to another demo - http://plus4world.powweb.com/software/HNY2013 - a moving picture is drawn by CPU only.
Commodore Basic for +4/128 is slow but it gives more memory and functions than Amstrad CPC Basic.  BBC Micro has an excellent Basic but the fastest is Mallard Basic for Amstrad PCW.

Offline ivarf

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Re: The best 8 bit home computer?
« Reply #57 on: 22:46, 29 January 17 »
Commodore Basic for +4/128 is slow but it gives more memory and functions than Amstrad CPC Basic.  BBC Micro has an excellent Basic but the fastest is Mallard Basic for Amstrad PCW.
I think both of these Amstrad Basics have its origins on the BBC...

Offline ZbyniuR

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Re: The best 8 bit home computer?
« Reply #58 on: 19:07, 06 November 17 »
Recently a read this topic, and I think some of you know quite a little about some platforms, especial XL/XE.
So I gave you some links. :)

http://g2f.atari8.info/gallery_hires/index.html  - Atari's like MODE 1 - withaut tricks just 2 shade of the same color.
 http://g2f.atari8.info/gallery/index.html         - Atari's like MODE 0 - with tricks could be 5 or 6-bits per pixel, and overscan.


https://www.youtube.com/watch?v=40CPFljl3fk   - Diamond GUI for Atari 8b from 1989, cartridge version only.

https://www.youtube.com/watch?v=VIDD306aYhQ  - 60 old Atari's games in 5 minutes. Most best newest missed.

http://www.colodore.com  - How is change palette in C64 (Vic-II) and C+4 (TED) when you tuning saturate.

jesusarnold - it's channel with few 100 games in 10 min. films. I like Sega Master and NES. ;)

https://www.youtube.com/watch?v=y2EqX3rpJ6M&list=UU4CuqbDUPaa7WcM4jGoeafQ&index=24
 - CPC for example above, and  SMS here -> 
https://www.youtube.com/watch?v=CmMCmZkXrMQ

MSX2 -
https://www.youtube.com/watch?v=usMQho6FrcA - 40 min. Sorry, I can't find something shorter.

If you want more similar link, let me know. :)
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Offline ThomH

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Re: The best 8 bit home computer?
« Reply #59 on: 23:34, 17 November 17 »
Have anyone seen sales numbers for the Sam Coupe, MSX2 and Amstrad plus/GX4000. I assume the first and only batch of Amstrad pluses/GX with were several hundredthousands machines.
As the thread has been revived anyway: I was a Sam owner back in the day and the number I have seen most often for it is just 13,000 machines produced, quite possibly all by MGT. Different people have different opinions as to whether SamCo manufactured only, but West Coast Computers' were definitely just cheaply-modified unsold stock.

I think the main issue with the Sam Coupe is the shared memory pool.
Same as the CPC but it was more severe on the Sam resulting in an effective CPU speed of only 14% faster than the speccy.
Also considering that the Sam had to push more pixels than the speccy, that percentage went down even further.
Same number of pixels as a Spectrum (except in its Mode 3), but at four bits per pixel rather than 1.125. Absolutely crippled by memory contention though, as you say: that's 128 bytes for the pixel area in the main two modes, with the active area being about 2/3rds of the display. So the display requires exactly 50% more memory bandwidth than does the CPC's.

The same rule as the CPC applies anywhere that pixels are not on display: the CPU may make one memory access every four cycles. Where pixels are on display, it may make an access only once every eight cycles.

Mode 1 is the Spectrum-compatible mode, and slows things down even further by applying the once-in-eight penalty approximately half the time even while pixels aren't being fetched. Mode 2 is a Spectrum-esque mode but pixels are linear and attributes apply to 8x1 regions. There is no additional slowdown.

Ordinarily the pixel portion of the display is 192 lines high out of 311, so pixels in general are being output close to 41% of the time.

Assuming everything's being run in RAM, that the display is normal, and that memory accesses are the limiting factor then, given the nominal CPU clock speed of 6Mhz, for almost 59% of the display the processor is running about 150% as fast as a CPC. For the other 41% it's running about 75% as fast.

So I make that about 20% faster than a CPC. But with a fixed 24kb frame buffer, and no hope of getting hardware help at all. Picking which 32kb page it falls in is the limit of your ability to pick video modes and it is not believed that there is any way to trick the ASIC into deferring its work.

In net: think of the best software scroll you've seen on a CPC and imagine it being about 25% slower.

There are per-line interrupts and you can disable the display entirely and get that processing time back so it's possible to create a shorter display but it's not common because the display is already quite wide compared to its height: pixels are about 125% as wide as tall, so the aspect ratio with all pixels allowed is approximately 5:3.
« Last Edit: 23:36, 17 November 17 by ThomH »

Offline ivarf

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Re: The best 8 bit home computer?
« Reply #60 on: 00:18, 18 November 17 »
As the thread has been revived anyway: I was a Sam owner back in the day and the number I have seen most often for it is just 13,000 machines produced, quite possibly all by MGT. Different people have different opinions as to whether SamCo manufactured only, but West Coast Computers' were definitely just cheaply-modified unsold stock.


In net: think of the best software scroll you've seen on a CPC and imagine it being about 25% slower.


Interesting post. I have found the number for the GX4000, its about the same as the Sam, 15 000.


Which CPC game has the best softwarescroll, biggest, smoothest? Anyone?

Offline tjohnson

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Re: The best 8 bit home computer?
« Reply #61 on: 09:45, 18 November 17 »

Interesting post. I have found the number for the GX4000, its about the same as the Sam, 15 000.


Which CPC game has the best softwarescroll, biggest, smoothest? Anyone?
Think that's been asked a number of times and the are some threads about it.  Tornado low level ttl has good scrolling.

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Offline GUNHED

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Re: The best 8 bit home computer?
« Reply #62 on: 17:39, 19 November 17 »
I have made a list of 8 bit home computers which are the best (IMHO) with some feature.


Maybe it would be a great idea to add a poll here.  :)