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General Category => Off topic => Topic started by: Puresox on 00:05, 13 July 16

Title: How come British Computer developers did not embrace Sprite features?
Post by: Puresox on 00:05, 13 July 16
Not sure what was the best area to put this question, so here it is , for good or ill. Question being why was the British Computer scene not embracing Sprite capabilities into their machines? The US home computers Atari 800(late 70's), Commodore 64(82) had Sprite capabilities and scrolling. Not sure about the Apple 2 and Tandy machines , TI99 etc...


Is this purely an issue to these companies buying power  compared to Sinclair, Acorn,Tangerine and Amstrads , smaller markets and cash flow(And Connections).
Seems strange that at least the Amstrad being 84' machine would not have considered it . Had costs not come down suffice? Or is it more complex an issue?
 .
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: dragon on 01:24, 13 July 16
I think is a simple question about gate array/ula/asic technology.

All briths computers in the begginig depended of the ula ferranti space aviable. As they not search the technology outside u.k.

Others manufacturers. As commodore uses a tecnology from eeuu or japan in case of sega and nintendo consoles.

Simply their technology is more advanced that the ferranti at the time.

Advanced in the sense they have more space aviable in the chip to fit more things.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Docent on 05:20, 13 July 16
Not sure what was the best area to put this question, so here it is , for good or ill. Question being why was the British Computer scene not embracing Sprite capabilities into their machines? The US home computers Atari 800(late 70's), Commodore 64(82) had Sprite capabilities and scrolling. Not sure about the Apple 2 and Tandy machines , TI99 etc...


Is this purely an issue to these companies buying power  compared to Sinclair, Acorn,Tangerine and Amstrads , smaller markets and cash flow(And Connections).
Seems strange that at least the Amstrad being 84' machine would not have considered it . Had costs not come down suffice? Or is it more complex an issue?
 .

It was much cheaper to use off-shelf components and budget was the major constrain.
 I'd also bet on lack of knowledge and technology to design and build such specialized chips - at that time most chips were designed in US and Japan, with production shifting to Far East.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: AMSDOS on 05:30, 13 July 16
Probably because Mr. Sugar wanted to embrace an all-round computer, to handle serious applications as well as the games.
I don't know what would of happened if Amstrad had adopted Hardware Sprites, a C64 for example has 64k, but around 39k is usable, a CPC has 43k (tape based system) or 42k (when disc is introduced), so perhaps Hardware Sprites might of had a compromise on memory back then, which looks bad if you're trying to attract a serious users market as well as a gamers market. The CPC Plusses have Hardware Sprites though, but I've also read that there's a limitation on it.


There is an argument to say why didn't Amstrad get the Firmware right the first time? With clever use of it you can create Sprite like images & it works quite well for @Morri (http://www.cpcwiki.eu/forum/index.php?action=profile;u=95) game "Coolbox".
I started using this approach for my game "Get The Cash" and it was fine in the early versions of the game I wrote in CPC BASIC 3 (http://www.cpcwiki.eu/forum/programming/'get-the-cash'-in-locomotive-basic-cpc-basic-3-and-a-pinch-of-asm/?action=dlattach;attach=18327), but when I started making the game more complicated, it wasn't challenging enough and needed something faster, so I went to Sean McManus' Easi-Sprite Driver, which made a huge difference. You can compare how the game differs by downloading the attached file in Reply #5 (http://www.cpcwiki.eu/forum/programming/'get-the-cash'-in-locomotive-basic-cpc-basic-3-and-a-pinch-of-asm/msg125453/#msg125453) with the file in Reply #6 (http://www.cpcwiki.eu/forum/programming/'get-the-cash'-in-locomotive-basic-cpc-basic-3-and-a-pinch-of-asm/msg126486/#msg126486).
 
In hindsight Hardware coding simply cannot be altered, so there is good examples of Firmware along with bad examples. My game shows that depending on what I wanted to do, the firmware was adequate enough for it, but when I wanted to complicate the process, it needed a software solution rather than a Hardware one. But once the Hardware coding was out there, it's difficult to simply update without causing problems.
The Firmware found in BASIC 1.1 adds onto what BASIC 1.0 has, but when the update was done in Firmware 1.1, some problems emerged for some early 464 programs.  This program (http://www.cpcwiki.eu/forum/programming/basic-programming-tips/msg81806/#msg81806) I wrote, which does a Test on TXT RD CHAR reveals TXT RD CHAR operates slightly differently on a 464 from 6128, so in some of those early games which use TXT RD CHAR, there are problems and programs have to be modified so they can work on all computers, depending on what needs to be done to satisfy this depends on the game. I think some games are more complicated to resolve than others, depends on what the game does, the Dambuster game (http://www.cpcwiki.eu/forum/programming/basic-programming-tips/msg81710/#msg81710) which was harder with BASIC 1.1 (because all the bombs were destroying the Dam Wall), was somewhat easy to resolve with some IF statements.
So in a similar fashion, the CPC Plus adds-onto what the earlier CPCs have, by then all the machines add-onto the later Firmware, the Hardware Sprites no-doubt is seperate from the Firmware, but because it's Hardware like the firmware, limitations came out of it, which makes it difficult to simply replace I presume.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: andycadley on 05:47, 13 July 16
Atari and Commodore were building games consoles which sort of morphed into Computers as that market seemed to be an expanding one whereas the console market was struggling (and would eventually collapse taking many down with it). In Commodore's case, it proved a wise decision allowing them to survive where Atari fell due in part to the lack of success of their home computers and in part to the still heavy dependence on the collapsed console market.

Over in the UK, consoles weren't really a thing until the NES, so we weren't really designing arcade-style chipsets, instead our home computers were all based around much more general purpose hardware.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Puresox on 10:22, 13 July 16
Good overall picture of the situation. Not that I grasped all of it. I conclude that the US market ,pretty much all had there eyes focused on Console being a driving factor, probably at the end of the 70's feelings were starting to sway toward personal home computers (Apple driven?) Atari and Commodore spotted a market for the Masses and focused on all round machine(But heavily games biased due to the energy focused on console stuff) . The US had a lot more access to Computer focused industry ,  Silicone valley, Chips and tech.
 UK obviously everything on lesser scale, but still genius's at the helm to be able to Produced all round machines that ticked boxes , for learning , functionality ,packages for many  uses.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Puresox on 10:30, 13 July 16
Futher question...?


What dictated the colour palette,  Was the  Spectrums grubby, dirty, colours(IMO) picked by someone? LIkewise the C64's Wishy, washy. Pallette was that a considered choice or part of just how things worked?To be fair the C64 could pull off some nice looking stuff. But on the whole ,pretty, Bleached.
 And the Amstrad's forte ,the stunning and opulent ,choice of colours . Was this a master stroke . Or just a fortunate situation?
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: reidrac on 10:38, 13 July 16
Both Atari 800 and C64 were 6502 based machines. I wonder if that was just a coincidence.

Re: palettes, this Wikipedia page has a good explanation and compares different palettes of the time: List of 8-bit computer hardware palettes - Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/List_of_8-bit_computer_hardware_palettes)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 10:48, 13 July 16
Well the 6502 had hardware support for sprites. The Z80 didn't. The BBC, a very british computer, also used the 6502.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: dragon on 11:56, 13 July 16
Well techically amstrad used 6502 at least a few months.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: pelrun on 15:33, 13 July 16
Well the 6502 had hardware support for sprites. The Z80 didn't. The BBC, a very british computer, also used the 6502.


As far as I know that's not at all true. Sprite support has always been supplied by external (to the CPU) hardware; it was just far more prevalent on 6502 systems (maybe because the 6502 wasn't quite as powerful.)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: arnoldemu on 15:38, 13 July 16
Futher question...?


What dictated the colour palette,  Was the  Spectrums grubby, dirty, colours(IMO) picked by someone? LIkewise the C64's Wishy, washy. Pallette was that a considered choice or part of just how things worked?To be fair the C64 could pull off some nice looking stuff. But on the whole ,pretty, Bleached.
 And the Amstrad's forte ,the stunning and opulent ,choice of colours . Was this a master stroke . Or just a fortunate situation?

C64 was chosen.
All you ever wanted to know about the colors of the commodore 64 (http://www.pepto.de/projects/colorvic/)

Speccy and CPC are a product of how it was designed.

Speccy's is ON/OFF with a brightness adjustment.

CPC's is 3 levels of on. (none, "half" and full).

Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: arnoldemu on 15:40, 13 July 16
Not sure what was the best area to put this question, so here it is , for good or ill. Question being why was the British Computer scene not embracing Sprite capabilities into their machines?
I think it depends on the market they wanted to go for.

Sprite capabilities on the c64 is done as part of a custom chipset which is much more expensive to make.

The CPC's and Speccy's custom bits were much less complex and therefore much cheaper to implement.
CPC used other off the shelf chips which was cheaper because it was already done.

TI, MSX and others used the VDP which had sprites. Amstrad chose not to use it.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: arnoldemu on 15:42, 13 July 16
Well the 6502 had hardware support for sprites. The Z80 didn't. The BBC, a very british computer, also used the 6502.

Bryce.
???? No. The choice of CPU doesn't determine if sprites are used or not.

It was down to how much it cost to make the video chip.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: arnoldemu on 15:45, 13 July 16

As far as I know that's not at all true. Sprite support has always been supplied by external (to the CPU) hardware; it was just far more prevalent on 6502 systems (maybe because the 6502 wasn't quite as powerful.)
I disagree. I expect it's the same. Don't forget MSX, Spectravideo, Einstein and others that had VDPs which have sprites.

And the 6502 is comparable to the z80 in terms of power.

Don't compare Mhz. Z80 takes at least 4 cycles for a NOP, 6502 takes a different amount, so you really need to compare real speeds rather than compare Mhz.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 15:56, 13 July 16
I'm no CPU architecture expert, nor do I know the 6502 very well, but I was always believed that the 6502 had features specifically for sprite handling, which the Z80 didn't, but I may be completely wrong. From a hardware point of view I actually grew up with the 6800 and then later the Z80.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: MaV on 17:40, 13 July 16
The second pictures on this site shows a Commodore VIC-II die:
MayhemUK Commodore 64 archive (http://www.mayhem64.co.uk/c64design.htm)
Areas B, E, F, G, H, L, and partly areas I and J are for sprites which is quite a lot of the die area in a time where manufacturing a chip was extremely expensive. Commodore bought MOS and renamed it Commodore Semiconductor Group (CSG), so chip development took place in-house and therefore had the tools to customise their designs and produce cheaper than elsewhere. That gave Commodore somewhat of an edge.

I don't know much about Atari, but they had three custom made chips inside, so they may have been in a likewise situation. The sprite generator seemed a lot less complex than the VIC-II's.


How many video chips with sprite generation were common (and therefore relatively cheap) in the 80s? The 6845 was well-known, as the BBC computers and the IBM PC had it.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 17:48, 13 July 16
The 6845 was made for business computer monitors and was already available in huge quantities back then (due to it being used in so many PC systems), so it would have been a safe and cheap bet for Amstrad.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: reidrac on 17:51, 13 July 16
How many video chips with sprite generation were common (and therefore relatively cheap) in the 80s? The 6845 was well-known, as the BBC computers and the IBM PC had it.

The MSX and the Coleco used the TI TMS9918, and both were Z80 based.

I guess that if the CPC had used something like this, it would have been a very different machine as the TMS9918 is responsible of the MSX and ColecoVision palette (15 colours + transparent).
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: MaV on 18:07, 13 July 16
The MSX and the Coleco used the TI TMS9918, and both were Z80 based.

I guess that if the CPC had used something like this, it would have been a very different machine as the TMS9918 is responsible of the MSX and ColecoVision palette (15 colours + transparent).
A very different machine indeed. We'd be stuck at 256x192 resolution with the 15+1 colours, and no scrolling registers (possible with tricks).

Here's a list of home computers and their video hardware:
List of home computers by video hardware - Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/List_of_home_computers_by_video_hardware)

The second to last column shows their respective sprites capabilities. Unfortunately they lumped the CPC and CPC+ together, so the data is questionable. Nevertheless, it's easily visible that the 8 bit home computers mostly did not have hardware sprites.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: pelrun on 18:48, 13 July 16
Don't compare Mhz. Z80 takes at least 4 cycles for a NOP, 6502 takes a different amount, so you really need to compare real speeds rather than compare Mhz.


I wasn't comparing clock speeds. I was thinking about the small number of registers available on the 6502, although that's offset by the increased number of indirection operators.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: TFM on 21:33, 13 July 16
Well, the CPU is one thing, sprites are a completely other thing. No CPU deals with sprites, for them you need additional chips.

During the 80ies is was simply a question of costs. Usually the lazy hardware guys left it to the coders to compensate the lack of hardware features. Best example: the 8. bit - better to say the missing 8. bit at the CPC's printer port. They sacrificed it for saving the cost of one route on the PCB, so software need to tell the printer "switch 8. bit on / off".

These are all consumer computers, they got made to be sold. Sorry, but that's it.  :-X
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: andycadley on 22:38, 13 July 16

I wasn't comparing clock speeds. I was thinking about the small number of registers available on the 6502, although that's offset by the increased number of indirection operators.
The 6502 design is all about the Zero Page, which gives very fast access to a small amount of memory and used effectively it is like having a large bunch of registers. As a result the 6502 is typically faster even when clocked lower. The Z80 tends to win out in cases where its more "heavyweight" instructions, like block operations and 16-bit math, come into play. Having separate IO space also means you can potentially access a larger amount of RAM without paging since you don't need to memory map hardware devices - although most Z80 machines, including the CPC, do tend to memory map at least some hardware (the video memory) since there is a more restricted set of instructions for working with IO space (and IO space is often only partially decoded to keep hardware cheap)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: dragon on 23:45, 13 July 16
Well, the CPU is one thing, sprites are a completely other thing. No CPU deals with sprites, for them you need additional chips.

During the 80ies is was simply a question of costs. Usually the lazy hardware guys left it to the coders to compensate the lack of hardware features. Best example: the 8. bit - better to say the missing 8. bit at the CPC's printer port. They sacrificed it for saving the cost of one route on the PCB, so software need to tell the printer "switch 8. bit on / off".

These are all consumer computers, they got made to be sold. Sorry, but that's it.  :-X

But in case of amstrad i not sure is cause 100% of cost. Ferranti ula was very bad in terms of lifetime. The need use a hot plate  with a little desing.

More logic gates means,more hot. This can be a problem to the fiability if the ic.


And add alan sugar search made the cpc in a few months

I think probably they want hardware sprites in ant
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Docent on 00:35, 14 July 16

I wasn't comparing clock speeds. I was thinking about the small number of registers available on the 6502, although that's offset by the increased number of indirection operators.

Small number of registers on 6502 doesn't matter because it has the zero page addressing mode, which basically gives you 256 pseudo registers with very fast access to work with. Have a look at this example of loading memory content at 0xa0 into A register for both 6502 and z80:
lda $a0 - takes 2 bytes and 3 cycles
ld a,(#a0) - takes 3 bytes and 13 cycles

While the clock speed of z80 in Amstrad is ~4 times higher than 6502 in C64, C64 will still execute this instruction faster than CPC.
The main difference is the lack of 16bit registers in 6502 - z80 has also better support for 16bit operations and 16bit stack that can be anywhere in the address space. Z80 also has more advanced instructions like ldir, cpir etc. 
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: MaV on 02:11, 14 July 16
lda $a0 - takes 2 bytes and 3 cycles
ld a,(#a0) - takes 3 bytes and 13 cycles
Well, yes. But you are comparing apples to oranges because the Z80 ld a, (adr) uses 16 bit addressing while the 6502 lda $a0 addresses a byte address in zero page. Since the Z80 doesn't have zero page addressing there is no equivalent command. End of discussion.

And the thread is about sprites in hardware and why British computers didn't use them, so please people get back on topic!
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 08:58, 14 July 16
Well, the CPU is one thing, sprites are a completely other thing. No CPU deals with sprites, for them you need additional chips.

During the 80ies is was simply a question of costs. Usually the lazy hardware guys left it to the coders to compensate the lack of hardware features. Best example: the 8. bit - better to say the missing 8. bit at the CPC's printer port. They sacrificed it for saving the cost of one route on the PCB, so software need to tell the printer "switch 8. bit on / off".

These are all consumer computers, they got made to be sold. Sorry, but that's it.  :-X

The hardware limits have nothing to do with laziness. It's more work to do what they did. They were simply designing down to the price they were given, which can be sometimes incredibly difficult to do.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: MacDeath on 10:02, 14 July 16
I always feel the CPC is somewhat a CGA graphic card turned into a computer.

CGA card doesn't have Sprites.


Basically they just aimed at a system with "high resolution" capability, with a decent for its time palette (27 is better than 8 or 15 as on BBC or ORIC or ZXspeccy...), to have those 3 video mode was enough to have a nice choice of colours, and high rez text mode, for cheap.

Also British companies first aimed at home market, so aimed against other britons companies.


And the CPC dev was somewhat rushed with alan sugar always bashing for the less component used possible, lower cost possible (= maximum margin).
They couldn't/wouldn't afford a bigass ASIC as for the PLUS 5-6 years after because the technology wasn't as easy, mastered nor cheap at the time.

When they switched to Z80 during dev, because Locomotive Basic was already designed for Z80, the CP/M compability then became a new aim for the computer.
CP/M computer quite never had Sprites necessity.

Because Graphic user interface with mouse pointer and icons you would move on a desktop or move from one windows into another were NOT the norm... HardSprites weren't really a necessity for small-bizness/serious machines.


Really got lucky CPC turned out to be a not so bad machine after all, and a really well rounded one actually compaired to the pre-1984 market.


Alan Sugar could only figure a box with electronic component able to run softwares for small bizness and perhaps allow youth to learn how to code.
He couldn't know about how the gaming industry would actually become the market powerhouse for home computers, nor he could know about the Demoscene/homebrewgamescene/Chiptunescene which became the powerhouse of the Retrocomputing world 30 years after.

So why put Hardsprites/spriteplan/Blitter/whatever capability ?
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: chinnyhill10 on 10:35, 14 July 16
He couldn't know about how the gaming industry would actually become the market powerhouse for home computers,


Actually he did know. Look at the ratio of serious titles to games on the Amsoft label. He knew you needed lots of games and key serious packages to establish a system.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: fano on 12:44, 14 July 16
Is this purely an issue to these companies buying power  compared to Sinclair, Acorn,Tangerine and Amstrads , smaller markets and cash flow(And Connections).
Seems strange that at least the Amstrad being 84' machine would not have considered it . Had costs not come down suffice? Or is it more complex an issue?
 .
The cost, that's all buddy.Btw , thanks CPC gods to not have specific vdp.They were expensive and CPC is finaly a cheap machine compared to the machines that have dedicaced vdp.
Btw, 80's VDPs had serious limitations (sprite count, colors count, color space/memory constraints, etc...) that makes difficult to do something "out the box" , it is more work to do something "standard" with CPC but you can go further when doing advanced things.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: VincentGR on 17:49, 14 July 16




Sprites have nothing to do with the cpu.
They are fantastic although they have limitations and expensive to build.
I like robocop on Z80 which is a better game as it is slow but I love fast shooters with sprites cause except of the speed, the controls are very responsive on sprites based machines most of the times.
Take an example on Amiga games when you control a sprite or a bob.
As for 6502 vs Z80 most opinions say that they are +/- equal.
Many 3D games run better on ZX/CPC than a C64. There are some exceptions though like stunt car racer which is good on C64 and rescue on fractalus on Atari.
We had a same topic on a Greek site two years ago where I mentioned that 6502 machines had washed palettes ;D  like C64 and NES but what about Ataris?
So it depends on the video chip.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: VincentGR on 17:55, 14 July 16

Sprites have nothing to do with the cpu.
They are fantastic although they have limitations and expensive to build.
I like robocop on Z80 which is a better game as it is slow but I love fast shooters with sprites cause except of the speed, the controls are very responsive on sprites based machines most of the times.
Take an example on Amiga games when you control a sprite or a bob.
As for 6502 vs Z80 most opinions say that they are +/- equal.
Many 3D games run better on ZX/CPC than a C64. There are some exceptions though like stunt car racer which is good on C64 and rescue on fractalus on Atari.
We had a same topic on a Greek site two years ago where I mentioned that 6502 machines had washed palettes ;D  like C64 and NES but what about Ataris?
So it depends on the video chip.

Macdeath : I have the same feeling about the CPC-CGA thing.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: TFM on 18:48, 14 July 16
The hardware limits have nothing to do with laziness. It's more work to do what they did. They were simply designing down to the price they were given, which can be sometimes incredibly difficult to do.

Bryce.


The lack of the 8. printer bit is pure laziness. The lack of FDC-DMA possibilities are pure laziness. The lack of two joystickports with 5 Volt supply are pure laziness. And yes, it's all about saving few pennies here and there. As I told it's a consumer system.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 22:32, 14 July 16

The lack of the 8. printer bit is pure laziness. The lack of FDC-DMA possibilities are pure laziness. The lack of two joystickports with 5 Volt supply are pure laziness. And yes, it's all about saving few pennies here and there. As I told it's a consumer system.

 :picard: The printer port is being driven by an 8 bit latch where all 8 latches are used (D0 to D6 and Strobe). There's no such thing as a 9 bit latch, so including the 8th bit would have required an extra 74LS273 (where only 1/8th of it is being used), plus space on the PCB, plus additional population costs, plus a decoupling capacitor. That's real money, cutting into profits.
Likewise, FDC DMA would have required quite a few more components. Not worth the investment, for a feature that most buyers wouldn't have valued back then anyway.

 These have nothing to do with laziness, they are purely financial decisions.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: TFM on 22:35, 14 July 16
:picard: The printer port is being driven by an 8 bit latch where all 8 latches are used (D0 to D6 and Strobe). There's no such thing as a 9 bit latch, so including the 8th bit would have required an extra 74LS273 (where only 1/8th of it is being used), plus space on the PCB, plus additional population costs, plus a decoupling capacitor. ...


 :picard: :picard2:  Bullcrap! Just connect the PIO and the D7 at the printer port, and voila, there is a full 8 bit port. JUST ONE LINE ON THE PCB. But maybe you have to look up the wikipage about this and make your homework better.
This is getting to stupid for me, und Tschüss!
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Bryce on 22:44, 14 July 16

 :picard: :picard2:  Bullcrap! Just connect the PIO and the D7 at the printer port, and voila, there is a full 8 bit port. JUST ONE LINE ON THE PCB. But maybe you have to look up the wikipage about this and make your homework better.
This is getting to stupid for me, und Tschüss!

That works as a cheap hack, but no respectable electronics designer would patch an unbuffered bit directly to a port in parallel with buffered bits. It may work, but it's an absolute no as far as good design is concerned. And the Amstrads are very well designed.

Bryce.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: 1024MAK on 23:24, 14 July 16
In the 1980's, hardware sprites were a function of special video controller "processor" chips. Whether the CPU was a Z80 or a 6502 or a 6800 or a 6809 or even a 68008 / 68000.

Most UK computer manufacturers wanted to keep the cost low, so expensive special video controller "processor" chips were out of the question due to cost.

Indeed, the Sinclair line (ZX Spectrum and QL) used a general purpose semi-custom ULA for the video system.
The Amstrad CPC used the CRTC 6845 coupled with a custom ("ULA" / ASIC) chip. The Acorn BBC Micro also used a CRTC 6845 coupled with a semi-custom ULA chip. The Acorn Electron used a semi-custom ("ULA") chip that included most of the functions of the video circuitry used in the BBC Micro.

Some UK manufacturers used the TI TMS9918 video processor.

ALso later, the amount of RAM became important, and backwards compatibility was a consideration. So still the cost of expensive special video controller "processor" chips meant they were not often considered.

Yes, let's not have the Z80 vs. 6502 war again. In some applications, one has a slight edge over the other, but in general, they are about the same. The fun part, is they were never designed for use in home computers...! The Z80 was designed for embedded and control applications.

Oh, by the way, neither the Z80 or the 6502 has any special sprite instructions or hardware provisions. But the Z80 does have some useful block copy instructions.

Mark
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: 1024MAK on 23:42, 14 July 16
With regard to printer ports, Amstrad were not the first to only have a 7 bit Centronics printer port. ASCII only needs 7 bits, so you only need a 7 bit port. Well, until it comes to graphic screen dumps and the like....

However, when using a 8 bit latch, I could never understand why one data bit was used for the strobe. It would only cost a couple of extra gates (and some resistors and capacitors) to produce a strobe from the write control used to latch the data in the latch. But of course, if cost was an issue (which it was), then of course, the chip count had to be kept low.

Mark

Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Docent on 23:57, 14 July 16
Well, yes. But you are comparing apples to oranges because the Z80 ld a, (adr) uses 16 bit addressing while the 6502 lda $a0 addresses a byte address in zero page. Since the Z80 doesn't have zero page addressing there is no equivalent command. End of discussion.

You completely missed my point here - obviously they are two different processors with different register set and addressing modes but you can compare timings of a task which is functionally identical on both cpus.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: andycadley on 00:31, 15 July 16
You completely missed my point here - obviously they are two different processors with different register set and addressing modes but you can compare timings of a task which is functionally identical on both cpus.
You can, but those two tasks aren't functionally identical. A closer Z80 equivalent would be LD A,B.

But micro benchmarks are pointless.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: sigh on 00:49, 15 July 16
I always thought it was about the cost. The CPC was that all in one package that also included a monitor, so I'm guessing that adding extra hardware for sprite handling would put it out of whatever price range they were going for. But - I do wonder that when we talk about sprite features, what features are people thinking about? C64 sprite features or something like the MSX sprites maybe? Which of these were cheaper to produce? Though the MSX had the Z80 and sprites*, would you say it benefited from them? Or would you say it didn't?


*This is not to say that a CPC is an MSX without sprites :)




Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: andycadley on 01:09, 15 July 16
There's really a lot more to it than just "cost", though that no doubt plays a part. The C64, for example, has to have a much lower clocked CPU to give the video chipset priority access to the RAM for when it needs to read sprite information. So sprites would almost certainly have meant a slower CPU, or at the very least a more complex memory contention model with some of the RAM being usable for sprites but also slowing down any code accessing it (much like the way memory contention works on the Speccy). Alternatively you can bypass that by moving the sprites into dedicated dual-port memory registers, like the CPC+ does, but that has it's own limitations too.

Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: dragon on 01:45, 15 July 16
You forget  guys, that cpc was developed in a very very litte time, because alan sugar need it ready to the anual product cycle of the company.

Mej works seven days at week at night to make it ready.

Add more circuit maybe simple is not possible with these time. They came out with fails in basic that not was corrected until 664 at cause of that.

Apart  the cost.

They said latter many features of the plus range are the features they thinking to the ant. Only one year later.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: ivarf on 17:53, 15 July 16
That works as a cheap hack, but no respectable electronics designer would patch an unbuffered bit directly to a port in parallel with buffered bits. It may work, but it's an absolute no as far as good design is concerned. And the Amstrads are very well designed.

Bryce.
Sounds like something Sinclair's engineers would do to save money
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: ivarf on 17:59, 15 July 16
1. Think about how little time they had to construct the CPC as the first teams miserable fail.
2. Cost
3. Experience, the designers had only made business and mini computers earlier.

Still I believe having read that sprites was planned but they run out of time
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: sigh on 18:27, 15 July 16
1. Think about how little time they had to construct the CPC as the first teams miserable fail.
2. Cost
3. Experience, the designers had only made business and mini computers earlier.

Still I believe having read that sprites was planned but they run out of time

Do you remember where your read this?

There's really a lot more to it than just "cost", though that no doubt plays a part. The C64, for example, has to have a much lower clocked CPU to give the video chipset priority access to the RAM for when it needs to read sprite information. So sprites would almost certainly have meant a slower CPU, or at the very least a more complex memory contention model with some of the RAM being usable for sprites but also slowing down any code accessing it (much like the way memory contention works on the Speccy). Alternatively you can bypass that by moving the sprites into dedicated dual-port memory registers, like the CPC+ does, but that has it's own limitations too.




But wouldn't all this depend on the sort of sprite hardware chip used? The chips used in the MSX - does it have the problems you mentioned?
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: 1024MAK on 18:54, 15 July 16
But wouldn't all this depend on the sort of sprite hardware chip used? The chips used in the MSX - does it have the problems you mentioned?
The chip used in the MSX is the TI TMS9918A video processor. The TMS9918A did have hardware sprites, but was limited to 16k bytes of video RAM, it did not produce RGB video (it only produced signals suitable for 60Hz NTSC composite video) and it had a limited resolution screen (text modes: 40 × 24 and 32 × 24, graphics: 256 × 192, 15 colours + transparent).

The version for 50Hz video was the TMS9929A, it was the same as the TMS9918A but produced Y, R-Y and B-Y signals (luminance and colour difference signals) suitable for sending to a PAL colour encoder, which then produced a PAL composite video output.

The subsequent MSX2 and MSX2+ machines used video processors that were developments of the TMS9918A, with much expanded specs.

The Wikipedia page for the TMS9918A is here (https://en.wikipedia.org/wiki/Texas_Instruments_TMS9918).

Mark
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: andycadley on 19:46, 15 July 16
But wouldn't all this depend on the sort of sprite hardware chip used? The chips used in the MSX - does it have the problems you mentioned?
The chips in the MSX use RAM that isn't directly accessible by the main CPU, so you avoid the contention problem but make it harder (and slower) to make changes to the display (which is one of the reasons a lot of MSX games play like slow versions of Speccy game)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: TFM on 19:50, 15 July 16
That works as a cheap hack, but no respectable electronics designer would patch an unbuffered bit directly to a port in parallel with buffered bits. It may work, but it's an absolute no as far as good design is concerned. And the Amstrads are very well designed.

The absolute same(!!!) pin of the PIO is already directly connected to the data write port of the tape port. If it's ok for the tape port, then it's ok for the printer port too.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: ivarf on 20:03, 15 July 16
Do you remember where your read this? (Sprites planned for the original CPC)

I am not sure, but either comp.sys.amstrad.8bit or in the story of how the CPC was created that ran over 3-4 issues of Amstrad User. Cliff Lawson, Locomotive Software and Roland Perry frequented comp.sys.amstrad.8bit in mid 90s.

Or maybe here?
You’re NOT fired: The story of Amstrad’s amazing CPC 464 • The Register (http://www.theregister.co.uk/2014/02/12/archaeologic_amstrad_cpc_464/)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: ivarf on 20:27, 15 July 16
A bit off-topic, but I see that Cliff Lawson stayed with Alan Sugar until 2011. He started in 1984, so that's 26-27 years. A long Amstrad career...
https://uk.linkedin.com/in/cliff-lawson-86471b2a (https://uk.linkedin.com/in/cliff-lawson-86471b2a)
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: sigh on 22:59, 15 July 16
The chips in the MSX use RAM that isn't directly accessible by the main CPU, so you avoid the contention problem but make it harder (and slower) to make changes to the display (which is one of the reasons a lot of MSX games play like slow versions of Speccy game)

The slow games were mostly from the spectrum ports. The games made with the MSX specs in mind (Aleste, Space Manbow, Ikari Warriors etc) play fast and smooth.
Would love to get my hands on one of these.

Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: Puresox on 15:19, 16 July 16
The issue about STunt Car Racer , I imagine it was designed for the C64 then converted to Speccy, Amstrad? I can't see why it should be faster on the C64.


Amstrad games designed with the Amstrad in mind could run fast and smooth . When it was converted from Speccy designed games that is where it suffered . Just like the MSX .
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: fano on 13:47, 17 July 16
The issue about STunt Car Racer , I imagine it was designed for the C64 then converted to Speccy, Amstrad? I can't see why it should be faster on the C64.
Clearly because it has been well designed on C64 , drawing road is 2 bits per pixel so half of the data amount for a CPC and they seem to have used hardware sprites for the car.



Btw, you're right, on any machine rendering engine needs to be designed especially for target if you want to get  the best possible result.If the game design fits perfectly with machine limitations, that's better too.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: VincentGR on 17:04, 17 July 16
on any machine rendering engine needs to be designed especially for target if you want to get  the best possible result.If the game design fits perfectly with machine limitations, that's better too.


True. Same happened to all machines back then and for the 3D games on 16bit era.
Most of them are ports from the ST and Amiga runs at lower speeds due -1MHz.
They could use the blitter for line drawing and filling.
Title: Re: How come British Computer developers did not embrace Sprite features?
Post by: ivarf on 11:13, 24 July 16
The issue about STunt Car Racer , I imagine it was designed for the C64 then converted to Speccy, Amstrad? I can't see why it should be faster on the C64.


Amstrad games designed with the Amstrad in mind could run fast and smooth . When it was converted from Speccy designed games that is where it suffered . Just like the MSX .

I think the C64 version was coded by Geoff Crammond himself. He knew the processor well from all his BBC games. Maybe he made an original and much faster BBC version that never got published? The BBC was 2 MHz, the C64 only 1 MHz