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More Hardware Project Ideas

Great Hierophant

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Mar 22, 2006
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I wanted to start a thread for new hardware project ideas rather than take up some other thread. Here is what I would love to have:

A 10-inch or less 8-bit ISA EMS 4.0 compatible board. This board should be able to support up to 4MB of RAM. This can be done in two ways. Number one, use 256x4 DRAMs. Number two, use a 30-pin SIMM connector. The interfacing on the typical boards of the day used standard logic and some custom logic, so the glue should be shrinkable into a standard microcontroller.

If someone is feeling more ambitious, why not extend the concept to add extended memory and 16-bit capabilities as well. In this instance, 4 x 30-pin SIMM slots can give you up to 64MB of RAM (8-bit) or 32MB (16-bit) to play with (each SIMM slot using a 16MBx8 stick.). You could then configure whether the board would be working in an 8 or 16-bit system. In an 8-bit system, only half the SIMM slots would work, giving a maximum of 32MB of Expanded Memory. In an 16-bit system, you could have up to 16MB of Extended Memory and 16MB of Expanded Memory. Of course, this would not work very well for systems much faster than 8MHz.

Finally, I would love to have a box that allows XT keyboards (including IBM Model Ms that may not be 100% XT compatible) to work in the Tandy 1000s that have the unique Tandy keyboard. The scancodes of the Tandy and IBM PC/XT keyboard are the same in most respects, its just that the hardware interface is a little different. Some keycodes (cursor keys, F11 & F12) on a 101-keyboard would need to be translated into the Tandy keycodes for the same keys.
 
Is there any compelling reason to use old technology DRAM?

If it's just the protocol that's a little different, one could certainly take the AT-to-XT keyboard converter project and write some new firmware for it to do whatever you wanted.
 
I really prefer using essentially what they had to work with back in the day. DRAMs are cheap, commonplace and easy to interface. FPM, EDO and SDRAM just seem like overkill for a 8088-286 system.
 
Okay, I understand. I was thinking that modern parts (in spite of being 3 volt) are more readily available, especially on a cost-per-bit basis.
 
What I'd like to see is an inexpensive replacement for all of my failing MFM/RLL drives.

By that, I assume that you'd like to keep your current controller, not replace it. More to the point, what would you be willing to pay for such a gizmo? Anything's possible.
 
By that, I assume that you'd like to keep your current controller, not replace it. More to the point, what would you be willing to pay for such a gizmo? Anything's possible.

If you could make an MFM/RLL(ESDI?) drive replacement module for under $50 that could emulate st419,st506,st225, etc then I'm in. Hell I'd even help with the coding/design. :) That would be awesome for resurrecting old HP, Apple, TRS-80 external hard drives without having to buy a "new" drive that will fail within a year. And it should reduce the load on those aging power supplies. ;)

-Matt
 
I would want replacement for ESDI -disk. They (and MFM-replacements) do exist, but I guess they are _very_ expensive
 
I don't think $50 is a realistic target. $100-$150 (minimum) is more like it, for say, a hard drive of about 100 MB. Here's why.

The input and output of an MFM/RLL drive is a raw signal, sent over differential lines (that's the skinny cable). Since it's the controller that determines what those signals are--and controllers are very different from manufacturer to manufacturer), you'll need to go to a sampling method to recreate the data stream. About the minimum is a 4x sampling of the raw data rate. For MFM, that's 20MHz; for RLL, it's 30 MHz. You're not going to do this with plain TTL-type logic. That means modern programmable logic--probably CPLD or FPGA. There's also an intelligence aspect of this--you'll need a microcontroller to handle the control signals and move the data between a volatile track memory and (I assume) some sort of flash memory.

Given this, I can't see a $50 figure.

On the other hand, $1000 for a 30MB ST412-interface hard drive was considered to be a pretty good deal at one time. :)

Other opinions are welcomed!
 
A drive of about 100 MB for $150-$200 would work for me. At that price I'd by 2 or 3. My machines can only handle 8 heads and up to 1024 cylinders anyway. Even 40MB would work for me. Mine are all MFM data. I would be happy just being able to emulate a single drive (DS0).

And yes, I'd need to keep my current controller (unless anyone wants to do a new controller for a Tandy 6000)...
 
I have 3 MFM/RLL controllers here and each have a different chip: 1010, 2010, 1017 although there really isn't much difference in the chip other that output encoding (RLL/MFM) and cylinder/head count. My HP-IB drives use 1010 and 2010. I'm certain Tandy used 1010 controllers in there boards also.

-Matt
 
You must specialize. My collection of MFM and RLL controllers contains exactly 2 where the main controller chip is in a DIP socket. The WD1006VSR2s that I have for example are all SMT. My OMTI and DTC controllers don't use WD chips, period...and so on.
 
I'd like to see a Floppy controller built into the IDE-XT board :D

Perhaps a universal MFM/RLL controller that can auto detect and low level format these type of drives.

How about a Mono/CGA/EGA -> VGA adapter? A scan converter, there are a plenty out there that go from VGA -> DVI or composite -> VGA, but I have yet to see one that would take a vintage video signal and up it to VGA. Probably would not need to boast a large amount of up scaling, 800x600 would work I'd think.
 
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Chuck: I'm with you. It just dawned on me what your idea is. Sample the data directly from the differential lines (RS422 drivers, TTL level from what I have read) and store the raw data to flash. Then feed the raw data back. You wouldn't even need to see what the data is - basically a logic analyzer with storage.
 
That's it. Get the sample rate high enough (4x should do) and you don't care what the controller is. What with big flash drives, capacity of modern media is certainly no problem.
 
Here's another idea. Several times a year, the problem of the DS1287 real time clock module comes up. While Maxim says that the DS12887 might work, they don't warrant it.

On the other hand, the battery-less DS1685 is compatible with the DS1287 (even has Y2K fixes) and needs only a battery and 32.767 ceramic resonator to be a drop-in replacement.

I was thinking that it might be nice to offer a kit that includes the resonator and a header to plug in an external battery.

The DS1685 is less than $3 each from DigiKey.
 
How about a Mono/CGA/EGA -> VGA adapter? A scan converter, there are a plenty out there that go from VGA -> DVI or composite -> VGA, but I have yet to see one that would take a vintage video signal and up it to VGA. Probably would not need to boast a large amount of up scaling, 800x600 would work I'd think.

That is another good idea, but I feel the scaling should be handled as if the card was a VGA card. By this I mean that all 200 line modes should be double scanned and all 350 line modes should be converted so they appear as they would on a VGA monitor (I believe there are extra black borders compared to other modes).
 
Here's another idea. Several times a year, the problem of the DS1287 real time clock module comes up. While Maxim says that the DS12887 might work, they don't warrant it.

On the other hand, the battery-less DS1685 is compatible with the DS1287 (even has Y2K fixes) and needs only a battery and 32.767 ceramic resonator to be a drop-in replacement.

I was thinking that it might be nice to offer a kit that includes the resonator and a header to plug in an external battery.

The DS1685 is less than $3 each from DigiKey.

Hi Chuck! That certainly sounds like an easy one to do!

What you are describing is basically a shim socket PCB with a battery and a resonator, right?

That should be doable assuming people are interested.

Thanks and have a nice day!

Andrew Lynch
 
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