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DIY S-100 BUS System

T

TandyMan100

Veteran Member
Joined
Jan 7, 2009
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At my computer
Hey,

I'm new to the forums, and was wondering if anyone new anything about DIY S-100 systems. Schymatics, parts lists, where to find parts, etc. would be nice.

It's for a 4-H project. ;-)
 
Are you talking about building up a system from scratch? That is, your own PC boards, backplane, etc.?

If so, I'd suggest something a little more modest, such as Andrew Lynch's Z80 setup. Not S100 bus, but gets the job done.

Or look at STD Bus--fewer signals to deal with and just as veneered and generated as S100.
 
I'll add that Andrew's setup makes more sense from a modern DIY standpoint. It still uses a vintage Z80 without the bother of older low-density or hard to get (or hard-to-interface) components, such as 3-supply UARTS or MOS DRAM.

On the other hand, if you have access to a bunch of S100 boards and only need to build a backplane and power supply, that's a different matter entirely.
 
Chuck(G) said:
Are you talking about building up a system from scratch? That is, your own PC boards, backplane, etc.?

If so, I'd suggest something a little more modest, such as Andrew Lynch's Z80 setup. Not S100 bus, but gets the job done.

Or look at STD Bus--fewer signals to deal with and just as veneered and generated as S100.
Click to expand...

That would work, but I can't find any complete schematics, that is, the whole computer on one page. They are all split up and I can't make heads or tails of them. Basically, schematics and a parts list like the Small TV Terminal (google it), and I have a <$50 budget. I was going to build the TV Terminal, but I don't have a programmer for that or the money to get one.
 
Andrew's offering a very good deal if that's the case.

Heck, go for it and I'll even throw in a 4MHz Z80 to get you going. I may even have a 16C550 or two wandering around in my hellbox (Are Z80 DARTs that hard to find now? ).
 
I've got a pile of Z80 type chips somewhere; don't know if there are any DARTs left though. If I find 'em I'll post here in case anyone needs any.
 
MikeS said:
I've got a pile of Z80 type chips somewhere; don't know if there are any DARTs left though. If I find 'em I'll post here in case anyone needs any.
Click to expand...

Andrew's design takes 16C550s; I was just wondering why he used the 8255 and 16550 rather than the more traditional Z80-PIO and DART/SIO chips.

Must be getting hard to find. The DART/SIO chips give you two channels, the 16C550 only one. Can you use an 8274 in place of a DART?
 
patscc said:
I thought there weren't anymore pcb's for the cpu board available ?
Or am I confusing it with something else ?

patscc
Click to expand...

Hi! No that's not true, I have *many* PCBs available for builders -- whole box full! If anyone wants to join the N8VEM project, especially the original poster, please contact me and I will help you as best I can.

I noticed my supply of the SBC PCBs was starting to get low after a burst of interest and so I reordered a new batch and hopefully I timed it right to avoid any delays. In any event there are lots of PCBs available and more on the way.

There are four kinds of PCBs in my stash here. The four available right now are; the SBC, the ECB bus monitor, the ECB backplane, and the ECB prototyping board.

The Disk IO board just went to manufacturing a few days ago and should be available by end of January. Of course that will be its debut so it might be appropriate for the more experiences, dedicated, and/or adventuresome builders since there is always that "pioneer risk" that the other boards which have more proven track records. I am not saying any are perfect but at least we have evidence they work!

If anyone has any questions I will be glad to answer them here. All the N8VEM information such schematics, PCB layout, software, etc is freely available and publicly posted. If people are having problems finding the information I need to know that so I can improve the wiki and mailing list.

I designed the N8VEM project to be low cost and scalable. It can be built using common TTL chips including electronic scrap components. Some I have a list of "minimum" components necessary for the absolute least system possible that will still function.

Thanks and have a nice day!

Andrew Lynch

PS, I've been AWOL on N8VEM the last couple of days because I am trying to give Hargle's 8 bit IDE project a bit of a boost. I am not ignoring anyone just a bit overloaded at the moment.
 
Chuck(G) said:
Andrew's design takes 16C550s; I was just wondering why he used the 8255 and 16550 rather than the more traditional Z80-PIO and DART/SIO chips.

Must be getting hard to find. The DART/SIO chips give you two channels, the 16C550 only one. Can you use an 8274 in place of a DART?
Click to expand...

Hi Chuck! Yes, the design choice to use 16550 UARTs has been a bit of a controversy but I did it to allow a simple low cost implementation. 16550's are plentiful common chips you can get for less than $3 in many places. The design also allows 8250 and 16450 chips to be used. The idea was to use low cost electronic scrap for a minimum capability low cost system.

I can't argue the Zilog Peripherals are not more capable but those can be phased in as a separate optional board if they are needed or wanted for a special purpose. Right now I am building a prototype with the CTC, DART, and dual PIOs on it for the N8VEM builders which should settle this issue hopefully. The 16550/8255 will still be one the SBC and usable so they aren't lost.

Trying to keep the costs low and design robust/scalable etc is a balancing act that results in sometimes less than optimal choices to keep the overall system in balance. IMO, adding a suite of Zilog Peripherals to the SBC would have driven complexity and PCB size (and cost) up significantly.

Thanks and have a nice day!

Andrew Lynch
 
lynchaj said:
Hi! No that's not true, I have *many* PCBs available for builders -- whole box full! If anyone wants to join the N8VEM project, especially the original poster, please contact me and I will help you as best I can.

I noticed my supply of the SBC PCBs was starting to get low after a burst of interest and so I reordered a new batch and hopefully I timed it right to avoid any delays. In any event there are lots of PCBs available and more on the way.

There are four kinds of PCBs in my stash here. The four available right now are; the SBC, the ECB bus monitor, the ECB backplane, and the ECB prototyping board.

The Disk IO board just went to manufacturing a few days ago and should be available by end of January. Of course that will be its debut so it might be appropriate for the more experiences, dedicated, and/or adventuresome builders since there is always that "pioneer risk" that the other boards which have more proven track records. I am not saying any are perfect but at least we have evidence they work!

If anyone has any questions I will be glad to answer them here. All the N8VEM information such schematics, PCB layout, software, etc is freely available and publicly posted. If people are having problems finding the information I need to know that so I can improve the wiki and mailing list.

I designed the N8VEM project to be low cost and scalable. It can be built using common TTL chips including electronic scrap components. Some I have a list of "minimum" components necessary for the absolute least system possible that will still function.

Thanks and have a nice day!

Andrew Lynch

PS, I've been AWOL on N8VEM the last couple of days because I am trying to give Hargle's 8 bit IDE project a bit of a boost. I am not ignoring anyone just a bit overloaded at the moment.
Click to expand...

I would be the original poster. The project is for 4-H electrical. My instructor and I made a bet that I could not build a fully functional (working) computer. What I am looking for is the Backplane and SBC. Does anyone know where to find those plugs that attach to the backplane?
 
Hi!

Yes, there are parts lists on the wiki for all the PCBs. Actually there are several as parts selection is a personal preference.

The ECB backplane uses DIN 41612 connectors and are available from Jameco, Digikey, etc. Just be sure to get the FEMALE, STRAIGHT, PCB MOUNT, DIN 41612 connectors with extra long solder tails. Don't get the regular short ones or they'll be too short and it'll make soldering a real pain.

I recommend for new builders to join the mailing list and post what you would like to do. You can use the parts lists provided or make your own but be sure to post it to the other builders for comments before you order. That'll save you making expensive mistakes in buying parts you don't need or can't use.

The N8VEM builders are a great friendly group of people and are willing to help but you have to ask. I will do my best to help the builders with their projects!

Thanks and have a nice day!

Andrew Lynch
 
So, what OS does the N8VEM use? Is it able to be plugged into say a Tandy Model 100 in TERM mode as soon as it is completed with a null-modem cable? Or does it have to be straight-through? Also, is there some zero-to-hero total n00bs guide to how to get this thing built? I have no idea what all of the stuff on the website means. The parts list I assume is excactly what I should buy from that website, and then I solder it in, but what part numbers correspond with what numbers on the PCB? E.G. xxxx Resistor=R1, xxx Capacitor=C1, etc. This is how I am used to building electronic projects.
 
TandyMan100 said:
So, what OS does the N8VEM use? Is it able to be plugged into say a Tandy Model 100 in TERM mode as soon as it is completed with a null-modem cable? Or does it have to be straight-through? Also, is there some zero-to-hero total n00bs guide to how to get this thing built? I have no idea what all of the stuff on the website means. The parts list I assume is excactly what I should buy from that website, and then I solder it in, but what part numbers correspond with what numbers on the PCB? E.G. xxxx Resistor=R1, xxx Capacitor=C1, etc. This is how I am used to building electronic projects.
Click to expand...

Hi!

The N8VEM SBC runs a RAM monitor and can boot CP/M 2.2. You can connect it to a terminal or PC running terminal emulation software to interact with it. There are instructions on how to build the serial cable on the wiki. Probably the best way to go is to ask on the forum though and depending on what you'd like to do give some guidance as to the best approach.

Uh.. no the N8VEM is a home brew computing project not a kit like an Heathkit H89 or Ramsey radio. You basically have to select your parts and assemble the SBC based on the schematic, PCB layout, etc. There are some step by step guides but no detailed instructions. There are no "zero to hero" guides AFAIK, sorry. The parts lists are guides and the information is guidelines only. The builder is making a home brew computer and too much instruction is actually considered a negative thing because each builder is unique and their machines are all unique as well.

One of our more prolific and talented builders, James, did publish this article which you can find here:

http://www.instructables.com/id/Robot_Brain_Build_a_single_board_computer_in_an_e

Thanks and have a nice day!

Andrew Lynch
 
Sub $50?

This is for replicating something that cost over $2000 in 1980 dollars?

But yes, I think it can be done. I just costed up the 4 port version of the N8VEM and it costs $45 for parts and I got boards made and in bulk they are only $5. Lots of boards around too. Andrew got another batch in recently. I've got lots as well. That price assumed all new components and costed the uart at $7 because here in Australia they are hard to get and by the time you add shipping they are that much. If you are in the US, more like $3.

Re "My instructor and I made a bet that I could not build a fully functional (working) computer."

How much did you bet? More than $50 I hope, and then you can get a free computer *grin*.

Ok, a few caveats here, but *if* you have an eprom programmer and *if* you have a windows PC then you can build a complete computer from scratch. I did it the other night with a stopwatch running. Start with a board, sockets, all the parts and a blank eprom. After 35 minutes, board is built. 4 minutes to get the software for the eprom and program the eprom. You could run hyperterminal at this point and send files over one by one, but I cheated and wrote a vb.net terminal program (on the wiki - all open source) that sends all the files in batch mode. Takes about 4 minutes at 38400 baud. Et Voila - a working computer with CP/M, Wordstar, Mbasic, Sbasic, Supercalc and some fun games. All under an hour.

If you want to take it a bit further, add $15 for a 20x4 LCD, and grab an old PC keyboard and just plug them in and you have a totally standalone computer.

If you don't have an eprom programmer, just ask and someone can program one.
 
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