Pocket sized RomWBW system

[Steve Cousins]

Hi All,

I've finally received the batch of PCBs I've been waiting for from China since January 14.

These boards are for my prototype pocket RomWBW system.

I've got a few tweaks and some testing to do and then I intend to offer it as a kit. I plan to offer a choice of case colours and a choice of front and back panel colours.

Specs are:

Z180 CPU, 18.432MHz, 512k Flash, 512k RAM, 2 serial ports, MicroSD card slot. No further expansion if possible.

Steve

[Bill Shen]

Very cool and very impressive.  I like the idea of designing specifically for an enclosure.  Great work!
  Bill

[Bill Shen]

Another comment:  Black face plate would goes very well with the enclosure as well, especially if you have nice lights.  The clamshell enclosure I used years ago was Pactec CM5-225 which has inside pc board dimension of 4"x4" and faceplate slots specifically for standard 1.6mm pc board.  It is perfectly sized for boards from JLCPCB.

  Bill


On Wednesday, February 26, 2020 at 8:45:15 AM UTC-7, Steve Cousins wrote:

[Steve Cousins]

Thanks Bill,

That case is a standard Hammond 1593. It is readily available in black, grey, and translucent blue. I plan to offer all three case colours as options in the kit. I think any of the PCB colours available from fabricators could be used depending on the taste of the individual, but I think I will try black, blue, green, and white initially.

Steve

[Tom Szolyga]

Great looking enclosure and excellent board design!  Outstanding work!

Tom

[Wayne Warthen]

Just awesome!  I definitely need one of these!

-Wayne

[Richard Deane]

Yes indeed, perhaps an early birthday present to myself.

Definitely a smart looking box.

Richard

[Sergey Kiselev]

That looks great!

My only comment would be about the serial port connectors. Pin headers are a bit flimsy (especially right angle ones) and they are normally not designed for multiple mating cycles.

Perhaps something like this https://www.mouser.com/ProductDetail/538-70551-0074 would work better?

On Wednesday, February 26, 2020 at 7:45:15 AM UTC-8, Steve Cousins wrote:

[Karl Albert Brokstad]

Hi Steve

Would it be possible to fit a raspberry pi micro in the case giving keyboard and screen connection? I know there is not much space .

Karl

[Richard Deane]

A Pi Zero would probably fit next to the sd card, the pi zero with no headers is very slim. Perhaps 4 mounting holes in the sc131 pcb, and some shallow standoffs.

Richard

[Steve Cousins]

Thanks for the feedback guys. I'll give it some more thought.

Sergey: I've found the angled header pins to be reliable connectors but I take your point. With the current layout, the serial port under the SD card has space restricted by the stand-offs supporting the SD card. A shrouded connector would not fit there. It may be possible to move things around to fit such a connector. More thought required.

Karl/Richard: I doubt the Pi would fit with all the obstructions already there but even if it did I don't think the connectors can be facing the back panel. The Pi is too wide to fit that way around. Not sure I want a powerful modern processor in my retro box!

When I purchased these cases I also got the next size up, which is much bigger. This case would be better suited to a more highly featured system. Perhaps the next design could use this case.

One observation after having a cased unit on my desk for a few days: Having the unit cased gives it a completely different feel to the usual open PCBs.

Steve

[Karl Albert Brokstad]

I agree there is no place for a raspberri pi zero in a low cost and bare bone system. 

As the front and back plates are PCBs, maybe som of the electronic could be migrated here.

Karl

[Rob Gray]

It's refreshing to see a design that actually considers an enclosure, very few do, if thought of at all it's an add on that has to work around various limitations because it wasn't built in to the design.

Actually I have always found the selection of an enclosure to be the hardest part of a project :)

Rob

[Mark T]

Design to suit a case is a great Idea. The SC-126 and SC-130 looked difficult to build a case around with so many side connections and switches.

Mark

[Brian Welland]

Steve,

Following from Karl's suggestion regarding the possible use of a Raspberry Pi have you considered using a stripped down version of Geoff's ASCII terminal by use of either a small daughter board or making use of the rear case end plate using SMD style parts . By using a micro USB connector for the keyboard and a VGA monitor for the video (almost all small LCD screens still have this mode available) you will have a compact system available which doesn't need the use of a PC based terminal etc.

Brian 

On Sat, Feb 29, 2020 at 2:52 AM Mark T <mark...@gmail.com> wrote:

Design to suit a case is a great Idea. The SC-126 and SC-130 looked difficult to build a case around with so many side connections and switches.

Mark

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[Brian Welland]

Giving this a little more thought mount both the USB and VGA connectors on the front plate and leave the electronics (PIC etc) where it fits inside on suitable spacers ie above the ROM/RAM chips.

Brian

[Richard Deane]

That could be a project add-on, not necessarily from SC, just slip in a suitable enhancement end board. Could also do a design for one to mount a led with bluetooth or wifi serial.

I personally prefer direct serial as in current SC131 design to get high baud rates and crisp font on high res screen - VGA and HDMI don't look as crisp and are more limited in screen size when editing text or looking at program listings. 

Richard

On Saturday, 29 February 2020 07:57:38 UTC, Brian Welland wrote:

Giving this a little more thought mount both the USB and VGA connectors on the front plate and leave the electronics (PIC etc) where it fits inside on suitable spacers ie above the ROM/RAM chips.

Brian

On Sat, Feb 29, 2020 at 8:38 AM Brian Welland <brwella...@gmail.com> wrote:

Steve,

Following from Karl's suggestion regarding the possible use of a Raspberry Pi have you considered using a stripped down version of Geoff's ASCII terminal by use of either a small daughter board or making use of the rear case end plate using SMD style parts . By using a micro USB connector for the keyboard and a VGA monitor for the video (almost all small LCD screens still have this mode available) you will have a compact system available which doesn't need the use of a PC based terminal etc.

Brian 

On Sat, Feb 29, 2020 at 2:52 AM Mark T <mark...@gmail.com> wrote:

Design to suit a case is a great Idea. The SC-126 and SC-130 looked difficult to build a case around with so many side connections and switches.

Mark

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[Steve Cousins]

Thanks for the feedback.

I can see there is interest in a standalone cased retro computer (with ports for monitor and keyboard).

While it is not impossible to add that functionality into the existing case, it is problematic as there really is very little unrestricted space. I want to design things that can be made reliably by hobbyists. I, therefore, want to avoid surface mount components that need soldering. The microSD adapter is okay as it is an off the shelf module, although it grates a bit using it in a retro computer kit. I don't think there is an equivalent video and keyboard module with connectors in the right place and small enough to fit in this case.

I see a few possible ways forward.

Build a general-purpose serial to video/keyboard interface in a matching case. These could be stacked with a short serial cable linking them. Not elegant but practical. One advantage of this is the video/keyboard interface would be a nice neat device that could be used with almost any retro hardware. Marco has some designs which I think would require very little modification to build into this case:

https://www.maccasoft.com/en/electronics/vga-serial-terminal/

Build a similar SCZ180 device in a larger case. I purchased a suitable larger case at the same time I got the small one.

I think this would have room for a motherboard with additional features, plus connector(s) for a daughterboard or two. Front and back panels could easily be produced to match the needs of the daughter boards. I think this is the way to go for the next design.

Steve

 

[Bill Shen]

This is an interesting discussion for me.  I've done several designs targeting a specific case, acrylic Arduino Mega case.  I haven't sold many of them so I don't have user feedback, so I'm very interested in these comments.

This is my thought process: the design-for-case is one of the end product of a product line.  This end product is narrowly tailored for a case so flexibility and options are limited.  Leading to this end product is a general purpose platform (motherboard with expansion slots & many connectors) for experimentation.  What I've heard is the users may want to convert the end product back to the general purpose platform.  To that end, a "bridge board" to backplane may give the end product greater flexibility.

In my case, the general-purpose platform for developing Zuno (Z80 for Arduino Mega case) is Z80MB64; the general-purpose platform for developing MicroZ is Micro80; the general-purpose platform for developing Kuno is P90MB.  I'm currently working on ZZ80MB (Z280 motherboard) with ZZuno (Z280 for Arduino) in mind.  All the end products have a vestigial RC2014 connector (26-pin I/O only connector) and an optional bridge board to return them to general purpose usage.

  Bill

[Bill Shen]

I took a picture of Z80MB64, bridge board, and Zuno.  The other platform/cased pairs look pretty much the same, i.e. a 4"x4" mother board with several expansion slots leading to an Arduino cased product with a truncated expansion bus.
  Bill

[Steve Cousins]

Hi Bill,

Interesting analysis.

I agree with your thinking about a modular system being the development platform and the end product being tailored to a specific specification. I differ, however, with the idea of making THIS specific optimal end product expandable. I feel for a small cased unit this is too much of a compromise. Perhaps the larger case version could offer this feature, but I'm currently trying to design a pocket-sized system.

One thing is for sure and that is there is plenty of room in this field for different solutions :)

Steve

[Bill Shen]

Hmm, design for a case but with some expansion capability may be a more general solution.  In my approach, the clear acrylic case showing off the components of retro technology also expose the interior of the design so it needs to look orderly inside the case.  That's the unintended consequence of acrylic case.

I just received a cased CP/M-ready Z180 from wsm of retrobrewcomputers.org.  I thought it is quite impressive!  But (if I'm so bold to criticize wsm's fine work) I thought the "retro-ness" is lost with this level of miniaturization.
  Bill

[Steve Cousins]

Bill. 

Perhaps this is not about the size of the design but the style. You have clearly shown that a small form factor can have an expansion socket.

On reflection, therefore, it isn't the pocket size that makes me think an expansion socket is too much of a compromise, but the style of the case. A sort of Steve Jobs thing, where functionality is sacrificed for style. You know: we don't want screws showing... and we definitely don't want an ugly row of holes for some expansion system!

I agree that there is a limit to miniaturisation before a design no longer looks retro. Having real through-hole resistors with nice colour bands is a must for me.

Steve

[Tadeusz Pycio]

 "retro-ness" is lost with this level of miniaturization.

  Bill

Hi,

Sometimes it is worth having something in your pocket that extends access to retro equipment outside your own workshop. If this is not the main direction of development, why not? It's a better solution than a computer emulator.

 

[Myklhn]

Bill,

I, for one, would be interested in the design that started this discussion. Put me down for one when you’re ready to start selling the kit, please.

Michael

[Alan Cox]

Build a similar SCZ180 device in a larger case. I purchased a suitable larger case at the same time I got the small one.

I recognize that case. I have one with an SC126 in (a shade smaller than that I think), one with the Tiny68K 8) and a tall one with the SC114 and backplane. The SC126 is set up so that the sticking out edge connector is exposed at the back like the old 8bit home computers. The serial goes to USB adapters mounted internally with the USB connector on the case and the SD card likewise is accessible on the rear.

Old index card drawers (bigger sizes) fit the backplane based machines.

I do wonder if perhaps all it needs is the SC126 with the mounting holes juggled a bit to match the case and the reset and switches replaced with jumpers so you can fit them to the case and connect them to the board (which is far easier IMHO than lining stuff up).

Now how about a long flat backplane with cards coming off each side for the 1U rack mount ;-)

Alan

[Rizal Acob]

Hopefully Steve will offer an option for the system as a kit only minus the case. I like building my own cases.

[Eric Matecki]

Now how about a long flat backplane with cards coming off each side for the 1U rack mount ;-)

That's a nice idea.

With one of the ethernet cards in development, it would make a nice small server for a low bandwidth service like DNS on any home network :)

[Greg Holdren]

Eric,

Which of the Ethernet controllers are you using?

I have some Lantronix XPort jack modules I'd like to hook up to a spare serial port. On the project list.

Greg

[Eric Matecki]

Hi Greg,

 

Which of the Ethernet controllers are you using?

*I* don't use any...

I was talking about what other's are building :)

Right now I have so little time all my RC2014 projects (not many) are on hold.

I fire my '14 up maybe once a month for a two hour CP/M nostalgia session, that's all I can do for now :(

[Interocitor Steve]

Sign me up.  Will it be posted on Tindie?  =Steve.