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Re: More ramblings...

To: SMACKINLA@cc.curtin.edu.au (Pat Mackinlay)
Subject: Re: More ramblings...
From: Stephen Siu-ming Wong <a080700@hp750a.csc.cuhk.hk>
Date: Sun, 27 Jun 93 22:07:00 HKT
Cc: riscy@pyramid.com
In-reply-to: <01GZVM88DN3EFUMJ82@cc.curtin.edu.au>; from "Pat Mackinlay" at Jun 27, 93 4:32 pm
Mailer: Elm [revision: 70.30]
Hi Risciers,

>* Dual or quad UART: gives us important motherboard-based serial ports for 

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 

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).

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       *
v Hong Kong                v fax     : (852) 603-5001       v


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