My next project

[Steve Cousins]

So, I'm thinking about my next project...

I want to stick with z80 at the moment and I'm thinking about trying this:

Single board standalone system

Tiny QWERTY style keyboard made with tactile switches (as often used for reset)

Graphic LCD 128x64 pixels (low cost and readily available)

- 4 pixel wide font for 8 lines of 32 characters

Z80, 128k bytes RAM, 16k or 32k bytes ROM

Serial port, probably bit-bang with option for a proper port via expansion card

A few digital I/O lines

Expansion socket(s)

It could run:

* All the usual stuff via the serial port

* A version of SCM modified for 32 character display width

I considered an alphanumeric LCD module but thought a graphic display would be more fun.

I'm guessing I could put together a kit for around 60 USD, should anyone be interested in building one.

Comments welcome.

Steve

[Richard Lewis]

Like everything except the tiny keyboard (unlike our president) I have big hands. How about an option for a PS/2 interface as well? I found an interesting discussion in stack overflow: 
How do I Interface a PS/2 Keyboard without Modern Techniques?

[Paul Williamson]

Sounds a bit like the Hackaday Superconference badge: https://hackaday.com/2018/10/17/the-supercon-badge-is-a-freakin-computer/

  -Paul

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[Greg Holdren]

My vote is for graphics display for programming fun and cool applications.

With bus?

Greg

[Steve Cousins]

Hi Greg

I'm with you on the "graphics display for programming fun and cool applications". Even a low res screen enables that.

Yes, a bus connector seems sensible. It would be a real shame not to have one.

Steve

[John Kennedy]

With a display and buttons - it’s a games console! Yes please.

[Steve Cousins]

Hi Paul, that Hackaday Superconference badge looks very impressive and is indeed a bit like the project I propose. I would, of course, want to use a more retro processor :-)

Steve

On Monday, 5 August 2019 05:05:12 UTC+1, Paul Williamson wrote:

Sounds a bit like the Hackaday Superconference badge: https://hackaday.com/2018/10/17/the-supercon-badge-is-a-freakin-computer/

  -Paul

On Aug 4, 2019, at 3:40 PM, Steve Cousins <steve...@gmail.com> wrote:

So, I'm thinking about my next project...

I want to stick with z80 at the moment and I'm thinking about trying this:

Single board standalone system

Tiny QWERTY style keyboard made with tactile switches (as often used for reset)

Graphic LCD 128x64 pixels (low cost and readily available)

- 4 pixel wide font for 8 lines of 32 characters

Z80, 128k bytes RAM, 16k or 32k bytes ROM

Serial port, probably bit-bang with option for a proper port via expansion card

A few digital I/O lines

Expansion socket(s)

It could run:

* All the usual stuff via the serial port

* A version of SCM modified for 32 character display width

I considered an alphanumeric LCD module but thought a graphic display would be more fun.

I'm guessing I could put together a kit for around 60 USD, should anyone be interested in building one.

Comments welcome.

Steve

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[Steve Cousins]

I've been thinking more about this project idea.

I think I want to make a single board standalone system, something like this.

Probable features:

Tiny QWERTY style keyboard made with tactile switches (as often used for reset)

- header for larger external matrix keyboard

Graphic LCD 128x64 pixels (low cost and readily available)

- 4 pixel wide font for 8 lines of 32 characters

Z80, 128k bytes RAM, 16k or 32k bytes ROM

Serial port, bit-bang with option for a proper port via expansion card

Expansion sockets (one horizontal, one vertical)

Still considering:

I2C (expansion module or onboard)

File storage (expansion module or onboard)

Digtial I/O (expansion module or onboard)

Possibly a simple "beep" type sounder onboard

The result might be something like this (with RC2014 module for comparison)

I am deliberately aiming for something that won't feel like a modern comfortable laptop. Back in the day many of the very early systems were very compromised and I want to capture some of the "difficult to use" look and feel. However, I don't want to just recreate one of those hex keypad and 7-seg LED display designs.

Perhaps this one is a bit of a personal journey and won't have much general appeal.

Steve

[John Kennedy]

Is there a way to add support for a rechargeable battery, and maybe some mounting holes so it can be placed in a printed case? 

I mean, you're building a pocket PC, so it should be portable :-)

I'd be in.

On Sunday, August 4, 2019 at 3:40:13 PM UTC-7, Steve Cousins wrote:

[Fredrik Axtelius]

Reminds me of the (now dead?) Pocket Chip

https://shop.pocketchip.co/collections/frontpage/products/pocket-c-h-i-p-new

--frax

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[Karl Albert Brokstad]

Yes very good idea Steve.

A step toward a portable CP/M machine.

An option could be to make 2 boards which piggy back (like a shield)

Under the screen a pcbs with cpu, memory and so on, these boards can be connected with a simpler connection

A full expansion port on the CPU board

[Karl Albert Brokstad]

Basically you have made the lower board already (SC126)

Just add a board with screen and keys on top of that board :)

Now I like my idea even more :)

Karl

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<PastedGraphic-2.pdf>

On 28 Aug 2019, at 16:32, Steve Cousins <steve...@gmail.com> wrote:

I've been thinking more about this project idea.

I think I want to make a single board standalone system, something like this.

<Z80 with LCD.jpg>

Probable features:

Tiny QWERTY style keyboard made with tactile switches (as often used for reset)

- header for larger external matrix keyboard

Graphic LCD 128x64 pixels (low cost and readily available)

- 4 pixel wide font for 8 lines of 32 characters

Z80, 128k bytes RAM, 16k or 32k bytes ROM

Serial port, bit-bang with option for a proper port via expansion card

Expansion sockets (one horizontal, one vertical)

Still considering:

I2C (expansion module or onboard)

File storage (expansion module or onboard)

Digtial I/O (expansion module or onboard)

Possibly a simple "beep" type sounder onboard

The result might be something like this (with RC2014 module for comparison)

<Z80 with LCD layout.jpg>

I am deliberately aiming for something that won't feel like a modern comfortable laptop. Back in the day many of the very early systems were very compromised and I want to capture some of the "difficult to use" look and feel. However, I don't want to just recreate one of those hex keypad and 7-seg LED display designs.

Perhaps this one is a bit of a personal journey and won't have much general appeal.

Steve

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<Z80 with LCD.jpg><Z80 with LCD layout.jpg>

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[Alan Cox]

If it takes a USB input just get one of the big chunky USB battery packs. That ought to run it for ages if halt is used properly and you are careful with the choice of panel to avoid an always on back-light. My ancient Epson px-4 can run for days on AA batteries.

On the other areas
- bit bang SD is comparable to floppy but a lot bigger
- if you space the optional keyboard pin header connectors right you can also use the replica zx80/81 keyboards for a true 1979 feel
- digital I/O, SD, bit bang serial, i2c are all basically different uses for the same I/O except for the extra glue for the i2c - and many panels BTW seem to clock stretch.
- For storage the early CP/M and related systems mostly relied upon battery backed RAM and Eprom sockets. The Epson also has optional tape and floppy but the floppy just plugged into the serial
- timer interrupts are pretty handy for games and matrix scanning/debounce

[Greg Holdren]

Something like this but Z[1]80 would be cool. :)

https://www.grappendorf.net/projects/6502-home-computer/

It would be nice if it had an optional PS/2 input for those real long intense typing sessions. :)

Maybe a horizontal add on card for the SC126. PS2 (tactile keyboard) / LCD / audio tape in-out etc.

Greg

On Sunday, August 4, 2019 at 3:40:13 PM UTC-7, Steve Cousins wrote:

[Karl Albert Brokstad]

The orange case in the 6502 project looks cool.

I am favour of using a Z180, not because it is faster, but because of the integration.

If you are to buy a Z80, a SIO/2, a CTC and a DMA, you would probably spend 3x money on those ICs alone compared to a Z180.

Additionally Z180 save space and saves glue logic for memory management etc.

Karl

[Steve Cousins]

Hi Karl,

I agree the Z180 has advantages. 

This is another example of that common question: How retro do you like your chips?

You could talk yourself up to using a modern microcontroller to emulate a complete z80 system.

I am very tempted to use a z180 but then I know what I'd end up with: An SC126 with a display and keypad (just as you suggested above). While that is not necessarily a bad thing, it doesn't feel right to me. Oh dear, the idea has just grown on me. Hm, perhaps I should do both.

Steve

[Karl Albert Brokstad]

Steve 

You have already the Z80 board --> SC114

You have the SC114 and SC126 they can operate as SBC as you have provided up until now. But maybe with some tweaking of the design, let's say V2, the users can optionally add keyboard and screen "shield", and maybe battery pack for their portable retro computer project :)

Karl

[Karl Albert Brokstad]

FYI: The Z180 was released in 1986 according to Wikipedia, it derived from Hitachis HD64180 from 1985.

[Bill Shen]

Z280 was released in 1987 (but took 3+ years to fix bugs) and significantly more sophiscated than Z180. It is also highly integrated with peripherals, but not as fast as Z180.
Bill

[Karl Albert Brokstad]

They are both fairly ancient :) 30+ years 

karl