Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 8:41 AM, Tapley, Mark via cctalk wrote: On Nov 19, 2017, at 11:54 PM, Chuck Guzis via cctalk wrote: So we agree on parallel standard buses, that STD bus is a strong contender with varied processor base. Catching up late, sorry if this is an old

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 6:50 PM, Noel Chiappa via cctalk wrote: > From: Charles Anthony > a hybrid PDP-11 (16 bits) / PDP-15 (18 bits) on a shared bus (UNIBUS?) That's a UNICHANNEL-15: it allowed devices on the -11 to do DMA directly into the PDP-15's memory through the MX15-B Memory

Re: Ideas for a simple, but somewhat extendable computer bus

> From: Charles Anthony > a hybrid PDP-11 (16 bits) / PDP-15 (18 bits) on a shared bus (UNIBUS?) That's a UNICHANNEL-15: it allowed devices on the -11 to do DMA directly into the PDP-15's memory through the MX15-B Memory Multiplexer. Odd factoid: this UNIBUS could run in 18-bit mode

Re: Ideas for a simple, but somewhat extendable computer bus

On Nov 20, 2017 7:41 AM, "Tapley, Mark via cctalk" wrote: Catching up late, sorry if this is an old question, but what did the Digital Group computers use? My recollection is that they offered cards with 6800, 6502, 8080, and Z-80 CPUs on the same bus, and that

Re: Ideas for a simple, but somewhat extendable computer bus

Am 19.11.2017 um 16:08 schrieb emanuel stiebler via cctalk: On 2017-11-18 23:48, Jim Brain wrote: > Looking at the schematic for the ECB, I cannot find any description of > the signals BAI, BAO, IEI, and IEO.  Can anyone shed some light on the > function of these signals? Here again:

Re: Ideas for a simple, but somewhat extendable computer bus

On Mon, Nov 20, 2017 at 5:40 AM, allison via cctalk wrote: > Creating a bus to accommodate any one cpu at a time is far more > straightforward and there are plenty of > examples than one that is running a mix of many cpus. > > Dim memory of U. of. WA School of Dentistry

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 11:37 AM, allison via cctalk wrote: > I did that back when with a S100 machine expanded with multiple > Z80s(local ram and MMU), global mmemory and 8085s and 8749s to have > intelligent peripherals and shared loading and tasks. An interesting > experiment and some elements still

Re: Ideas for a simple, but somewhat extendable computer bus

> From: Allison >> I would seriously consider shared data/address lines, like on the QBUS. > QBUS is wrapped around a subset of PDP11 and the unique processors made > to fit it. I did say "like ... the QBUS", not "the QBUS"! I was just trying to make the point that the original

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 01:18 PM, Chuck Guzis via cctalk wrote: > On 11/20/2017 05:40 AM, allison via cctalk wrote: > >> Creating a bus to accommodate any one cpu at a time is far more >> straightforward and there are plenty of >> examples than one that is running a mix of many cpus. > Oddly enough, I'm in

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 05:40 AM, allison via cctalk wrote: > Creating a bus to accommodate any one cpu at a time is far more > straightforward and there are plenty of > examples than one that is running a mix of many cpus. Oddly enough, I'm in agreement. :) Today, it really makes little sense to have

Re: Ideas for a simple, but somewhat extendable computer bus

On Nov 19, 2017, at 11:54 PM, Chuck Guzis via cctalk wrote: > So we agree on parallel standard buses, that STD bus is a strong > contender with varied processor base. Catching up late, sorry if this is an old question, but what did the Digital Group computers

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/20/2017 01:52 AM, alan--- via cctalk wrote: > > If you ever look at how interrupts are implemented on STD bus, you'll > run in fear.  There are only two options, chain the slot to slot > interrupt line (assuming all slots are filled downstream of the CPU) > and share the one request signal -

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 10:51 PM, Eric Smith wrote: > On Nov 19, 2017 7:18 PM, "allison via cctalk" > wrote: > > The rest is the specific implementation.  What happens if the CPU is > 1802 or something else that does not match the 6500 or

Re: Ideas for a simple, but somewhat extendable computer bus

If you ever look at how interrupts are implemented on STD bus, you'll run in fear. There are only two options, chain the slot to slot interrupt line (assuming all slots are filled downstream of the CPU) and share the one request signal - implementing any CPU-specific interrupt requirements

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 08:11 PM, Ken Seefried via cctalk wrote: > More importantly, the vast number of compatible I/O cards that were > produced. Much alternative history to be pondered. So we agree on parallel standard buses, that STD bus is a strong contender with varied processor base. There *is*

Re: Ideas for a simple, but somewhat extendable computer bus

I've always thought STD-Bus missed a real opportunity here. Small enough to be cost effective (relative to the size of, say, S-100 (bonus, no stupid power supply issues)), sane, flexible enough bus structure that I believe there are at least CPU cards using: - 4004/4040 (pre-standard?) -

Re: Ideas for a simple, but somewhat extendable computer bus

On Nov 19, 2017 7:18 PM, "allison via cctalk" wrote: The rest is the specific implementation. What happens if the CPU is 1802 or something else that does not match the 6500 or 8080z80 models. There is nothing that prevents either the serial or parallel arbitration

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 08:54 AM, Noel Chiappa via cctalk wrote: > > From: Allison > > > simple 16 data, 24 address likely 6 lines for basic control plus others > > your up to 50+ lines > > I would seriously consider shared data/address lines, like on the QBUS. It > doesn't add _that_ much

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 03:43 PM, Eric Smith via cctalk wrote: > On Sat, Nov 18, 2017 at 10:48 PM, Jim Brain via cctalk < > cctalk@classiccmp.org> wrote: > >> Looking at the schematic for the ECB, I cannot find any description of the >> signals BAI, BAO, IEI, and IEO. Can anyone shed some light on the

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/18/2017 5:57 PM, Eric Christopherson via cctalk wrote: On Fri, Nov 17, 2017, ben via cctalk wrote: On 11/17/2017 6:59 PM, Chuck Guzis via cctalk wrote: On 11/17/2017 05:34 PM, Jim Brain via cctalk wrote: It does not have to be fast.  I rather thought, "what is the simplest multi-cpu

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 2:43 PM, Eric Smith wrote: Similarly for how the card deals with interrupts, but using the IEI and IEO as the daisy chain. Thanks for the context.  I think the fact that !BUSAK is present on A31 threw me

Re: Ideas for a simple, but somewhat extendable computer bus

On Sat, Nov 18, 2017 at 10:48 PM, Jim Brain via cctalk < cctalk@classiccmp.org> wrote: > Looking at the schematic for the ECB, I cannot find any description of the > signals BAI, BAO, IEI, and IEO. Can anyone shed some light on the function > of these signals? > Bus Acknowledge In and Out,

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/19/2017 9:08 AM, emanuel stiebler wrote: On 2017-11-18 23:48, Jim Brain wrote: > Looking at the schematic for the ECB, I cannot find any description of > the signals BAI, BAO, IEI, and IEO.  Can anyone shed some light on the > function of these signals? Here again:

Re: Ideas for a simple, but somewhat extendable computer bus

On 2017-11-18 23:48, Jim Brain wrote: > Looking at the schematic for the ECB, I cannot find any description of > the signals BAI, BAO, IEI, and IEO. Can anyone shed some light on the > function of these signals? Here again: https://en.wikipedia.org/wiki/Europe_Card_Bus I have some ECB

Re: Ideas for a simple, but somewhat extendable computer bus

> From: Allison > simple 16 data, 24 address likely 6 lines for basic control plus others > your up to 50+ lines I would seriously consider shared data/address lines, like on the QBUS. It doesn't add _that_ much complexity to share the lines (I did a slave device using only 74xxx

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/18/2017 1:46 AM, emanuel stiebler wrote: On 2017-11-17 18:11, Jim Brain via cctalk wrote: I'm currently working on a single board computer system, designing from scratch partially as an education experience, and also as something that might be of interest to others. I've laid out the

Re: Ideas for a simple, but somewhat extendable computer bus

On Fri, Nov 17, 2017, ben via cctalk wrote: > On 11/17/2017 6:59 PM, Chuck Guzis via cctalk wrote: > > On 11/17/2017 05:34 PM, Jim Brain via cctalk wrote: > > > > > It does not have to be fast.  I rather thought, "what is the simplest > > > multi-cpu shared bus that could be easily understood by

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/18/2017 1:46 AM, emanuel stiebler wrote: On 2017-11-17 18:11, Jim Brain via cctalk wrote: I'm currently working on a single board computer system, designing from scratch partially as an education experience, and also as something that might be of interest to others. I've laid out the

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 07:11 PM, Jim Brain via cctalk wrote: I looked at home computer busses (Atari, Apple, Commodore, Tandy, TI) for a bit of inspiration, but they all seem overly simplistic (not horrible, but hate to just punt on the idea). Is the multi-CPU stuff important initially? If not then

RE: Ideas for a simple, but somewhat extendable computer bus

p.org> > Subject: Re: Ideas for a simple, but somewhat extendable computer bus > > On 2017-11-17 18:11, Jim Brain via cctalk wrote: > > I'm currently working on a single board computer system, designing > > from scratch partially as an education experience, and also as > > so

Re: Ideas for a simple, but somewhat extendable computer bus

If you need simple arbitration, there is always this: https://www.retrotronics.org/arbiter/ -Alan On 2017-11-17 20:11, Jim Brain via cctalk wrote: I'm currently working on a single board computer system, designing from scratch partially as an education experience, and also as something that

Re: Ideas for a simple, but somewhat extendable computer bus

On 2017-11-17 18:11, Jim Brain via cctalk wrote: I'm currently working on a single board computer system, designing from scratch partially as an education experience, and also as something that might be of interest to others. I've laid out the first version of the SBC, and I realize it would

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 06:33 PM, ben via cctalk wrote: > Say USB-version 101101100 :) No, I'm serious--lowers parts count tremendously. I run SPI at 40 MHz. But for something simpler in a parallel bus there's always STD bus, or STD-32. --Chuck

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 08:11 PM, Jim Brain via cctalk wrote: > I'm currently working on a single board computer system, designing > from scratch partially as an education experience, and also as > something that might be of interest to others. > > I've laid out the first version of the SBC, and I realize

Re: Ideas for a simple, but somewhat extendable computer bus

On Fri, Nov 17, 2017 at 5:11 PM, Jim Brain via cctalk wrote: > I'm currently working on a single board computer system, designing from > scratch partially as an education experience, and also as something that > might be of interest to others. > > I don't know how complex

Re: Ideas for a simple, but somewhat extendable computer bus

On 2017-11-17 8:55 PM, Jon Elson via cctalk wrote: > On 11/17/2017 07:34 PM, Jim Brain via cctalk wrote: >> On 11/17/2017 7:25 PM, Paul Koning wrote: >>> >>> One key question is whether it should be asynchronous, as the Unibus >>> is, or synchronous. >> I thought synchronous would make for a

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 6:59 PM, Chuck Guzis via cctalk wrote: On 11/17/2017 05:34 PM, Jim Brain via cctalk wrote: It does not have to be fast.  I rather thought, "what is the simplest multi-cpu shared bus that could be easily understood by folks and allow them to focus on multi-processing education,

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 05:34 PM, Jim Brain via cctalk wrote: > It does not have to be fast.  I rather thought, "what is the simplest > multi-cpu shared bus that could be easily understood by folks and allow > them to focus on multi-processing education, not bus understanding" How about a serial bus?

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 07:34 PM, Jim Brain via cctalk wrote: On 11/17/2017 7:25 PM, Paul Koning wrote: One key question is whether it should be asynchronous, as the Unibus is, or synchronous. I thought synchronous would make for a smaller/simpler design, but could be wrong. A synchronous version of

Re: Ideas for a simple, but somewhat extendable computer bus

On Nov 17, 2017 8:34 PM, "Jim Brain via cctalk" wrote: > > On 11/17/2017 7:25 PM, Paul Koning wrote: >> >> >> One key question is whether it should be asynchronous, as the Unibus is, or synchronous. > > I thought synchronous would make for a smaller/simpler design, but

Re: Ideas for a simple, but somewhat extendable computer bus

On 11/17/2017 7:25 PM, Paul Koning wrote: One key question is whether it should be asynchronous, as the Unibus is, or synchronous. I thought synchronous would make for a smaller/simpler design, but could be wrong. A synchronous version of the Unibus would be quite easy; all the funny

Re: Ideas for a simple, but somewhat extendable computer bus

> On Nov 17, 2017, at 8:11 PM, Jim Brain via cctalk > wrote: > > I'm currently working on a single board computer system, designing from > scratch partially as an education experience, and also as something that > might be of interest to others. > > I've laid out the

Ideas for a simple, but somewhat extendable computer bus

I'm currently working on a single board computer system, designing from scratch partially as an education experience, and also as something that might be of interest to others. I've laid out the first version of the SBC, and I realize it would cost nothing to add an edge connector on the PCB,