Hi all,

8bitforce.com created some PCB designs for several variations of their RetroShield, which is a shield for the Arduino Mega (or pin-wise equivalent) allowing it to interface with various 8-bit microprocessors. The Arduino is then responsible for driving the microprocessor's clock, servicing memory requests, etc., providing a cheap, easy way to explore the workings of these processors.

I received the 6502 and Z80 variations in a subscription box (no longer available) and decided to order more*, plus a variation for the RCA 1802 microprocessor. I had to buy in multiples of 5, and 10 costs the same as 5,
so I ordered 10 of each: 6502, Z80, and 1802. The total cost was $35.99, $24
of which was shipping.

I ordered from NextPCB.com and submitted the gerber files located here: https://gitlab.com/8bitforce/retroshield-hw/-/tree/master/manufacturing (the gerber files are in a zip file within each processor-specific directory).

I'll let you know how the final boards turn out, if anyone is interested in doing the same. Assembly of the boards does require acquiring and soldering a few smd components (resistors and capacitors), as well as a processor-appropriate socket (if desired), an LED, an 18x2 male header, and
of course a processor chip.

More info on the boards can be found here: http://www.8bitforce.com/projects/retroshield/

Jeff.

* The 6502 and Z80 chips that came with the kit were vintage chips pulled
from who-knows-where. The 6502 board has a pair of solder pads that need to
be bridged for older chips, but left unbridged for modern 6502s. Since the
chip I had was an older one, I bridged them. However, the modern chips are better in a number of respects (including being more tolerant of Silly User Mistakes) so I'd like to use that. I also have a few spare 1802s since I had
to buy 5 to get the 1 I needed for another project. So that's how I came to order 30 PCBs.

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On 10 Jan 2022, Jeff said the following...

I ordered from NextPCB.com and submitted the gerber files located here: https://gitlab.com/8bitforce/retroshield-hw/-/tree/master/manufacturing (the gerber files are in a zip file within each processor-specific directory).

I'll let you know how the final boards turn out, if anyone is interested in doing the same. Assembly of the boards does require acquiring and soldering a few smd components (resistors and capacitors), as well as a processor-appropriate socket (if desired), an LED, an 18x2 male header, and of course a processor chip.

The PCBs arrived and I assembled one of the 1802 (COSMAC) boards. It successfully runs at about 100kHz driven by an Arduino Mega. Since the 1802 requires 8 clock cycles for each machine cycle, and most instructions take
1-2 machine cycles, this works out to about 8000 instructions per second.

The 1802 is a very unique chip, a significantly different approach to an
8-bit microprocessor than the 6502, Z80, etc.

Jeff.

--- Mystic BBS v1.12 A46 2020/08/26 (Raspberry Pi/32)
* Origin: Cold War Computing BBS (21:1/180)

Re: RetroShield for Arduino
By: Jeff to All on Mon Jan 10 2022 09:48 am

so I ordered 10 of each: 6502, Z80, and 1802. The total cost was $35.99, $24

Hey Jeff, where did you order the Z80s from? I was looking for a reliable source for a single-board computere project I was going to do for my kid to teach him what goes in inside a computer (kind of) ...
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On 23 Jan 2022, Fr333n3rgy said the following...

so I ordered 10 of each: 6502, Z80, and 1802. The total cost was $35.99

Hey Jeff, where did you order the Z80s from? I was looking for a reliable source for a single-board computere project I was going to do for my kid to teach him what goes in inside a computer (kind of) ...

In that particular instance, I was referring to PCBs for use with Z80s, but
as far as the Z80s themselves... Digikey has several different varieties (https://www.digikey.com/en/products/detail/zilog/Z84C0010PEG/929206 for example) as does Jameco (https://www.jameco.com/z/Z80-CPU-Major-Brands-IC-Z80-CMOS-CPU-2-5MHz-DIP-40-pi n_35561.html for example).

Jeff.

--- Mystic BBS v1.12 A46 2020/08/26 (Raspberry Pi/32)
* Origin: Cold War Computing BBS (21:1/180)