Build your dream computer

Anything relating to non Sinclair computers from the 1980's, 90's or even before.
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PeterJ
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Build your dream computer

Post by PeterJ »

Imagine if you would that you are back in the 1980s and have access to all the home computers of the time. Being an exceptionally gifted individual you can take aspects of any 8bit home computer of the time and build your own. What aspects of what computers would you take?

To get you started...

It would obviously have to be a Sinclair machine, and have the competitive price point.

The excellent BASIC of the Spectrum along with the colour palette and attribute clash.

The keyboard entry choices of the Spectrum 128K

The built in Floppy Disk of the +3

The Sprites and Sound of the C64, but with additional Spectrum BASIC commands.

The build quality and keyboard of the Memotech MTX

The built in SCART Connector of the Sony MSX

The 320 X 200 resolution of the C64 with 16 colours on screen (with 1 background and 1 foreground colour per 8x8 cell)
akeley
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Re: Build your dream computer

Post by akeley »

In short:

Build & looks: CPC 6128
Floppy: Atari 8-bit
Sprites / scrolling: C64
Resolution: Spectrum
Colour palette: Atari 8-bit
Basic: Spectrum
Sound: C64


I guess 320x200 resolution would be superior, but it'd probably also have some limitations so I'm happy to stick with Spectrum's. It seems enough for 8-bit games anyway. 3" floppies were expensive so I'd go with A8 since Commodore's was slow as molasses. And with that, I've just broken my "design" because 6128 looks perfect with 3" bay, big one would spoil it...
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Einar Saukas
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Re: Build your dream computer

Post by Einar Saukas »

The only thing I would change:

viewtopic.php?p=43381#p43381
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TMD2003
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Re: Build your dream computer

Post by TMD2003 »

I must admit I rather liked the way the Amstrad CPC handled its colours when I was looking through the manual not so long ago. The INK command is used as INK a,b where there are four coloured "pens", a is the pen number (1 to 4), and b is the colour from the palette assigned to that pen. So you can flash easily between colours with the same background BBC Micro-style:
PEN 2
PRINT (something)
INK 2,(colour)
(pause)
INK 2,(another colour)
(another pause)
(repeat)

I would at least start with 256 colours the way ULAPlus does - which, if I've got my facts right, is to define each colour thus:
First two bits = blue level (0-3)
Next three bits = green level (0-15)
Last three bits = red level (0-15)
Blue has the least variance in its brightness, so it's the colour that has the least number of levels. This system also gets rid of the need for the BRIGHT channel, and FLASH is more of a hindrance than a help in most cases. Blue 3 and green/red 15 are BRIGHT 1, Blue 2 and green/red 10 are BRIGHT 0, and then there's plenty of scope for darker variations, orange, brown, pink, and the C64's nasty colours. With PAPER and INK for each cell this would double the number of bytes required for the attributes, and I admit I prefer the scope for a 40-column display. And, on top of all this, the most important thing is that it'd allow a decent version of Wizball!

To get 320x240 pixels with 8x8 character squares, (which I think would be better than 320x200, and I'm fairly sure the Amstrad CPC can do 640x480 at high resolution), that's 1200 squares, 8 bytes per square, and 2 bytes per attribute, for a total of 12,000 bytes for the display file.

This new idealised computer will require more memory addresses, so the QL's POKE_L and POKE_W commands will come in very handy.
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RWAC
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Re: Build your dream computer

Post by RWAC »

PeterJ wrote: Wed Sep 16, 2020 10:27 am
It would obviously have to be a Sinclair machine, and have the competitive price point.

The excellent BASIC of the Spectrum along with the colour palette and attribute clash.

The keyboard entry choices of the Spectrum 128K

The built in Floppy Disk of the +3

The Sprites and Sound of the C64, but with additional Spectrum BASIC commands.

The build quality and keyboard of the Memotech MTX

The built in SCART Connector of the Sony MSX

The 320 X 200 resolution of the C64 with 16 colours on screen (with 1 background and 1 foreground colour per 8x8 cell)
I'd prefer a 3 and half inch disk drive.
And 128K BASIC. I really hate having to search for keywords in 48K!
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PeterJ
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Re: Build your dream computer

Post by PeterJ »

[mention]RWAC[/mention],

I agree about the 3.5" floppy, but couldn't think of a home computer in the 80s that came with one.

I didn't say it very well, but I chose 'The keyboard entry choices of the Spectrum 128K' so you could choose an entry type. Best of both worlds and all that.
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Joefish
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Re: Build your dream computer

Post by Joefish »

Here's a bit of uselessness I dreamt of once, and have just now bothered to work it all out.

Instead of the 'BRIGHT' and 'FLASH' bits, what very (technically) simple use could you but those bits to for INK and PAPER? Ideally I'd like it to select an entirely separate and hand-picked alternate set of 8 colours: light grey, dark grey, rich brown, dark mauve, dark green, azure blue, bright orange, light tanned skin. But in reality, on a ULA, what could you achieve?

The Speccy has one bit each for R,G,B, and the BRIGHT bit affects all of R,G,B. But what if you had 2 bits for Green? Or an extra Blue bit? Or even applied it as an extra half-bit to both Blue and Green?

Well, these are all the palettes that result. Assuming the Speccy BRIGHT colours as a starting point (with either 0% or 100% R,G,B), on the left-hand-side are the palettes you get if you have 2 Blue bits, 2 Red bits or 2 Green bits. On the right are if the extra bit affects Blue+Red, Blue+Green or Red+Green. Effectively if either R,G,B is off, and I toggle the half-bit, it raises it to 33.3%. If R,G,B is on, and I toggle the half-bit, it reduces it to 66.7%.

Image

Clearly an extra blue bit does very little for you.

The '2-Green-Bits' palette bottom-left would be a colourful improvement, though it's a bit heavy on the pinks. I think I like the effect of the 'Extra-Cyan-Bit' palette (the one right-middle) most out of these. There's a nice light flesh-tone in there, a nice (magenta-tinted) orange too, although nothing useful as a dark flesh or brown. There aren't any greys, but dark cyan would do...

What do you think? Can you think of another palette you could achieve with some simple logical rules?
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Re: Build your dream computer

Post by Ralf »

Well, if I could use any 8bit computer I would probably use some latest and most advanced one like Sam Coupe or MSX 2.

Sorry Zx Spectrum ;) I would probably want to build something as cool as possible, using standards from 1989, not 1982.

It would have nice resolution and palette. It would have hardware sprites and scrolling. It would have built-in trusty disk drive. And it would have advanced Basic that would allow dealing with sprites and which would allow running games at machine code speed.
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Joefish
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Re: Build your dream computer

Post by Joefish »

Anyway, an ideal 8-bit machine?

Sinclair branding
Oric Atmos shape and colour
Z80 CPU
BBC Basic (and manufacturing quality)
ZX Spectrum 256x192 resolution, but with (a) 16-colour INK/PAPER attributes or (b) four-colour per-pixel, no attributes, or (c):
MSX character-mapped, multicolour character screen mode, and all with...
ZX Spectrum-style in-line video memory map
1/2 palette from the ZX Spectrum (8 BRIGHT colours), 1/2 palette hand-picked from C64 and Amstrad
C64-style hardware pixel scrolling
MSX mono hi-res sprites, but with more on each line like a C64
MSX twin, 2-button joystick ports
Atari paddle port support
C64 light-pen/gun support
MSX cartridge port
C64 sound
128K Spectrum memory paging (but able to page video RAM at 16384 too)
ZX Spectrum expansion port
Last edited by Joefish on Wed Sep 16, 2020 2:43 pm, edited 1 time in total.
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Re: Build your dream computer

Post by AndyC »

TMD2003 wrote: Wed Sep 16, 2020 12:06 pm I must admit I rather liked the way the Amstrad CPC handled its colours when I was looking through the manual not so long ago. The INK command is used as INK a,b where there are four coloured "pens", a is the pen number (1 to 4), and b is the colour from the palette assigned to that pen. So you can flash easily between colours with the same background BBC Micro-style:
PEN 2
PRINT (something)
INK 2,(colour)
(pause)
INK 2,(another colour)
(another pause)
(repeat)
You can flash colours more easily by doing:

PEN 2
PRINT something
INK 2, colour, another colour

You can even vary the speed of flashing with something like SPEED INK, if I remember correctly
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PeterJ
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Re: Build your dream computer

Post by PeterJ »

Joefish wrote: Wed Sep 16, 2020 2:32 pm Anyway, an ideal 8-bit machine?

Sinclair branding
Oric Atmos shape and colour
BBC Basic (and manufacturing quality)
ZX Spectrum 256x192 resolution, but with (a) 16-colour INK/PAPER attributes or (b) four-colour per-pixel, no attributes, or (c):
MSX character-mapped, multicolour character screen mode, and all with...
ZX Spectrum-style in-line video memory map
1/2 palette from the ZX Spectrum (8 BRIGHT colours), 1/2 palette hand-picked from C64 and Amstrad
C64-style hardware pixel scrolling
MSX mono hi-res sprites, but with more on each line like a C64
MSX twin, 2-button joystick ports
Atari paddle port support
C64 light-pen/gun support
MSX cartridge port
C64 sound
128K Spectrum memory paging (but able to page video RAM at 16384 too)
ZX Spectrum expansion port
Excellent! I would certainly buy one [mention]Joefish[/mention]! Although can I have an alternative to the Oric Atmos style case please?
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Re: Build your dream computer

Post by Joefish »

Nope, it's black and blood-orange, or nothing! We're not making N64s here you know.
Tell you what, you can have a range of JCB-Yellow, Grecian-Blue, Transparent-Red and Crystal-Green Quickshot 1 joysticks if you like. With matching colour plugs.
Last edited by Joefish on Wed Sep 16, 2020 3:16 pm, edited 1 time in total.
akeley
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Re: Build your dream computer

Post by akeley »

Image


There truly is no accounting for taste ;)
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Joefish
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Re: Build your dream computer

Post by Joefish »

That thing is gorgeous.
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Re: Build your dream computer

Post by PeterJ »

Image

Apologies if this doesn't make much sense to our non UK friends.
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Einar Saukas
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Re: Build your dream computer

Post by Einar Saukas »

akeley wrote: Wed Sep 16, 2020 3:15 pm Image


There truly is no accounting for taste ;)
It would look even "better" if they painted keys F and J as purple!
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Re: Build your dream computer

Post by TMD2003 »

Here's a 64-colour palette I tried:

In short, it's six bits for INK or PAPER, with two bits left over for... something else that I haven't thought of. The two lowest bits are blue, the next two are red, the highest are green, the way it is on the Spectrum, rather than as it would be for RGB. A value of 1 corresponds to HTML 80, i.e. half intensity; 2 corresponds to HTML C0, which is BRIGHT 0 (on FUSE, at least), and 3 corresponds to HTML FF, which is BRIGHT 1. Hence, there are three levels of brightness for each of the standard seven colours, and plenty more in between...

Image

All it's really missing is brown of some description. Irish and Indian users will celebrate as they can now draw their flag without resorting to defining a UDG from the ZX81's ROM.
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Einar Saukas
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Re: Build your dream computer

Post by Einar Saukas »

TMD2003 wrote: Wed Sep 16, 2020 7:51 pm Here's a 64-colour palette I tried:
[...]
All it's really missing is brown
That's a contradition!
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Re: Build your dream computer

Post by akeley »

TMD2003 wrote: Wed Sep 16, 2020 7:51 pm All it's really missing is brown
It's probably all over at the C64's house...

(Sorry. Will grab my coat now 8-) )
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Re: Build your dream computer

Post by catmeows »

CPU: [email protected]
RAM: 48K ($0000 - $BFFF) + 16K extra page $0000 - $3FFF) for double buffering and few extra KBs
ROM: 2*16KB with mashup of BBC Micro and QL Super Basic

VIDEO: MODE1 Zx Spectrum 256x192 16+16 color attribute, MODE 2 128x192 with 16+16 color atribute and 2 global colors
- that would allow software 2 color sprites over static color background
no hardware acceleration, but with (maskable) raster interrupt on every line

with this palette:
https://drive.google.com/file/d/1K1VszW ... sp=sharing

SOUND: 3 * two 8-bit shift register, each pair forming a channel replaying 8 samples with 4-level resolution. 3rd channel with second mode of xor-shift register to produce noise. that allows square wave with various duty, triangle and saw wave and some other custom waves with rudimentary volume control.
with raster interrupt one could play samples up to 124kHz -> 50 frames, 312 lines, 8 samples in shift register or use more relaxed sample rate and feed shift register only every 2/4/8 lines
(well, that's the cheap solution, the expensive one would be SID)

OUTPUT/INPUT: TV, VIDEO CHROMA+LUMA (S-VIDEO), TAPE, 2xATARI 9PIN ports to connect basicaly anything, MASTER BUS for highend printer/floppy/net

CASE:
This keyboard layout
Image
in this case
Image
with this color scheme
Image

And it should have a sexy tape deck like this (except with standard connectors):
Image

Also it should have Zx Printer done right: https://en.wikipedia.org/wiki/BT100

Cheap plotter Image
Something like Atari Lab https://en.wikipedia.org/wiki/AtariLab (multimeter with probes)
Image

Some cheap NES-like gamepad that would undercut price of contemporary joysticks.

Its target audience would be gamers and geeks in age 6-99.
BASIC would have 32-bit integers and decimal floating point so it could do some serious math.
With quite good keyboard, one should be able to work on his homework or even run small business with floppy and printer attached.

And I would throw some good books on market:
Image
Proud owner of Didaktik M
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Re: Build your dream computer

Post by Joefish »

Maybe better use of the Attribute byte could be 5 bits for INK (2 red, 2 green, 1 blue) and 3 bits for PAPER. So 32 colours (the left and right columns of that 64-colour palette) on 8 backgrounds.

Or 2 blue bits, 2 green and one red. Though I can't think what that palette would be...
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Re: Build your dream computer

Post by 1024MAK »

When talking about better graphics, one thing that often does not get mentioned, is how a Z80 could manage to shift all the data required for a multicoloured high resolution display around. So I’ve wandered if having two Z80s would help. One would run the game play and feed data to a SID like sound chip.

Meanwhile the second Z80, under the direction of the primary Z80, would exclusively handle the graphics. Be it moving sprites around, or scrolling the screen, left/right/up/down...

This idea could even be extended if the video ULA allowed transparency, then the primary Z80 could do sprites while the second Z80 did the scrolling and other video effects.

And much more flexible interrupt timing would allow the programmer to select which TV line start he or she would like an interrupt to fire on ;)

At the very least, 8 bits for the ink colour, 7 bits for the paper colour (1 bit does the transparency). Same resolution and screen layout (but twice the attribute memory area) as the ‘classic’ ZX Spectrum.

A two colour bit mapped high resolution mode: 640 wide mode. Only allowed two colours per video/pixel line, but a two byte palette entry at the start of each line enables each video line to have different colours to those above or below it. This mode allows for 80 column text.

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Re: Build your dream computer

Post by RMartins »

For me I would like something like:

- CPU eZ80
it's an 8 bit CPU fully compatible with Z80, but supports 24 bits addresses (16MB) as a linear memory addressing mode, or the regular 64K mode.
It has an extra 8 bit register, for all the known 16 bit register pairs we know from Z80.
This would avoid any messy bank switching requirements, like we have on 128K or ZXNext

- up to 16 MB RAM

- Sound should have at least 8 channels, with some control for trebble, attack, sustain, the usual stuff for generating good audio.
Interrupt/DMA driven, to feed the music at any rate required.

- Graphics could have the same resolution or go for 320x240 (keep 4/3 ratio)

- Keep 2 color per 8x8 square.

- 32/16 Color palette (4 bits Ink/ 4 bits paper), but allow this palette to be defined, with 6x6x6 or 8x8x8 RGB palette table.
Eventually the same 4 bit color code, could be a different color, if it was used as paper or ink, giving in fact a MAX of 32 simultaneous color system.

- Dual Port memory, to separate video rendering accesses from regular CPU accesses.
Gets rid of contention timings.

- Support programmable interrupts correctly, per device and programmable timer.
Allows to trigger code execution at specific scan lines for example.

- Support a DMA chip.
For faster screen dump/transfers.

- Provide some form of flash drive support
MicroSD memory cards or similar.


Nice things to have:

- An extra processor, independent of the eZ80, for example a Z80 or 6502 for managing sound, blitting, other system tasks, read keys, etc...

- Keyboard controller with interrupts
So that we don't need to scan the keyboard, it notifies us of changes. Could be done, with the extra CPU.

- Simple blitter chip, that could do the usual basic Porter Duff modes (AND/OR/XOR, AKA Masking), while doing transfers (DMA operations), would be nice.

- Have a RTC (Real Time Clock)

- Support WIFI
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Re: Build your dream computer

Post by Stefan123 »

My Spectrum dream computer is already here: the Spectrum Next :) The only thing I would have changed is to let it have a larger keyboard.
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1024MAK
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Re: Build your dream computer

Post by 1024MAK »

Some nice ideas there, but the first post did say that we should be using 1980s technology...

The eZ80 was introduced in 2001. EEPROM / flash memory etc. also is relatively new technology. Same with the FPGA with the Next...

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