Interested in USB for TURBOchannel (slhci at tc)?

[Felix Deichmann <m4j0rd0m0%gmail.com@localhost>]

Hi,

tinkering with a Lattice CPLD break-out board and a Waveshape SL811HS 
USB board showed success: I was able to interface the SL811HS and 
TURBOchannel of my DEC 3000/400. Code for "slhci at tc" was easy, as the 
slhci driver seems mature (and portable) already.
The CPLD features a TC interface up to 25 MHz, is capable of I/O 
transactions and interrupts, and even contains a basic option ROM as 
required by TC systems' firmware.
It is a horribly "flying" lab setup with single wires between all the 
connectors at the moment (hardly stable of course, but sometimes :)), 
but I plan to design a "real" TC option module with custom PCB and even 
bulkhead for myself (and others if interested) which will solve all 
stability problems I hope.

Do not expect it to be fast, SL811HS is a USB 1.1 controller (12 Mbit/s) 
and its 8-bit interface is sub-optimal (and errata-prone). I calculated 
SL811HS peak data rate over an optimal (back-to-back) TURBOchannel to be 
~1.25 MB/s for 12.5 MHz TC systems, and ~2.08 MB/s for 25 MHz systems. 
Actual devices on the bus will show slower results of course.

Is anyone else interested in such a TC-USB option? I could kick-off a 
hobbyist maker project of professionally made modules (you would get the 
assembled thing with parts soldered to a PCB, CPLD programmed and 
bulkhead mounted) then. Costs depend on amount ordered of course, but 
even for prototype/smallest volume I see it far below USD $100. I will 
not earn a single cent. Otherwise I will build manually for myself only.
So please excuse cross-posting to the three TC-capable platforms (pmax, 
alpha, vax). It's a NetBSD special right now :)

More info is and will be available here (doc, pics, code, ...):
http://www.flxd.de/tc-usb/

And the alpha port seems to have really broken bus functions for widths 
<= 4 (dense vs. sparse TC space etc.). I will also come up with a patch 
for that soon.

Comments and suggestions welcome!

Regards,
Felix