That really is a whole different board but can be done for sure. Having gotten burned in the past, I hate to hard wire I/O ports. Quickly looking at the Zeta SBC board ports I see for example the FDC ports would be in conflict with the default S-100 IDE board ports (30h-33h), and the MSDOS compatible RTC (70h-71H) on the “MSDOS Support Board” seems to have the same ports but a different clock chip. The 74LS682 do most of the work for port decoding (one chip) and if we use jumpers instead of a switch real estate space in not too bad.
How do people feel about the 16550 versus the Zilog 85C30 UART. The latter is more powerful/flexible has two independent serial ports and use up only 4 IO addresses while the 16550 has only one port and uses up 8 IO addresses – something that becomes an issue in larger S-100 systems.
Can probably squeeze onboard a parallel port but probably not enough room for something fancy like an 8255.
If the idea was to make things as simple and economical to bring up an S-100 CP/M, making the support card provide memory and console is cool, but you would want to clump all the I/O spaces together and place them at zero so you don't need switches and decoders. You would only need to decode as many bits as are require to hit all the actual concatenated I/O spaces. If the memory mapping was the same as SBCV2, that would make things easier also. If you used 16550, that makes things easier also. If you can squeak in a parallel port, that opens it up to PPISD/PPIDEd usage. If you did that, you would have memory, console, and persistent storage. That is the whole ballgame for a minimum system.
On Dec 6, 2012, at 12:16 PM, John Monahan <mon...@vitasoft.org> wrote:
Yes. It might make sense to actually try and combine the RAM+ROM and a serial port on one board. The thing that is using up real estate on the REPROM board is trying to have a lot of flexibility on the one board with addressing over the 16MG range 8 bit ROM’s as well as FLASH etc. If we could agree on a priority list working down the list I can squeeze more on, I think. Andrew has worked wonders these days getting stuff on S-100 boards (e.g. 80386!). BTW an “IOBYTE” port is very useful when doing configuration options, may want to consider that as well. We have it on the SMB but not here.
From where I stand, a Zeta type system is the closest we can come with several
of the S100COMPUTERS boards to a configuration similar to the Zeta.
512Kram 512Krom, serial port for Console, and CF for persistent storage.
I am seeking a baseline version, generated from a fork of the RomWBW BIOS
and applications. With storage media transportability to SBC V2, Zeta, and N8.
Once we have that baseline, we can evaluate and prioritize supporting other
Does that answer the question John?
On Dec 6, 2012, at 10:34 AM, John Monahan <mon...@vitasoft.org> wrote:
Tom what is a “Zeta type system”?
Doug and I are working on a version of the ROMwbw CPM that will require an updated rom-ram board. This will be a Zeta type system. So I hope we can get a new one in the que.
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