Re: [N8VEM-S100:7532] A new Z80 based SBC to get beginners started on the S100 bus

Hi John,

I like the idea of an S100 SBC. It would be good for beginners and could also be useful as a check-out board for reviving older systems.

Since it is aimed at beginners and you have plenty of real estate on the board, how about arranging the board into separate sections such that you have a core (required) section that contains CPU,RAM,ROM etc and various optional components, such as serial ports, Propeller VGA, parallel, Bus interface etc. The user can populate the optional parts as/when required. Fully populated it would be a proper SBC capable or running CP/M etc.

I think an SBC needs to also have some storage so maybe an optional SD card connector could be added to the top edge.

If you put a footprint for DE9 Female connectors ( with a 10 pin connector behind it) for the serial ports then the user could connect a USB-Serial adapter directly to the board without needing to make a serial cable.

I haven't seen a Z180 S100 board as yet so maybe this board would be a good candidate for this chip. The on-board peripherals would reduce the chip count and a PLCC socket is not too much of a challenge for a beginner.

So my suggested configuration would be

Required Components

Z180 CPU

512KB RAM (single chip)

512KB ROM (flash/eprom) *

*The Z180 MMU can support 1MB address space, ROM could also be ROM disk.

Optional components (requires at least one I/O device)

DE9 Female connectors for Z180 serial ports

10 pin headers for serial ports

82c55 parallel (for keypad/display)

Propeller VGA + PS/2 Keyboard

SD Card

S100 bus interface

DC Jack for 5V local power

A minimal system for example would be CPU,RAM,ROM and a serial port.If the user wants to use VGA then he adds the propeller chip and connectors. If he then wants run an operating system then add the SD card connector.

I'd suggest limiting the number of jumpers so that it is easy to build and configure.

With the local DC jack you don't initially need an S100 backplane but it could be added later to access other S100 boards.

Cheers!

Max

On Thu, Sep 10, 2015 at 5:34 AM, monahanz <mon...@vitasoft.org> wrote:

Guys, I thinking of trying to solve the chicken/egg problem by doing a single Z80 based S100 board that would contain 64K RAM, EEPROM, PS/2 keyboard input as well as a host of indicator LED's and jumpers to deactivate ROM/RAM keyboard etc. one at a time as other boards are added to get new people started on the S100 bus.

The only part I'm not sure of is what to do about console output/video. Was thinking of using the basic Propeller Console IO circuit
http://s100computers.com/My%20System%20Pages/Console%20IO%20Board/Console%20IO%20Board.htm

but this requires programming its two wire serial EEPROM with Parallaxes software and USB adaptor/software. Do you think that is outside the range capability of most
newcomers. Alternatively we could go with a straight serial output to some dumb terminal IBM PC terminal emulator. Open also to other suggestions.
John

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