Skip to content
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 3 additions & 1 deletion README.md
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

https://picocomputer.github.io/

Requires Sphinx:
Built with Sphinx:

https://www.sphinx-doc.org/

You can make small edits directly in the GitHub web interface.
1 change: 1 addition & 0 deletions docs/source/_static/custom.css
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
/* This file intentionally left blank. */
Binary file added docs/source/_static/ria-w-sandwich.jpg
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
461 changes: 0 additions & 461 deletions docs/source/api.rst

This file was deleted.

14 changes: 10 additions & 4 deletions docs/source/conf.py
Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,10 @@
# -- Project information -----------------------------------------------------
# https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information

project = 'RP6502'
copyright = '2023 Rumbledethumps'
project = 'Picocomputer'
copyright = '2025 Rumbledethumps'
author = 'Rumbledethumps'
release = '0.0-pre'
release = ''

# -- General configuration ---------------------------------------------------
# https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
Expand All @@ -25,5 +25,11 @@
html_theme = 'alabaster'
html_static_path = ['_static']
html_theme_options = {
'font_family': 'Arial',
'font_family': 'Arial, sans-serif',
'github_banner': True,
'github_user': 'picocomputer',
'github_repo': '',
'fixed_sidebar': True,
'show_relbars': True,
'sidebar_width': '230px', # undo alabaster's override
}
158 changes: 72 additions & 86 deletions docs/source/hardware.rst
Original file line number Diff line number Diff line change
@@ -1,93 +1,71 @@
Schematic, PCB, and Parts
#########################

Schematic
---------

`Picocomputer 6502 <_static/2023-06-07-rp6502.pdf>`_ (pdf)


Memory Map
----------
========
Hardware
========

The Picocomputer 6502 is a homebrew computer you build yourself. You don't
need to understand the electronics, you don't need to solder, but you will
need to plug the eight ICs into their sockets.

There is no ROM. Nothing in zero page is used or reserved. There isn't a
book-sized list to study. The Picocomputer design lets you start with a clean
slate for every project. VGA, USB, and WiFi are all accessed using the 32
registers of the RIA.
All parts are currently in production. The Raspberry Pi Pico 2 will
remain in production until at least `January 2040
<https://www.raspberrypi.com/products/raspberry-pi-pico-2/>`_.
The hardware design has already survived the Pico 1 to Pico 2 transition.
The manufacturing lifetime of this project is expected to extend into a time
where hobbyist ASICs are democratized.

.. list-table::
:widths: 25 75
:header-rows: 1

* - Address
- Description
* - 0000-FEFF
- RAM, 63.75K
* - FF00-FFCF
- Unassigned
* - FFD0-FFDF
- VIA, see the `WDC datasheet <https://www.westerndesigncenter.com/wdc/w65c22-chip.php>`_
* - FFE0-FFFF
- RIA, see the :doc:`RP6502 datasheet <ria>`
* - 10000-1FFFF
- RAM, 64K for :doc:`RIA <ria>` and :doc:`VGA <vga>`


The unassigned space is available for hardware experimenters. You will need to
redesign the address decoder logic hardware to use this address space. It is
recommended that additional VIAs be added "down" and other hardware added
"up". For example: VIA0 at FFD0, VIA1 at FFC0, SID0 at FF00, and SID1 at
FF20.
Schematic
=========

`Picocomputer 6502 <_static/2023-06-07-rp6502.pdf>`_ (pdf)

I use "Picocomputer 6502" to refer to the reference design with the above
memory map. Please use a differentiating name if you change the hardware. For
example, "Picocomputer VERA" or "Ulf's Dream Computer". Think about what
people asking for help should call the device and go with that.

Buying a Picocomputer
---------------------
=====================

You will need to place two orders. First, for the Printed Circuit Board.
Second, for the electronic components. Some PCB factories will do the soldering
for you, but you'll still need to order the ICs and plug them into sockets.
You will need to place two orders. First, for the Printed Circuit Board (PCB).
Second, for the electronic components. Some PCB factories will do the
soldering for you, but you'll still need to order the ICs and plug them
into sockets.

I have circuit boards in a `Tindie store
<https://www.tindie.com/stores/rumbledethumps/>`_ that ships only to the United
States. International shipping is either too slow or too expensive when
compared to getting boards made locally or in China.
<https://www.tindie.com/stores/rumbledethumps/>`_ that ships only to the
United States. International shipping is either too slow or too expensive
when compared to getting boards made locally or in China.

USA import tariffs are not an issue with this project. Only a few dollars of
resistors are made in China. Orders to my store and Mouser ship from the USA,
so you won't get a surprise bill from the courier.
USA import tariffs are not an issue with this project. Orders to my store
and Mouser ship from the USA, so you won't get a surprise bill from the
courier.

Step 0. Read This
=================

The debug header on the Pi Pico 2 W with headers doesn't fit any of the
existing cases. It's only useful for attaching a debugger to the kernel,
so just pull it off and get on with things. The Pi Picos you solder your
existing cases. It's only useful for attaching a debugger,
so just pull it off and get on with things. The Pi Picos where you solder your
own headers to do not have this clearance issue.

The boot message does not say COLOR anymore. Do not assume your device will
behave exactly the same as an old YouTube video.

The three-pin debug connections under the RIA aren't used anymore. This is an
artifact of early development.
The three-pin debug connections under the RIA aren't used anymore. This is
an artifact of early development.

Most VGA-to-HDMI cables can get power from the Picocomputer. Some will need
external power applied. All are zero lag.


Step 1. Watch the Videos
========================

To solder, or not to solder, that is the question. We're living in the future.
You can homebrew a 6502 without a soldering iron. Choose your path:
To solder, or not to solder, that is the question. We're living in the
future. You can homebrew a 6502 without a soldering iron. Choose your path:

`Here's the video where I build one without soldering.
<https://youtu.be/4CjouKoCMUw>`_

`Here's the video where I build one without soldering. <https://youtu.be/4CjouKoCMUw>`_
`Here's the video where I solder one myself.
<https://youtu.be/bwgLXEQdq20>`_

`Here's the video where I solder one myself. <https://youtu.be/bwgLXEQdq20>`_

Step 2. Order Printed Circuit Boards
====================================
Expand All @@ -109,13 +87,14 @@ you a classic green and white board with lead (Pb) HASL. Consider getting the
lead-free HASL upgrade if the other four boards will be kicking around a drawer
for the next 20 years.


Step 3. Order Assembly
======================

Skip this step if you want to solder it yourself.

PCBWay has a minimum quantity of one for assembly. They will use the boards you
ordered in step 2. What you'll have them make is a "board of sockets" - the
PCBWay has a minimum quantity of one for assembly. They will use the boards
you ordered in step 2. What you'll have them make is a "board of sockets" - the
ICs will be installed by you later. It should never be constrained on parts
availability since there are multiple vendors for every part.

Expand All @@ -126,15 +105,17 @@ Request assembly with your PCB order and send the `BOM, notes, and photos
are no surface mount parts. The default options will work. Let them source the
parts. Let them make substitutions.

There will be a short delay as they get you a price for the bill-of-materials.
Then you can pay and wait. I was estimated four weeks and got it in three.
There will be a short delay as they get you a price for the
bill-of-materials. Then you can pay and wait. I was estimated four weeks and
got it in three.

If they have a question, make sure both you and your sales rep read the notes
you sent them. If you have a question about options on their web site, ask
your sales rep before asking on the forums. They help people all day long with
you sent them. If you have a question about options on their web site, ask your
sales rep before asking on the forums. They help people all day long with
projects far more complex than this. Even if you don't understand what you are
doing, they can figure it out by looking at the zip files. Really, they do
this all day long, and will probably enjoy the easy win.
doing, they can figure it out by looking at the zip files. Really, they do this
all day long, and will probably enjoy the easy win.


Step 4. More Parts
==================
Expand All @@ -144,33 +125,38 @@ Factory assembled boards will need the eight ICs added to them. Upload the
<https://mouser.com>`_ shopping cart.

If you are soldering it yourself, upload the `full parts list
<_static/rp6502-reva-full.csv>`_ to a Mouser_ shopping
cart.
<_static/rp6502-reva-full.csv>`_ to a Mouser_ shopping cart.

Mouser will print the Customer# on each of the parts bags. Assign this
column to the CSV reference column to get your bags labelled like "C1-C9, C11"
etc. If you forget, no problem becuase the PCB silkscreen has location info.

If something is out of stock, consult the substitution notes below.

If something is out of stock, consult the substitution notes below. If it's the
Pi Pico or Pi Pico H, do a text search since marketplace vendors often have
them.

Step 5. Pi Pico Firmware
=========================

Download the `UF2 files <https://github.com/picocomputer/rp6502/releases>`_.
Download the `UF2 files
<https://github.com/picocomputer/rp6502/releases>`_.

To load firmware on a Pi Pico 2, hold its BOOTSEL button down while plugging it
into a computer. The Pi Pico 2 will appear as a storage device. Copy the RIA UF2
file to make a :doc:`ria_w` and the VGA UF2 file to make a :doc:`vga`. It should
take less than 30 seconds to copy. The LED turns on when done.

To load firmware on a Pi Pico, hold its BOOTSEL button down while plugging it
into a computer. The Pi Pico will appear as a storage device. Copy the VGA UF2
file to make a Pico VGA and the RIA UF2 file to make a Pico RIA. It should take
less than 30 seconds to copy. The LED turns on when done.

Acrylic Sandwich Case
---------------------
=====================

The circuit board is 150 x 100mm (4x6 inches). I regularly see vendors on
Amazon and eBay selling 150 x 100 x 3mm acrylic sheets. You'll need to drill
3mm holes for M3 standoffs. The recommended standoff height is >=16mm for the
top and >=3.5mm for the bottom.


Full Parts List (All Components)
--------------------------------
=================================

`All Parts CSV <_static/rp6502-reva-full.csv>`_

Expand All @@ -179,18 +165,18 @@ Full Parts List (All Components)
:header-rows: 1



Active Parts List (ICs Only)
----------------------------
=============================

`Active Parts CSV <_static/rp6502-reva-active.csv>`_

.. csv-table::
:file: _static/rp6502-reva-active.csv
:header-rows: 1


Pi Picos Parts List
-------------------
===================

Alternative part numbers for the Pi Picos.

Expand All @@ -200,7 +186,7 @@ Alternative part numbers for the Pi Picos.


Parts Substitution
------------------
===================

All resistors are <= 1% tolerance. Any power rating. Leads must fit 0.8mm
plated holes spaced 10mm apart. Recommended size is approximately 0.1" x 0.25"
Expand Down Expand Up @@ -238,7 +224,7 @@ The WDC W65C02S and W65C22S must not be substituted. Do not attempt to use
NMOS chips (without the C in the number). Some older CMOS designs may work but
there are no plans to support out-of-production ICs.

Only the Raspberry Pi design of the Pi Pico has been tested. Both original and
"H" (header) versions work great. Pin-compatible alternatives may work, check
Only the Raspberry Pi design of the Pi Pico 2 has been tested. Both original and
"H" (header) versions work great. Pin-compatible alternatives usually work, check
the forums. The 3-pin SWD connection on the Pi Pico RIA is no longer used and
may be ignored when looking for alternatives.
Loading