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

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whm1974

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Jul 24, 2016
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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.
Thanks, I'll do that. I'm wondering just what one could do with an modern 8-bit CPU with a well thought out ISA and has more then 8 registers like 16 or 32
 

bbhaag

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Jul 2, 2011
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I don't have an answer to that question but I bet some of the guys over at Vogons do. I'm a 16-bit guy myself. The 386 and 486 cpus interest me the most. Honestly your question is beyond my knowledge on the subject.
 

Markfw

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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?
Not exactly answering your questions, but.... The first computer I programmed was a Tektronix 4051. It has 16K of memory, and read the program from an internal tape drive. So the program would load the first track (could not be more than 16k in memory) and than when that section was complete, you programmed it to find the second track and load 16k more, and go on. Until the tape was done (300k total)

And BTW, those 4051 computer were all over the bridge in the Movie/TV series "Battlestar Galactica", that is the original series, not the remake. (circa late 70's and early 80's)
 
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whm1974

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Not exactly answering your questions, but.... The first computer I programmed was a Tektronix 4051. It has 16K of memory, and read the program from an internal tape drive. So the program would load the first track (could not be more than 16k in memory) and than when that section was complete, you programmed it to find the second track and load 16k more, and go on. Until the tape was done (300k total)

And BTW, those 4051 computer were all over the bridge in the Movie/TV series "Battlestar Galactica", that is the original series, not the remake.
Good grief I remembered quite well just how slow cassette tapes were. Back in '82 or '83, my mother and I moved in with her boyfriend and he had an Atari 800XL. He had both the floppy and tape drives. The games he had on cassette could take as long as 30 minutes, maybe even more to load.
 

Markfw

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Good grief I remembered quite well just how slow cassette tapes were. Back in '82 or '83, my mother and I moved in with her boyfriend and he had an Atari 800XL. He had both the floppy and tape drives. The games he had on cassette could take as long as 30 minutes, maybe even more to load.
no, no , no, these were computer tape drives, nothing like cassettes. Metal backplanes, and slower still than even cassettes
 

Oyeve

Lifer
Oct 18, 1999
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My earliest comp experience was with a most technology 6502 based Atari 400. Still have it along with an Atari 800XL. Need an RF connector to hook up to my 4k TV.
 

scannall

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Jan 1, 2012
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The first computer I used on a daily basis was a PDP 11/70. Punch card hell. The first computer of my own was an Apple ][+. Loved that little thing. What a great machine for the time.
 
May 11, 2008
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Thanks, I'll do that. I'm wondering just what one could do with an modern 8-bit CPU with a well thought out ISA and has more then 8 registers like 16 or 32
I do not know if you have any experience with these microcontrollers, they are 8 bit models : pic processors from microchip or AVR from Atmel ?
About a year or something ago, atmel was bought by microchip :
Fun fact is that the pic architecture was available in 1976.
AVR in 1996.

http://www.microchip.com/

http://www.atmel.com/products/microcontrollers/avr/default.aspx

Both these architectures are very fast.
AVR has 32 registers and is a load store architecture.
PIC has an architecture that sees the ram (register file) as registers.
The ram is banked for speed puposes.
But modern pics allow linear addressing as well and rapid access through bank switching register files.

Here are nice wikis :

https://en.wikipedia.org/wiki/Atmel_AVR
https://en.wikipedia.org/wiki/Atmel_AVR_instruction_set

https://en.wikipedia.org/wiki/PIC_microcontroller
 
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whm1974

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Jul 24, 2016
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I do not know if you have any experience with these microcontrollers, they are 8 bit models : pic processors from microchip or AVR from Atmel ?
About a year or something ago, atmel was bought by microchip :
Fun fact is that the pic architecture was available in 1976.

http://www.microchip.com/

http://www.atmel.com/products/microcontrollers/avr/default.aspx

Both these architectures are very fast.
AVR has 32 registers and is a load store architecture.
PIC has an architecture that sees the ram (register file) as registers.
The ram is banked for speed puposes.
But modern pics allow linear addressing as well and rapid access through bank switching register files.

Here are nice wikis :

https://en.wikipedia.org/wiki/Atmel_AVR
https://en.wikipedia.org/wiki/Atmel_AVR_instruction_set

https://en.wikipedia.org/wiki/PIC_microcontroller
I have never messed with microcontrollers before. And is the difference between those and a CPU?
 
May 11, 2008
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I have never messed with microcontrollers before. And is the difference between those and a CPU?
Well, a microcontroller generally has hardware on board like timers, analog to digital converters and serial ports alike uarts (rs232) or SPI and I2C(also known as TWI) (two common serial formats used very much in the electronic chips) world to connect chips with different functionality together. Microcontrollers embed program memory like rom or eeprom or flash, ram and peripherals in a single ic package.
Microcontrollers generally lack the ability to add more ram or flash although there exist enough versions that allow expansion of ram and even flash through an external data and address bus. But these are usually pretty large in size and amounts of pins.

If you want to know what a single PIC16F628 can do.
2048 14 bit words of program memory
and 224 bytes of ram.
maximum 20MHz @ 200ns instruction cycle.
All pics are pipelined and almost all instructions are single instruction cycle (4 clocks).
As a sidenote, the AVR also has allmost all single cycle(single clock cycle) instructions and has a pipelined architecture.

Here is a space invaders game in color on youtube :
 
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May 11, 2008
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I forgot to note, that the pic does not have any hardware onboard to output an analog videosignal and connect to a television set.
All is emulated by gifted programmers that make smart use of the hardware like timers and instructions and instruction timing of the pic.
No blitters , sprite control or collision detection in hardware.
 

sdifox

No Lifer
Sep 30, 2005
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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?
https://en.wikipedia.org/wiki/Intel_8086
https://en.wikipedia.org/wiki/Intel_8087

8086 can address 1MB
 

Markfw

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Update to my proevious post. I used a 4052, which I did not realize was way different than the 4051 that uses a Motorola 6800 chip. The 4052 uses AMD chips ?????? See this text(link:https://en.wikipedia.org/wiki/Tektronix_4050):

The second model was the 4052, which in spite of the similar name was a very different system. This had a CPU based on four AMD 2901 4-bit bit-slice processors used together to make a single 16-bit processor. It could also be used in a 6800-compatible mode, allowing it to run software from the 4051, although it did so much faster than the original 4051. Released in 1978, it came with a full 32 kB of RAM for $9,795, and could be expanded to 64 kB for another $1,995. The 4054 was a version of the 4052 built around the 19" screen from the 4014 terminal rather than the 11" screen from the 4012, increasing resolution to 4,096 by 3,072.

External storage units were available for the 405x series computers. The 4924 was an external version of the internal DC300 tape drive. The 4907 used single or dual Shugart 851R 8 inch floppy drives with 64 kB floppies and the larger, 2-drawer filing cabinet sized, 4909 storage unit used a CDC 96 megabyte hard drive with the first 16 megabytes in the form of a removable disc-pack. Two sizes of the 4956 graphics tablet offered a slow process for inputing from paper drawings. The 4952 joystick was used for graphics input.

Because the direct view storage tubes do not flicker as do conventional CRTs, and because the BASIC programming interface allowed simple, rapid rendering of vector graphic displays, the 405x series were used in many theatrical contexts. In particular, 405x computers can frequently be seen in early Battlestar Galactica sets.
 

sdifox

No Lifer
Sep 30, 2005
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Yes but the Intel 8086 is a 16-bit CPU with a 20-bit address space. I'm asking if there was an 8-bit CPU with a 20-bit address space or even larger back during the 80's.

Doubt it. Memory was expensive and took a lot of real estate since they were on sockets.
 

DrRamtop

Junior Member
Dec 22, 2014
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Yes but the Intel 8086 is a 16-bit CPU with a 20-bit address space. I'm asking if there was an 8-bit CPU with a 20-bit address space or even larger back during the 80's.
I don't pretend to know every 8-bit processor, but certainly none from the major manufacturers had anything more than a 16-bit address bus. The thing that gets forgotten these days is that all the main 8-bit architectures were designed in early or mid 70s, when personal computers were still a few years away. The designers built their processors for industrial use, where 64K was far more than enough memory, especially given the high cost of DRAM at the time. MOS, Zilog and Intel (and I'm sure others, too) built versions of their processors with a very small amount of on-chip RAM (usually 256 bytes or so) because many industrial uses didn't require any more than that.

Another thing that gets overlooked is the limitation imposed by packaging technology. The only cheap package for processors back then was the dual in-line package (DIL), which maxed out at around 40 pins. Squeezing a 16-bit address bus, 8-bit data bus, and all the associated power and control lines into 40 pins was hard enough. Extending the address bus would mean moving to a much more expensive package, or multiplexing the buses, which required lots of external decode logic and a whole new set of peripheral chips.
 
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whm1974

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I don't pretend to know every 8-bit processor, but certainly none from the major manufacturers had anything more than a 16-bit address bus. The thing that gets forgotten these days is that all the main 8-bit architectures were designed in early or mid 70s, when personal computers were still a few years away. The designers built their processors for industrial use, where 64K was far more than enough memory, especially given the high cost of DRAM at the time. MOS, Zilog and Intel (and I'm sure others, too) built versions of their processors with a very small amount of on-chip RAM (usually 256 bytes or so) because many industrial uses didn't require any more than that.

Another thing that gets overlooked is the limitation imposed by packaging technology. The only cheap package for processors back then was the dual in-line package (DIL), which maxed out at around 40 pins. Squeezing a 16-bit address bus, 8-bit data bus, and all the associated power and control lines into 40 pins was hard enough. Extending the address bus would mean moving to a much more expensive package, or multiplexing the buses, which required lots of external decode logic and a whole new set of peripheral chips.
I'm sure with usingmodern processes and designs we could produced a high powered 8-bit CPU at reasonable cost.
 

Ichinisan

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Oct 9, 2002
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[edit]

Derp! I was thinking of 16 bit.

11111111 = 256 (8 bit)
1111111111111111 = 65,535 (16 bit, 64k)

Normally, "8-bit" means literally 8 electrical traces the CPU can use to address RAM. "11111111" is 256 --so an "8-bit" memory bus cannot address more than 256 bytes without memory map bank-switching trickery.
 
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NTMBK

Diamond Member
Nov 14, 2011
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Normally, "8-bit" means literally 8 electrical traces it can use to address RAM. "11111111" is 65,535 (64k) --so an "8-bit" CPU cannot address more than 64k. If an "8-bit" CPU addresses more than that, it's either it's doing some bank switching stuff, or it's not truly an "8-bit" CPU.
Who taught you binary? :p (2 ^ 8 - 1) is 255.
 

whm1974

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For what purpose?
For any purpose. Get a bunch of Homebrewers together and challenge them to build a personal computer with modern features around it.

And yes the homebrew computer scene is still a thing.
 

DrRamtop

Junior Member
Dec 22, 2014
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I'm sure with usingmodern processes and designs we could produced a high powered 8-bit CPU at reasonable cost.
We already do. They're just called microcontrollers now, as they contain a bunch of useful stuff alongside the 8-bit CPU core. Atmel makes a whole range of them. They have general purpose programmable I/O pins rather then fixed-function address or data buses, but you can certainly hook the more advanced ones up to an EEPROM and some RAM and use them like an old-school 8-bit CPU.
 

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