Perry Harrington
Titanium
- Joined
- Oct 7, 2006
- Location
- Klamath Falls, Oregon
Hi all, over in my "little home shop" thread I have been discussing the development of a new memory board for my Fadal 1400-2 based control.
Basically it was a thought experiment that became reality, I designed and built a single memory board that replaces 3 1460-1 memory boards and 1 1460-0 memory board. It's an "All In One" memory board to expand a 1400-1 to 156K of memory and the 1400-2 to 422K of memory.
I've got 3 boards left in my Beta batch that I'm going to build up and offer for Beta testers.
The Beta test will be on a deposit basis, if you decide to keep the board you will get $1000+ of value for a significantly reduced price, but if you have problems and the board doesn't work, you are not out of pocket.
I am confident in my own testing on my 1400-2 control and bench testing the design, but these are Beta quality boards and may have issues, that's the point of Beta testing.
What this is and why it matters:
This is a single board solution that replaces all main-bus memory board SKUs, 1 board is a all-in-one solution to max out the memory of a 1400-1 or 1400-2 control. It uses a single modern memory chip to offer max memory. By my calculations you should never have to replace the Lithium battery, so there is no battery test button/LED (my own 1400-1A board has a 32yo battery that is still good and has 4 chips). The only configuration is a switch block, "UP" position for 1400-2 controls, and "DOWN" position for 1400-1 controls -- no need to wire an address matrix.
Why did I build it?
It was a thought experiment at first, I commented years ago when reverse engineering my 1400-1A board that "I can go to Digikey right now and pick up a 512KB ram chip for $6.44, that’s a heck of a lot easier to interface than 16 separate chips". Well, that thought experiment took over once I got a 1400-2 CPU card, and so I reverse engineered the 1460-0 memory board and then designed a new memory board around that 512KB RAM chip. What drove me in that direction was the 1460-1 memory board having a much reduced parts count, it is very simple. So now I've got 422KB of program memory in my 1400-2 control.
What does it do?
If you have a 1400-2 control, this 1 board replaces 3 of the 1460-1 memory boards. You *only* use this one board.
If you have a 1400-1 control, this 1 board replaces the 1460-0 board. The 1400-1 only supports 1 extra memory board from what I can tell of the firmware. It's possible that later revs of the 1400-1 support more memory, but mine doesn't.
In any use case, this *one* board will give your control the maximum possible memory.
Does it work?
I have run the 1460 memory test in the Diagnostics, and passed. I have run the destructive memory test, which writes data and does checksums to all of the memory, and passed. So I'm fairly confident it is working.
What are the problems you encountered?
There were some timing issues I ran into that I resolved with component changes. Fadal designed the 1460-0 board with all discrete logic and Intel S100 bus drivers, but on the 1460-1 memory board they switched to industry standard bus drivers and used custom logic (GAL) to drive the bus drivers and address logic. At the time of manufacture the GAL they used was $8.80, about 4x the cost of normal IC chips and more expensive than the equivalent decode logic on my memory board. I speculate that they used custom logic because of timing issues with the bus drivers, because it takes a few more gates to make the same effective circuit as the Intel bus drivers. I solved this problem by using faster logic gates, which they also had available back then, but they probably would have been more expensive overall than the GAL. I am reasonably confident, both in empirical testing and static analysis, that I have a working solution, and that's what a Beta test is intended to figure out.
If there is interest in the Fadal community for this board, I may order more and produce them, but only on a pre-order basis, because I anticipate the market is very small.
If you want to participate in the Beta test, please send me a DM (do not create a public post on my profile, because I don't get notified of those).
Basically it was a thought experiment that became reality, I designed and built a single memory board that replaces 3 1460-1 memory boards and 1 1460-0 memory board. It's an "All In One" memory board to expand a 1400-1 to 156K of memory and the 1400-2 to 422K of memory.
I've got 3 boards left in my Beta batch that I'm going to build up and offer for Beta testers.
The Beta test will be on a deposit basis, if you decide to keep the board you will get $1000+ of value for a significantly reduced price, but if you have problems and the board doesn't work, you are not out of pocket.
I am confident in my own testing on my 1400-2 control and bench testing the design, but these are Beta quality boards and may have issues, that's the point of Beta testing.
What this is and why it matters:
This is a single board solution that replaces all main-bus memory board SKUs, 1 board is a all-in-one solution to max out the memory of a 1400-1 or 1400-2 control. It uses a single modern memory chip to offer max memory. By my calculations you should never have to replace the Lithium battery, so there is no battery test button/LED (my own 1400-1A board has a 32yo battery that is still good and has 4 chips). The only configuration is a switch block, "UP" position for 1400-2 controls, and "DOWN" position for 1400-1 controls -- no need to wire an address matrix.
Why did I build it?
It was a thought experiment at first, I commented years ago when reverse engineering my 1400-1A board that "I can go to Digikey right now and pick up a 512KB ram chip for $6.44, that’s a heck of a lot easier to interface than 16 separate chips". Well, that thought experiment took over once I got a 1400-2 CPU card, and so I reverse engineered the 1460-0 memory board and then designed a new memory board around that 512KB RAM chip. What drove me in that direction was the 1460-1 memory board having a much reduced parts count, it is very simple. So now I've got 422KB of program memory in my 1400-2 control.
What does it do?
If you have a 1400-2 control, this 1 board replaces 3 of the 1460-1 memory boards. You *only* use this one board.
If you have a 1400-1 control, this 1 board replaces the 1460-0 board. The 1400-1 only supports 1 extra memory board from what I can tell of the firmware. It's possible that later revs of the 1400-1 support more memory, but mine doesn't.
In any use case, this *one* board will give your control the maximum possible memory.
Does it work?
I have run the 1460 memory test in the Diagnostics, and passed. I have run the destructive memory test, which writes data and does checksums to all of the memory, and passed. So I'm fairly confident it is working.
What are the problems you encountered?
There were some timing issues I ran into that I resolved with component changes. Fadal designed the 1460-0 board with all discrete logic and Intel S100 bus drivers, but on the 1460-1 memory board they switched to industry standard bus drivers and used custom logic (GAL) to drive the bus drivers and address logic. At the time of manufacture the GAL they used was $8.80, about 4x the cost of normal IC chips and more expensive than the equivalent decode logic on my memory board. I speculate that they used custom logic because of timing issues with the bus drivers, because it takes a few more gates to make the same effective circuit as the Intel bus drivers. I solved this problem by using faster logic gates, which they also had available back then, but they probably would have been more expensive overall than the GAL. I am reasonably confident, both in empirical testing and static analysis, that I have a working solution, and that's what a Beta test is intended to figure out.
If there is interest in the Fadal community for this board, I may order more and produce them, but only on a pre-order basis, because I anticipate the market is very small.
If you want to participate in the Beta test, please send me a DM (do not create a public post on my profile, because I don't get notified of those).
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