1090 Development Boards

[reifsnyderb]

A discussion came up about 1090 development boards.  Presently, there are two development/prototype boards designed.  The first prototype board is basically a sea of holes for installing various components that is, essentially, a re-make of Atari's original board.  The second is a breadboard type design that has 3 rows whereby if a chip is installed properly, each of it's pins has a small row of holes that can be used.  There is an interest in development boards with a suggestion that some logic be included as well so as to simplify the development. 

 

This could be accomplished by modifying the design of my firmware board and incorporating that within a section of a development/prototype board.  Because of this, I modified the firmware board schematic such that it's decoders could be used for practically any address, the device enable latch is separate and available, Phi2 Short is broken out, the ROM could be configured for banking, an IRQ could be generated, and the second decoder can have up to 5 latches set if so desired.  (See attached .pdf)

 

Is there a preferred board design?  Would the breadboard version be preferred or the sea of holes?  Any other thoughts on this?

 

Edit to add:  It probably would hurt to utilize the space more efficiently on the board and have a region, near the back (right side in the pictures below), that is easy to add connectors. 

 

Thanks!

 

Brian

 

1090 SD Board.pdf

 

 

 

 

 

 

Edited January 21 by reifsnyderb

[Geister]

Sorry for a stupid question, but I don't notice much difference  between the boards.  Does one of the boards have the ability to host a prototype experimenter's board so that chips can be inserted and removed easily while jumper wired can be inserted and moved as needed, or, are you remaking your board to emulate that functionality?

I'm assuming the "sea of holes" board is a wire wrap design where you insert wire wrap sockets and do your own point to point wiring. 

Most of my early experimenting was done with wire wrap, so I'm comfortable with that.  The prototype board design means that fewer chips can be installed and like Ben Eater's prototypes, you need additional boards to expand the design past three or four chips.  In an uncased system you can use dupont connectors to add external prototype boards, but I'd be worried about unintentional noise.

For the prototype board I'd have to see the bace of the board to see how many additional holes are pre linked to each pin.

Also, how much space does the preconfigured decoding, etc., require on the board design?  I think it's necessary for those that need a leg up on the decoding, but I'd like to see how much realestate would be required

[reifsnyderb]

5 minutes ago, Geister said:

Sorry for a stupid question, but I don't notice much difference  between the boards.  Does one of the boards have the ability to host a prototype experimenter's board so that chips can be inserted and removed easily while jumper wired can be inserted and moved as needed, or, are you remaking your board to emulate that functionality?

I'm assuming the "sea of holes" board is a wire wrap design where you insert wire wrap sockets and do your own point to point wiring. 

Most of my early experimenting was done with wire wrap, so I'm comfortable with that.  The prototype board design means that fewer chips can be installed and like Ben Eater's prototypes, you need additional boards to expand the design past three or four chips.  In an uncased system you can use dupont connectors to add external prototype boards, but I'd be worried about unintentional noise.

For the prototype board I'd have to see the bace of the board to see how many additional holes are pre linked to each pin.

Also, how much space does the preconfigured decoding, etc., require on the board design?  I think it's necessary for those that need a leg up on the decoding, but I'd like to see how much realestate would be required

Both boards are mostly similar and the second board was made by modifying the first board.  The first board is the "sea of holes" board that is probably a wire wrap design.  The second board has the holes connected like a breadboard and certain holes are connected just like a breadboard.  The tradeoff is you could put fewer chips on the second board.  The boards are distinguishable by the silkscreen.  It's probably better to enlarge both pictures so as to tell the difference.  The second board has the rows and columns labeled like a breadboard.

 

I estimate the preconfigured decoding will take no more than 1/4 of the space on the board.  This section of the board should probably be located on the lower left so as to keep it's used space to a minimum. 

 

My current thought is to place the decode/latch/irq logic on the lower left of the board.  The upper left will be mostly the same as it will contain the voltage regulator and a place for the shunt resistor.  The far right should have a sea of holes section that is about 1.5 inches (40mm) from the right edge so it could be cut or modified for a connector.  The physical size of the +5/GND/+12/-12 electrical busses should be reduced and moved closer to the edges of the board as they don't need to be so large and it will make more space for chips.  Also, it may be a good idea to swap out the +5vdc voltage regulator with an SMD voltage regulator as it's pretty much a given that a +5vdc voltage regulator would be used.  The voltage regulator heat sink could be integrated with the board so as to make it easier to use.

 

 

 

 

 

 

[reifsnyderb]

Ok, the big white rectangle is an estimate of how much space the logic would take up.  I figure two voltage regulators, with integrated heat sinks, could be installed above the logic section.  The rest of the board could be used for whatever capability you'd like to develop.  i.e.  SCSI controller, parallel printer port, video card, etc.

 

I figure the power bus sections don't have to be so big and the right side should have an area that could be used for connectors.  So, more space could be created for chips and other components.

 

If enough people are interested in a 1090 development board, that has the Atari interfacing circuitry added, I'll build it.   🙂

 

Edited January 22 by reifsnyderb

[Geister]

Well Brian, 

 

I'll give you a first vote.  Would it help to use surface mount parts to keep that size down?

 

What are the voltage regulators for?  Are you going to feed the 9V AC  directly to the cards?  I was thinking that the regulator was for a 3.3V step down for modern parts.

 

Michael

[reifsnyderb]

14 minutes ago, Geister said:

Well Brian, 

 

I'll give you a first vote.  Would it help to use surface mount parts to keep that size down?

 

What are the voltage regulators for?  Are you going to feed the 9V AC  directly to the cards?  I was thinking that the regulator was for a 3.3V step down for modern parts.

 

Michael

The logic uses 5vdc and the other voltage regulator could be used for your circuit.

 

10vdc (unregulated..could be as high as 14volts or as low as 8 volts or so) is supplied to the cards.  So each card needs at least one voltage regulator.  Some of the components are surface mount.  The PLC's are through-hole so they are easy to program.