https://sites.google.com/site/zberrysbc/

 

Is it worth it?  Assuredly not, but you can't help but smile if you have any sense of nostalgia.  It also doesn't help that the entire thing can be implemented in an FPGA, although that may actually turn out to be more expensive...

It has been 40 years since?   
 

Quote

Z80 CPU running at 10MHz (20MHz possible)

Amazing clock increase, compared to stock 3.5Mhz 

The first embedded system I was learning to program MCUs on (around 1999) was Atmel's AVR STK500... good times with AT90S1200, AT90S8535...

 

My 1 st Micro computer as it was called then, took up the backseat of a 1966 Olds 442, it was a Altair 8800 kit a picked up at a yard sale in northwest Texas in 1977, I think.  I taught myself tiny basic on this. "writing" (really just copy code from magazines) text games.

2 hours ago, Bubba said:

My 1 st Micro computer as it was called then, took up the backseat of a 1966 Olds 442, it was a Altair 8800 kit a picked up at a yard sale in northwest Texas in 1977, I think.  I taught myself tiny basic on this. "writing" (really just copy code from magazines) text games.

Ah, that 1966 Olds 442 was the car I dreamed of.  Was going to purchase one after I got out of Army, but choose alcohol instead. My first computer was a TI 99/4A, then a used IBM desktop, sometime in the early 70's

13 hours ago, Igor said:

It has been 40 years since?   
 

Amazing clock increase, compared to stock 3.5Mhz 

Never had 512k of ram on my Z80 either. I wonder how they have that set up, given the 64k address space.

Several computers from that time, although their CPU limited to 64K due to 16 bits address bus, use "memory bank switching".

One of the most known example was Apple III, but some others too in the unix word such as Cromemco with as much as 512K

The Z80 was actively used well into the 2000's, the TI calculators used them before the 86/89/92, which changed to Motorola.  The original Game Boy as well had a modified Z80 in it, if I remember correctly.  Most of the later systems used bank switching, the TI-84 has 128 KB RAM alone (Still available I believe)

In any case, were I the guys making that SBC I'd have used the QFP package, unless they figure they'll get smoked easily.

On 6/28/2017 at 6:51 AM, Igor said:

It has been 40 years since?   
 

Amazing clock increase, compared to stock 3.5Mhz 

I think it's even more amazing that the Z80 still sells!!

I've seen Z80 clock frequencies up to 200 MHz (Marvell), so even the 20MHz is quite low.

6 minutes ago, Jens Bauer said:

I've seen Z80 clock frequencies up to 200 MHz (Marvell)

Euuh ?

44 minutes ago, martinayotte said:

Euuh ?

What would you say, if I told you that you can actually purchase a recently manufactured board today, which runs Linux and has a 200MHz Z80 connected directly to a Gbit Ethernet ?

In fact you might soon be able to run Armbian on it. It's the ExpressoBIN.

Yes, yes, it's powered by a Marvell Armada CPU and the Z80 is inside the Topaz switch, but still it's impressive that they use Z80 and not a Cortex-M3 or Cortex-M4 for this (They do use 320MHz Cortex-M3 in some of their SATA controllers, though).

 

-But I really find it impressive that the 10MHz Z80 is still selling today; it's sold at a higher price than a Cortex-M3 (STM32F103) running at 72 MHz - see Farnell or Newark!

Legacy equipment is everywhere, those old 8-bit control systems massively outlived any expectation, and when they fail, unless you have someone from this forum nearby, well...  You find yourself on ebay and Newark buying Z80's at high prices. 

10 hours ago, Jens Bauer said:

has a 200MHz Z80 connected directly

I still don't understand ... How can a 10MHz CPU can be overclocked at 200Mhz ?

If it was a SoftCore in FPGA, I could understand, but it is not the case here, right ?

 

I'm guessing that's the case here.  A lot of the architecture would have to have small tweaks to go that fast, some asynchronous behaviours that can be overlooked at 10 MHz aren't so friendly at 200...

6 hours ago, martinayotte said:

I still don't understand ... How can a 10MHz CPU can be overclocked at 200Mhz ?

If it was a SoftCore in FPGA, I could understand, but it is not the case here, right ?

 

I'm sorry that I've been a little "imprecise".

 

Marvell made a Topaz switch PHY, which is an IC (not a completely assembled device; just the component). Inside the PHY is a bunch of goodies, such as DMA and peripheral controller logic, but they also added a CPU core, ROM and RAM.

The CPU core is using today's technology, which means it can run a lot faster than the the CPUs we had in the 80's.

Eg. smaller circuitry, smaller component = shorter paths, lower voltages = shorter transitions times, etc. All resulting in the thing is being able to be clocked at higher frequencies.

-But remember, since Marvell made their own implementation, they would also be able to optimize the different stages in the CPU.

You could compare it with making your own CPU on an FPGA - or even emulating a CPU on a 4 GHz intel (or even ARM) processor; it would be possible to run the Z80 code much quicker.

-Sadly, if you purchase the Topaz PHY, you can't just start putting your own Z80 code into it, so forget about upgrading your Spectrum.

Ok ! Now, it is much clearer ... (at first, it was sounding like original silicon been overclocked)

 

1 minute ago, Jens Bauer said:

so forget about upgrading your Spectrum

Anyway, back in those days, I was on 6502 ...

4 hours ago, TonyMac32 said:

I'm guessing that's the case here.  A lot of the architecture would have to have small tweaks to go that fast, some asynchronous behaviours that can be overlooked at 10 MHz aren't so friendly at 200...

Spot on.

-But I still wonder why they didn't just put a smaller, more power-saving Cortex-M core inside (they already have the license). The CPU would most likely not be so busy, once it's set up the peripherals.

Existing hardware block perhaps.  I actually have an FPGA I was going to stuff a Z80 soft core into just for kicks. My vhdl is dustier than I want to admit, so that won't be for a while.  

37 minutes ago, TonyMac32 said:

My vhdl is dustier than I want to admit

Mine too, didn't play with FPGA since 18 months.

I've played with ZPUino : https://github.com/alvieboy/ZPUino

and also OldLand CPU from Jamie Iles : https://github.com/jamieiles/oldland-cpu

 

On 6/28/2017 at 8:55 PM, TonyMac32 said:

The Z80 was actively used well into the 2000's, the TI calculators used them before the 86/89/92, which changed to Motorola.  The original Game Boy as well had a modified Z80 in it, if I remember correctly.  Most of the later systems used bank switching, the TI-84 has 128 KB RAM alone (Still available I believe)

I had a TI-83 even before my very first laptop, which makes it the first mobile programmable device I've owned. And I remember in those days I longed for a laptop for a long time, ever since my dad brought home an industrial 286 vga color laptop for a weekend.