Hi Risciers,
>* Dual or quad UART: gives us important motherboard-based serial ports for
>mouse/terminal/modem.
I heard it once, and would like to bring it out again, will the Zilog SSC
be a better choice? As I remember, it is a dual USART chip, and capable
to do sync and async.
>* Video controller: I'm still for a TMS34010-based solution. Here, the
>problem is mainly software. I think using this chip would help to cut total
>system costs quite remarkably. Steve's probably going to flame me about the
>NSC chip, but I think I prefer this one.
Good enough, but still better to use VRAM as frame buffer for TMS and a
24-bit RAMDAC.
>* Ethernet controller: Providing it's cheap enough, it looks like the NSC
>8390 and it's interface chip might be the right way to go here. If the
>devices are expensive, I'm in favour of leaving this section of the board
>unpopulated.
If we are not going to implement ISA bus, 8390 may NOT be the best choice,
some new LANCE chip should have a much better performance than 8390.
Moreover, 8390 is a rather dumb device, why not using a better chip?
One point I would like to raise, since we aim at PC board form factor,
does anyone think about how to put the ethernet connector on the mother
board and still accessible from a normal PC case? There's a hole near
the rear right hand side for keyboard connector, but no other convenient
opening, how to deal with it, drill a hole on the case?
>* SCSI controller: I think we've pretty much settled on the 53c94? Again, I
>don't have pricing info, but I think it's reasonable. This chip is pretty
>vital to the whole system, and I personally think the 53c94 is the best
>chip for the system.
Is it SCSI-2?
>* Boot EPROM: This is pretty straightforward. How much are we shooting for?
>I'd suggest 64k or 128k - I don't think we can really use much more than
>that. I'd like to have a complete system configuration/testing program in
>this along with the code necessary to read a boot image from SCSI, Ethernet
>and serial interfaces. I am willing to spend quite a lot of time on this to
>make it right <grin>.
Do you mean boot from SCSI device (disk AND tape), Ethernet (bootp and tftp)
and some proprietry serial booting interface?
>* I/O bus: I have personally given up on the idea of an ISA bus. No one
>seems to have come up with an easy and cheap solution to implement one. I
>do like Steve's simple/proprietry 8 bit I/O bus, but I'd prefer not to have
>to have the 3041. I think this interface could be stuck onto the 3730
>relatively easily, and think it would serve all our needs as far as simple
>expansion goes. I really can't think of an ISA-based I/O device that anyone
>would want to add to this system that couldn't also be done with the
>proprietry interface. Again, I'd vote for leaving the I/O connectors
>"unpopulated" if they are a significant cost.
If no ISA bus, then we have to adjust our minimal device list on board,
such as floppy disk controller (much much cheaper than SCSI floppy),
bi-directional parallel port (almost a must), sound support (like 16-bit
stereo AD/DA, FM, PCM).
--
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v Stephen Wong Siu-ming v internet: stephenwong@cuhk.hk v
^ Computer Services Center ^ bitnet : a080700@cucsc.bitnet ^
* Chinese University of * phone : (852) 609-8904 *
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