What was the most advance 8-bit CPU in the 80's?

whm1974

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OK I first started using computers when I was 9 years old back in 1983, first the Apple II series and TI94, and later the Atari 800XL and C64. I was also given my first computer a Texas Instrument Ti94 for Xmas back then.

Now the 8 bit CPUs most microcomputers used back then used could only address up to 64K(Yes, Kilobytes) without resorting to bank switching and the fastest one was a max of 4Mhz.

Looking back, I'm wondering were there any 8-bit microprocessors that could directly address more then 64K without bank switching and had a FPU available for it, and could do any form of multitasking? Even as prototypes only?
 

whm1974

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Come to think of, I guess a large portion of users here are way too young to remember the 8-bit microcomputer era, or that matter weren't even born yet.
 

SarahKerrigan

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Late-model MSX variants used a Z80 derivative (R800, I believe?) running at above 7MHz with support for a couple MB of RAM. A few other vendors did similar (Hitachi had one with a full-on MMU, for instance.)

6502 and its descendants ended up at 10MHz before the end of the 1980s, and modern 6502's can clock well into the multi-hundred-MHz range.

6800/6809 running OS-9 could get a significant chunk of RAM too, I believe, and - by home computer standards - weren't slow (and, like the 6502 and Z80, are still around today for embedded use.) OS-9 is even still around and used in some embedded designs; I've worked with it. It has not aged especially well, but is still reasonably well-featured.
 

whm1974

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Looking back, I find it to be amazing how small the programs were. After I heard about GEOS back in late 90's/early 2000's, I didn't even know that a GUI was even possible with a 8-bit CPU w/ only 64K of RAM.
 

SarahKerrigan

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Looking back, I find it to be amazing how small the programs were. After I heard about GEOS back in late 90's/early 2000's, I didn't even know that a GUI was even possible with a 8-bit CPU w/ only 64K of RAM.
With enough tricks and hand-optimization, you can get excellent code density. This is critically important to modern embedded systems with limited program space.

Also, I highly recommend looking up ".kkrieger" - a rather pretty (if repetitive) FPS in a 96KB executable.
 
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ozzy702

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With enough tricks and hand-optimization, you can get excellent code density. This is critically important to modern embedded systems with limited program space.

Also, I highly recommend looking up ".kkrieger" - a rather pretty (if repetitive) FPS in a 96KB executable.
Holy cow, that looks amazing considering it's size.
 

whm1974

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With enough tricks and hand-optimization, you can get excellent code density. This is critically important to modern embedded systems with limited program space.

Also, I highly recommend looking up ".kkrieger" - a rather pretty (if repetitive) FPS in a 96KB executable.
Now I'm wondering just how much capability could programmers wring out of the 8-bit systems back then?

Just for giggles, let's throw in an advanced 8-bit CPU with builtin MMU and FPU with an address bus of 20-bits(1 megabyte RAM ) clocked at 10Mhz back then. Also with builtin bank switching hardware support as well.

My my, what could one do with such a CPU if it was available at the time?
 

LightningZ71

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Back when I was programming on that Laser, I could get a surprising amount of performance out of it. I was able to build a 16 color flight simulator that was passable for the era. Electronic arts had a flight sum for experimental planes that included the SR71.
 

whm1974

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Back when I was programming on that Laser, I could get a surprising amount of performance out of it. I was able to build a 16 color flight simulator that was passable for the era. Electronic arts had a flight sum for experimental planes that included the SR71.
I wonder what it would take for an 8-bit system to get good performance with a 256 color 80 column display?
 

LightningZ71

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The 65c02 in my ex2 could be run at 4.77mhz and was fast enough for anything I used it for at the time. That chip could be run at 20mhz in later revisions and the instruction set could be burned to an fpga and run at 200 mhz as well. But it really depends on what you call good performance...
 

moinmoin

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Tuna-Fish

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The most advanced 8-bit CPU you can find is probably some derivative of Z80, designed to add advanced features while remaining compatible with the old code. The problem picking those is that they were contemporaneous with much more advanced 16 or even 32-bit cpus.

The 80's really were the age of 16/32 bit cpus, with Motorola 68k being released in 1979 and Intel 286 being released in 1982. The major home computers in the early 80's used 8-bit cpus because they were very low end, picking the cheapest possible parts to be palatable for consumers. The sensible next step from those is not to the advanced 8-bit chips (largely designed for backwards compatibility with existing customer code bases), but the low end of 16/32 bit cpus.
 

DrRamtop

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Dec 22, 2014
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Looking back, I'm wondering were there any 8-bit microprocessors that could directly address more then 64K without bank switching and had a FPU available for it, and could do any form of multitasking? Even as prototypes only?
The only general purpose '8-bit' processors that could directly address more than 64K without bank switching or an external MMU were usually hybrid 16-bit chips with an 8-bit compatibility mode, like the 65816 with its 6502 mode, or full 16-bit chips with an 8-bit data bus (68008, etc).

As for what's the most advanced 8-bit, it's hard to say. The 6502 and Z80 pretty much kept pace with each other, with clock speeds rising into double digits and both chips acquiring extra hardware like I/O ports, serial UARTS, etc, and both are still in production today in various forms. The 6809 had a lot of fans due to its elegant design, but it never made much of an impact and tends to get overlooked.

Multitasking was possible, but rarely done. Party because the 8-bit chips had no memory protection or privilege levels so one misbehaving program could bring the system down instantly, but mostly because the chips were just so slow and memory so constrained.
 
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DaveSimmons

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The Z80 had a more powerful instruction set than the 6502. The 6502 was much more popular at least in the US thanks to being in the color graphics Commodore and Atari computers vs. the black and white graphics of the TRS-80 model 1. The TRS-80 also had no built in sound output.
 

whm1974

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The most advanced 8-bit CPU you can find is probably some derivative of Z80, designed to add advanced features while remaining compatible with the old code. The problem picking those is that they were contemporaneous with much more advanced 16 or even 32-bit cpus.

The 80's really were the age of 16/32 bit cpus, with Motorola 68k being released in 1979 and Intel 286 being released in 1982. The major home computers in the early 80's used 8-bit cpus because they were very low end, picking the cheapest possible parts to be palatable for consumers. The sensible next step from those is not to the advanced 8-bit chips (largely designed for backwards compatibility with existing customer code bases), but the low end of 16/32 bit cpus.
I didn't use anything but 8-bit systems during the 80's, and in fact didn't even see the IBM PC and its clones other then in a few places until I was around 16(?) after my stepfather brought a 286 based Tandy 1000/TL2 to replace his Atari 800XL which I was still using to write papers for school with Paperclip.
 

DrRamtop

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The Z80 had a more powerful instruction set than the 6502.
It did. The penalty for that was performance, though. The Z80 took a minimum of 4 cycles (one 'T-State') to complete an instruction, which was twice as long as the 6502. On the flip side, it did mean Z80 code could be notably more dense than 6502.

I've build and programmed both Z80 and 6502 systems, and while I prefer the 6502 for coding the Z80 is easier to work with at a hardware level.

The 6502 was much more popular at least in the US thanks to being in the color graphics Commodore and Atari computers vs. the black and white graphics of the TRS-80 model 1. The TRS-80 also had no built in sound output.
Here in the UK (and in much of Europe) it was Z80 systems that dominated. The ZX Spectrum, Amstrad CPC and MSX primarily. The C64 was popular, but no other 6502 system really gained much acceptance. Although the Acorn BBC series sold fairly well in the UK and a few other places, too.

I mostly owned Z80 systems in the 80s; ZX-81, Spectrum + and +2. My only 6502 system was a Commodore Plus/4, which despite its market failure and lack of software is still my favourite 8-bit machine. I have two working Plus/4s right now, as still use them from time to time.
 

whm1974

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OK I'm having silly thoughts about designing a 8-bit ISA and CPU using the lessons and the mistakes we have learn from since the 70's. Is a 1000Mhz(or higher) CPU with 1024 8-bit cores using 4 GB of DDR3 memory really pushing it for a general purpose personal computer with modern features and reasonable performance in this day and age?

I just wonder what one could do with such a PC if it was available and at low cost? Or is this just getting downright silly?
 

whm1974

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No one else is wondering just how far they can push 8-bits? Or is this thread dead now?
 

bbhaag

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If you find the conversation here is coming to a close I would suggest heading over to Vogons. Check out the General Old Hardware forum. I hang out there and it's a friendly place full of people interested and knowledgeable about older hardware. Not to knock this place but it's geared more toward the newer stuff.
 

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