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Comment by tverbeure | Hacker News Reader

For those interested in hacking in this:

The Pano G2 FPGA is a monster, but prices on eBay have gone up a lot. My cheapest buy was 25 of them for $85 (including shipping!). They now go for around 1 for $30 if you’re lucky... or $200+ for many.

The Pano G1 (with VGA instead of DVI) is cheaper but has a much smaller FPGA, though still large by hobby standards.

The benefit of the G1 is that all interfaces are working now, including DRAM, USB, Ethernet.

Last week, Skip Hansen got a full CP/M system running on one: https://github.com/skiphansen/pano_z80

USB on the G2 is hard. A bunch of people have tried and failed.

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OP here - just a note, that "tverbeure" is the Tom I mention in my blog post.

None of this would have been possible without you, Tom! Thanks for everything.

Well you two owe me $32 :-). Kidding of course but the G2 looks like a cool gizmo and so I got one.

I'm wondering if my Scarab code for the LX6+ will move over.

What's the Scarab and LX6+? The closest I'm finding is an ESP32 beetle which has a Tensilica LX6 processor.

My bad, it is this one: https://www.scarabhardware.com/minispartan6/

I built a frame buffer for a Cortex-M4 on it.

I never was a fan of the Zilog Z80 (its instruction set reminded me too much of the idiotic intel 80x86 family), but seeing someone running the Control Program for Microcomputers on a whopping 25 MHz Z80 is incredibly cool... just imagine what kind of scene demos could be coded on this monster for the next demo party...

I wonder if it would be possible to retrofit an MMU onto a Z80 design and port a real UNIX to it? 25 or even 50 or even a 75 MHz UNIX server on a Z80 processor, that'd be a nice perversion...

This guy ran Linux on an ARM emulator on an ATmega. A similar feat should be possible on a Z80.

http://dmitry.gr/?r=05.Projects&proj=07.%20Linux%20on%208bit

I remember that. That was emulation and it was not usable the way a 75 MHz Z80 could be, running code directly on the CPU (even if it is an FPGA).

> [the Z80's] instruction set reminded me too much of the idiotic intel 80x86 family

That is because the z80 was a (mostly) binary compatible superset of the 8080 instruction set, and the 8086 (while not binary compatible) was intentionally modeled after the 8080 such that there was a program that could take an 8080 program and do the 1:1 instruction mapping from 8080 to 8086 and get a working 8086 program.

> I wonder if it would be possible to retrofit an MMU onto a Z80 design

Zilog made a number of Z80 follow-on CPUs, and some have MMUs. It is amazing how far they took the instruction set; the Z80380 could run Z80 code as-is, but it also extended instructions to support 32b operations and had a mode with a flat 32b linear address space. I don't recall ever hearing any consumer product using it though.

Z80380 user’s manual, for those interested: https://www.manualslib.com/manual/1237352/Zilog-Z80380.html

You could run something like Inferno without an MMU: "Limbo programs run safely on a machine without memory-protection hardware". It would probably be more efficient than emulating some other architecture. Arguably, it'd be better than Unix :p

If you want to see a Unix like OS on an 8-bit CPU, get a Motorola 6809. It was designed with high level languages in mind (four 16-bit index registers, two 8-bit accumulators that can act as a single 16-bit accumulator) and can even do position independent code quite easily (PC-relative addressing modes). Quite an underrated CPU.

FUZIX is a tiny UNIX that runs on a Z80 using memory banking rather than an MMU.

https://github.com/EtchedPixels/FUZIX

I’m confused. I did a bit of Googling, and it appears that Pano Logic used Xilinx FPGAs. I’m guessing the Pano G1/G2 contains a board that the Xilinx FPGA is housed on?

At first, I was extremely impressed that a 50 employee company could design their own FPGA chip.

Right.

Here are the internals of the G2: https://tomverbeure.github.io/pano/logic/2018/12/02/Pano-Log...

So, Rev C is G2 [Edit: nope]. What's the cutoff between G1/G2? Is "Rev B" G1 or G2?

(Granted, I mostly see Rev C.)

The revs that are posted on eBay are useless, even though that’s what’s advertised. Rev C is usually G1, rev B usually G2. But not always. ;-)

The only reliable indicator to check which one to buy is looking at the pictures: VGA is G1, DVI is G2. (Some G2 are photographed with a DVI to VGA dongle plugged in, adding to the confusion.)

There are 2 G2 versions: one with an LX100 and one with LX150. You can’t know which one you’re buying...

LX100 is still a gigantic FPGA for hobby stuff.

Ah. Most of the devices on sale on ebay have VGA connectors.

Found one with DVI and just bought it, @ $22.95.

Thanks for the advice!

That’s an excellent price.

Have fun with it!

I just want to second this! I think I just ordered a LX100 for that price (plus 25US$ for shipping to ol' Europe).

//edit: Next thing tomorrow: Order the stuff necessary to program this (or check if I can use company equipment).

There are different options: my preferred one is to use something like this: https://www.aliexpress.com/item/32940620936.html

If you're willing to forgo the Xilinx special features such as ChipScope, you can also use OpenOCD and pretty much any OpenOCD compatible JTAG cable to upload a bitstream into the FPGA.

How much would it cost to buy hardware equivalent to the Pano G2 as new?

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