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I've been reading the FAQ section of the Raspberry Pi official site and I've noticed there was a list of all the devices ever made, which are (as of June 2016):

  • Raspberry Pi Model A
  • Raspberry Pi Model B
  • Raspberry Pi Model A+
  • Raspberry Pi Model B+
  • Raspberry Pi Zero
  • Raspberry Pi 2 Model B
  • Raspberry Pi 3 Model B

My questions are:

  1. Aren't there a Raspberry Pi 2 Model A and Raspberry Pi 3 Model A ?
  2. If there aren't. Why was A skipped?
  3. Is there a major distinguishable difference between A and B models independent of the generation?
YetAnotherRandomUser
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VMMF
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  • The original A and B are as distinct as the A+ and B+. You can find stats and pictures for all of them online to find the differences. As to why there's no 2/3 A, maybe it's like the [coupe utility](https://en.wikipedia.org/wiki/Coup%C3%A9_utility) -- a cool idea that's overlapped and overshadowed in practice. – goldilocks Jun 23 '16 at 04:07

4 Answers4

8

There is currently (23rd June 2016) no 2A or 3A.

The Raspberry Pi 2A was skipped because development and production of the Pi 3 was already underway and the A+ was still felt to be 'fit for purpose'. The Raspberry Pi 3A is expected sometime this year, according to Eben Upton.

The A differs from the B by: a) number of USB ports (1 for the A/A+, 2 or 4 for the B/B+/2/3) b) ethernet port (A/A+ has no port, B/B+/2/3 does) c) memory differences (A generally has less memory than the corresponding B etc)

recantha
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5

The naming scheme for Raspberry Pi's is as follows:

  • "A" models have no on-board Ethernet and only 1 USB header
  • "B" models have on-board Ethernet and 1 or 2 USB headers (2 and 4 ports, respectively)
  • "B+" models have an additional onboard USB header (max 2 headers, for 4 ports)

This naming scheme was developped for the original Raspberry Pi which went through incremental changes in said order. The major revisions (RPi2 and RPi3) only added more processing power, more RAM and onboard WiFi and Bluetooth, and kept the most common configuration of Ethernet + 4 USB ports, since that's what most users were wanting, which corresponds to the "B" or "B+" versions of the original RPi.

tlhIngan
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    There's an A+ as well. The B+, 2, and 3 have identical form factors but different processors. Another major difference between the +/2/3/0 and the A/B is the former use micro SD cards. I may be wrong, but as I remember it, when the 2 was first released, it was just the "Pi 2" -- they suddenly started calling it the "2 B" within a few months, I guess to include it in the line that has ethernet and multiple USB ports, although "2 B+" would be more accurate since it's just a quad core B+. Perhaps because there is no quad core version of the original form factor, the + isn't necessary. – goldilocks Jun 23 '16 at 03:46
  • They shoulda called it a B+, I agree. – tlhIngan Jun 23 '16 at 03:48
  • Well -- put another way, I think the 2 and 3 got called "B"s because of a community colloquialism. As to why they don't have a quad core A+, I would guess sales numbers, niches, and production line limitations. They shoulda given them all more distinct names IMO. OTOH, it might just lead to people thinking they are more different than they actually are. – goldilocks Jun 23 '16 at 03:52
5

What happened to Raspberry Pi 2- and 3- Model A?

Basically they never got arround to making them.

Is there a major distinguishable difference between A and B models independent of the generation?

The "B" models have the USB hub with Ethernet chip while the "A" models do not. Therefore A models only have a single USB port and no Ethernet port. A models also have less ram than contemporary non-legacy B models.

A quick history of regular A/B Pi models (not zero or compute module).

Raspberry pi borrowed the terms "model A" and "model B" from the BBC Micro. The BBC model B was the "full-spec" version while the BBC model A" was a cut-down model with half the ram and many of the interfaces missing, but still built on the same PCB.

So it was with the originally announced raspberry pi models. The model B as originally announced and released had 256MB of ram. It also had two USB ports and an Ethernet port provided by a LAN9512 USB hub with Ethernet chip. The model A was announced as a cheaper model with only 128MB of ram, a single USB port and no Ethernet, so it could skip the relatively expensive LAN9512.

The Raspberry pi B was released first as that was deemed to be the more useful model for early adopters and developers. This was followed by the "catestrophic unplanned success" which tied up most of the Raspberry pi teams efforts for a while.

So the model A ended up being released over a year after the model B. By that time the ram had been increased to 256MB for the model A and 512MB for the model B. They had also added two holes to the PCB that were officially not mounting holes but everyone used them as such anyway.

Then came the B+, with it's extended GPIO header, two extra USB ports (enabled by replacing the LAN9512 with a LAN9514) and four proper mounting holes in sensible positions. The A+ followed bringing the GPIO and mounting improvements to an A model Pi. Unlike the original model A which shared the same PCB as the model B the A+ had a dedicated smaller PCB.

Then came the 2B with a doubling of ram and a quad-core A7. A 2A was mooted, but they never got around to making it. I understand that this is because by the time they had got over the problem of dealing with 2B demand the raspberry pi 3 was well on it's way. They did however quietly increase the ram on the A+ to 512MB.

And then came the 3B with it's cortex A53 and 2.4GHz wifi, again a 3A was mooted but never actually came out. Again I understand this was a case of by the time they had dealt with demand the 3B+ was already well on it's way.

Then came the 3B+ with it's improved power and thermal management, faster Ethernet and dual-band wifi and then finally they got around to producing the 3A+.

Peter Green
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2

Finally - as of November 2018 - there is a Raspberry Pi 3 Model A+; which the Foundation states is

[...] one of our most frequently requested “missing” products.

By the way, the Foundation also points out

[...] that the 3+ platform is the final iteration of the “classic” Raspberry Pi: whatever we do next will of necessity be less of an evolution, because it will need new core silicon, on a new process node, with new memory technology. So 3A+ is about closing things out in style, answering one of our most frequent customer requests, and clearing the decks so we can start to think seriously about what comes next.

  1. Is there a major distinguishable difference between A and B models independent of the generation?
  • Smaller form-factor (except for the first generation of the Pi 1, which has the same form-factor for models A and B)
  • less RAM (except for the 1A+ and 1B+, both have 512 MB)
  • just one USB port
  • no wired LAN / ethernet port
  • typically a lower power consumption due to the lack of the missing USB-hub / LAN controller
Ghanima
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