In the world of retrocomputing it’s the earliest models that garner the most interest, usually either due to their rarity, or sometimes just because of their flaws. The Commodore Amiga 1000 is a case in point, it was the machine everybody wanted but its A500 home computer sibling made the Amiga a success story. Peripherals for the 500 are plentiful then, while those for the 1000 remain a rarity. Thus it’s a treat to see an A1000 peripheral appear in the present day, in the form of a memory, clock, and SD card expansion called the Parciero. It packs 8Mb of SRAM to give the Amiga some truly quick fast memory, something that would have used an eye-wateringly expensive brace of chips back in the day but now has just a single package.
We like the description of the Parciero’s case as “about the size of a harmonica that’s been run over by a steam roller“, but it conceals the effect of the march of technology. Amiga enthusiasts are used to their peripherals being chunky affairs full of through-hole chips. Its creator [David Dunklee] is a retired senior US Space Force officer, and we appreciate his humour in the silkscreen layer. It’s a small-scale commercial product, but in a field so select as Amiga 1000 owners it’s unusual enough to make it noteworthy to all retrocomputer enthusiasts by virtue of its mere existence. We congratulate him for helping keep that little corner of vintage technology alive.
The Amiga 1000 may be the original, but it’s possible that it may not be the rarest Amiga.
Found one type: 8Mb stands for 8 Mbit which is 1Mbyte, but I guess the expansion is 8MB, so 8 Mbytes
Convention is that MBytes are used to describe size of storage
Mbits are used for data transfer.
But not everyone uses that convention and some companies are actively misusing it for marketing purposes. So at this stage I wish we would stick to MB for everything.
I’m regretting giving mine 1000 away about 10 years ago.. Just had too much old computer stuff for a location shift..
I was force to see a bunch of stuff on eBay before my move. I had on original PC motherboard, a Kypro II and several PS 2’s. Plus numerous Commodore stuff including a Plus 4 (I used to set it up so my youngest daughter could bang away on the key and not both my keyboard when was working)
Yeah, that wasn’t the best decision really, given the prices today for A1000 stuff. I mean, it’s not Tesla/Apple/Bitcoin level gains, but …
Same here. I had to downsize and it went to a good home, but I miss the old girl.
I miss the non PC/Apple computers of the era. People were running with so many good ideas. It was a special time.
Me too. Donated my equipment to the Palo Alto Amiga Users Group
Looks like a 3V ram connected directly to the bus, maybe in a system like this with a bunch of 5V TTL it doesn’t matter too much but if there are pull-ups on the bus like there are in an A500 how long will that ram last?
3.3V CMOS devices can sometimes connect directly to a 5V TTL/NMOS bus. For inputs, you should have 5V tolerance and a 2V VIH,min threshold. So a straight-up CMOS chip is a no-go, but some are designed for compatibility. On the output side, you’re generally good, depending on the load present. Though it’s easy enough to use level-shifters.
TIL: Alliance makes a $25 8MB (4MB x 16) SRAM chips now :o AS6C6416
Together with Lattice MACH 4000V 5V tolerant I/O this enabled super simple design of Parciero extension, there is barely anything on the pcb, very clean.
Wait a minute, https://www.alliancememory.com/wp-content/uploads/pdf/Alliance%20Memory_64M_AS6C6416-55TIN%20v1.0%20July%202017.pdf says AS6C6416 is not 5V tolerant. Absolute max is VCC+0.5V with VCC at 4.6V. I see a 3.3V regulator, but no other supply sources. What is going on?
You can run different IO banks on the FPGA at different voltages.
So the IO bank interfacing with the AMIGA can run at 5V levels and the one talking to the RAM at 3V3 or less.
But in this case it seems like the chip’s IO is run at 5V levels from the bus, but some of the pins are connected to the Lattice FPGA. So who knows.
Have seen this a few times in other Amiga projects where 3v ram is used and seems to work maybe because the average voltage is lower (since data and address are always changing) or because the Amiga drives mostly TTL levels.
Idk if I’d gamble on that for a product I was selling
The CPLD/FPGA sits between the 3V3 SRAM and the 5V bus, and thus ‘protects’ the SRAM.
The CPLD/FPGA is a 3V3 part with 5V tolerant pins.
The RAM is obviously connected to the bus directly too as evidenced by the traces visible clear as day
I saw the pcb after posting this. Probably it works the way you describe in the other answer.
Prone to failure in the future. Although I ‘ve SNES carts from china doing the same and still working…
SNES/NeoGeo etc cartridges have it easier because they are read only, and they can get away with simple hacks like resistors/diodes on address bus. Here 3.3V SRAM $25 part is just plonked onto 5V bus like its no problem.
They do it without any resistors. Same config as here.
It probably works for a while if only because the average voltage will be below the absolute max of 4.6V but it seems risky selling a commercial product like this as it will probably die at some point. A couple of TSSOP buffers would solve that easily without taking up a lot of space
5V power rail =/= 0-5V signal swing for non-CMOS parts. Stock Amiga 1000 has unbuffered address/data bus on the expansion bus driven from NMOS 68000. NMOS and old TTL parts have a hard time driving signals close to the +ve supply.
The address lines are unlikely to reach 5V level. The keword is stock. The assumption is that there are no other *bus masters* with CMOS parts driving it. You have used up 8M address space and no provode a daisy chain on the expansion port, so that’s probably okay. Could run into problems with accelerators e.g. 16MHz 68HC000 board hacked into the CPU socket.
The data bus side is a bit more complicated. It is shared by the ROM/kickstart board, 74LS buffers, NMOS CIA, NMOS(?) custom chipset and god knows what expansion boards the user installed. The latter is where you can run into issues with CMOS parts that can drive rail to rail violating the absolute maximum specs of the SRAM chip. That and noisy bus overshoots.
Personally I would not take short cuts like this. Buffers can be used and the SRAM is pretty darn fast so there are no speed penalities.
A stock A1000 has an NMOS 68000… we didn’t switch to the CMOS 68000s until mid-way through the A2000/A500 run … you needed a Rev 6 A2000 for full CMOS compatibility. NMOS and TTL outputs on a 5V bus don’t get all that close to the rail, but there’s no guarantee they’re below 3.3V either.
I would not use the experience of cheap Chinese knock-off products as a basis for proper product engineering.
The real Dave Haynie shows up and no one comments? :-)
Is this comp.sys.amiga.advocacy?
This is why I come to HaD. Thanks for sharing, Dave! (Are you really the real Dave Haynie? If you are, thanks again for the great computers back in the day.)
“Its creator [David Dunklee] is a retired senior US Space Force officer”
Wait, what?
Retired Space Force Officer is a thing already? Must have transfered at the very end of his career, gutsy move! I bet this peripheral is far from being the most interesting story he has to tell if he is allowed to talk about any of them.
Why?
2021 – 1970 = 50 years.
“Its creator [David Dunklee] is a retired senior US Space Force officer…”
Is the service old enough to have retired people already?
If you retire the service, does everyone retire by default?
I mean, he probably started his career in Air Force or something, obviously
Well you could have for instance, joined the US Army Airforce in 1938 and retired a Captain of the USAF in 1948.
It’s most likely in this instance he was USAF before that, but personnel could have transferred in from the Strategic Command elements that performed the mission since the abolition of Space Command, which was a joint service org. They got an Army guy heading it up at the moment? I don’t keep up.
Love the PCB shots on the linked page, very cool seeing a Last Starfighter reference in the wild.
oh, yes, the ko-dan armada
Click the link, then move your mouse pointer around the screen. :D
Sabrina would be pleased!
Most will not get the reference.
This is an amazing device that caught my attention fully when I first read of it the other day. I ordered immediately and have (apparently) the fourth unit made on the way to me in the mail right now. I will be using it on my Amiga 1000 system to replace the Microbotics StarBoard II interface (2MB RAM, SCSI, RTC) and its two spinning hard drives. (The system is pictured in my recent blog post about 35 years Amiga: https://bytecellar.com/2020/10/27/looking-back-on-35-years-as-an-amiga-user/ ) The ability to mount the SD in a modern Mac/PC and load apps to the Amiga’s “disk” so easily in that fashion is going to me amazing!
The SD card is so useful. Dump the spinning rust.
On a mostly nude A1000 this looks good – others above mention adding buffers in case of adding a faster CPU or similar, but if you want a raw A1000 + RAM + Storage solution, this is nice.
Me watching the PCB
Warp Core, Arrakis, Ko-Dan Armada (The Last Star Fighter), Flux Capacitor..
Truly somebody put a lot of heart ♥ on this hardeare.
yeah. that’s some condensed 80’s stuff in one place. love it.
This is around the time tbat stereo receivers went to transistors, but the cases remained huge as “noone will pay 600$ for one if it’s so tiny.” So to make his device period correct it ought to be this tiny thing that it is, residing inside of something the size of a cigar box, give or take.
Not just size, but WEIGHT! That heft implied value, as well as durability. The knobs felt sturdy; the switches had a solid click to them.
Yeah, the side expansion bus RAM expansion I’ve got somewhere for an A500 kinda fits the description. It’s a couple inches wide and made from 1/16th steel, could use it as a blunt force instrument. Only 512K too. Made by a German company I can’t recall name of right now, and it’s packed somewhere. It’s similar to the Kupke Golem ones. Just has a little board in, that’s mostly expansion bus and passthrough connectors, and the RAM, 90% of the volume wasted. I was kind of excited when I bought the thing, in a box of random Amiga bits, thinking it was AT LEAST an 020 accelerator (Looks big enough) but bummed out when I got it home and looked up the model number. Didn’t pay much, so not cheated per se, just didn’t make out as good as I thought I was.
About to make the upgrade!
Pic:
https://www.flickr.com/photos/blakespot/50833695956/in/album-72157621596272210/