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USB on an 8 bit ISA Bus, it is possible!!!

Wow with "256-byte internal SRAM buffer", that's not much for these old computers. Ethernet with a buffer that low already causes problems when other hosts try and send data to an 8088 based machine because they communicate too fast (10mbps). With USB 1.1 devices, I see comparable problems unless that buffer is larger.
 
SRAM is single cycle access.

USB data packets are at most 1024 bytes in size. Having 256 bytes of high speed SRAM does not sound like a horrible mismatch.
 
Also, an 8-bit USB stack, if you limited the drivers available to the most basic, is eminently doable. It's been done (twice!) on the 16/32 bit Amigas.

- Alex
 
I find this thread very confusing. Is the idea to support a USB device on an ISA bus? Well, if you can limit your subset, the FTDI Vinculum looks to be a low-software approach, but what it supports is pretty limited. There are plenty of USB-capable (host mode) MCUs, some with 5V tolerant inputs, e.g. STM32F1xx that are both cheap and quite flexible.

But supporting a generalized USB stack in an 8-bit PC is not something I'd have nightmares about implementing. But a few devices, I don't see an issue.

As far as SD card support, heck, you don't even need an MCU--an SPI interface can be implemented in random logic or even a CPLD and will do just fine if you're not speed-fussy.
 
hello
I did buy a rs232 to USB device :
http://www.sureelectronics.net/goods.php?id=1135
..but have not tried it out jet :eh:
Think it could bee cool to use USB sticks with the old 5150!
But it needs some kind of programming, to make it work in like DOS enviroment.
A first try i will use a terminal application, to communicate with the box.
/cimonvg
 
http://bretjohnson.us/source/source.htm

Bret Johnson wrote a few USB drivers for DOS in the past... they only work on UHCI machines however. Although it requires a 386, they will run in real mode. So it's certainly possible. The comments indicate that the drivers can tolerate a machine which lacks a PCI BIOS as well.

I have successfully used mass storage with Bret's USB drivers, but it's slower than floppy disk access on a 300MHz machine! Never tried the mouse or keyboard drivers. I don't imagine that getting a USB keyboard to hook IRQ 1 would be feasible either, since the PC doesn't send out that interrupt pin to the ISA bus.
 
eeguru said:
Again chip scale BGAs w/ .4mm ball pitch. Good luck on your HDI boards.
Click to expand...

Going forward, I think BGA is one of the stupidest things ever invented, simply because it's impossible for a human to reliably solder them... we rely waaaaay too much on the machines to do everything for us. What do we do when the machines which place BGA components, which themselves contain BGA components, fail? We're going to byte ourselves in the ass one day with this bootstrapping*...

*Hey, just like the GCC project did, since the original version doesn't exist anymore!.
 
RubberTelly said:
BGA to anything

http://www.advanced.com/
Click to expand...

Those adapters do not solve the fundamental problem with BGA components.

It is relatively easy to find a BGA-48 to DIP-48 socket adapter PCB.

Now, how do you fasten the BGA-48 to the adapter?

That requires a lot of technical skill and specialized equipment like an IR soldering lamp.

If SMT is difficult for many hobbyists then BGA assembly is way out of reach.

Have you ever assembled a PCB yourself? Are you familiar with SMT and/or BGA technology?

Andrew Lynch
 
1. Drill appropriate holes in PCB for BGA Balls to sit in, not through the board, just on top, best off to use a drilling jig for this.
2. Apply solder to Chip side of board holes to slightly fill them, do not over do it with the solder, the balls need somewhere to sit.
3. Solder the chip into place by applying a small amount of solder to the Back side of the PCB, enough to melt the front Solder to grip the Balls.
4. Get lots of practise at this, it's easy in theory, but hard to do...
 
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