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Design choice/vote PRELIMINARY

To: riscy@pyramid.com (Mips 3000)
Subject: Design choice/vote PRELIMINARY
From: Bill Broadley <broadley@neurocog.lrdc.pitt.edu>
Date: Wed, 7 Jul 1993 17:17:28 -0500 (EDT)
Reply-to: riscy@pyramid.com
Sender: riscy-request@pyramid.com
I think we need some direction/organization.

I made this list of choices for motherboard design including prices, advantages,
disadvantages, etc.

Once I collect as much informations as possible I plan to put the below list
up for a vote.  So if someone wants X simm slots, or 24 bit color they will 
know how much it will cost etc.  It's alot easier to argue about features
with prices then without.

Please email  corrections, additions, clarifications etc.

My goal if for the costs to reflect board real estate, and all suport chips.
My goal for advantages/disadvantages is to list things like hardware/software
design time, flexibility, usefulness, etc,

I've included some 486 based solutions soley as reference points.

Hopefully once below is filled out we can take a guess at the price +/- 25%


486-size motherboard X layers XxX inches.               $XXX

CPU:   Mips 3081                                        

Mips 3081 40 Mhz 8k I-cache 16 k d-cache + fpu          $300 
Good clean 32 bit risc design, cheap, and integrated from IDT.  Pin compatible 
with cheaper (less cache, no fpu, slower) mips chips.  Faster then 486 for 
INT performance and much faster at FP performance.

80486-66 DX2                                            $510
Few registers, cisc, 4k I-cache 4k d-cache, terrible fp.

IDT 3730  Peripheral controller                         $XXX

Drives ram, parity, 2 dma channels, eproms roms etc.  Greatly simplifies 
design, could help with graphics, another reason to use the above mips 3000.

Sim slots:  How much do you want to pay?  How much do you have room for?

4 simm slots $XXX
8 simm slots $XXX
12 simm slots $XXX
16 simm slots $XXX
20 simm slots $XXX
32 simm slots $XXX 

Conventional 4 MBx 9 simms???                           (yes/no)
Nice for those with ram already.  Although other simms allow 4x density

256k secondary cache?                                   $XXX
Sounds like a good idea especially for the mega-ram people.  Probably could 
make a significant difference, even 12.5 Mhz decstations have 128k caches.

Isa supports                                            $XXX
Allows access to a multitude of cheap pc cards except for use of the MASTER 
signal.  A good choice not for it's technical merit but becuase of whats
available for it.  (Note most high bandwidth items will be on board).
I like this if only for a IDE+floppy+2 serial+parallel for $20

ISA slots:  How much do you want to pay?  How much do we have room for?
2 ISA  slots?                                           $XXX
3 ISA  slots?                                           $XXX
4 ISA  slots?                                           $XXX
5 ISA  slots?                                           $XXX

Custom bus?                                             $XXX    
Cheaper connectors, higher speed, better design. But can only use 
boards we design and build.

Video:  (all benefit the high bandwidth on the motherboard)

Dumb frame buffer + 1 MB of vram                $XXX
2 Mb 1280x1024x8 1024x768x16 possible?          $XXX

All video slows down the main cpu, software support is easy, minimal cost
solution.  Probably worst performance of these choices, but should be ok.

SMT S3 928 + 1 MB vram + dumb frame buffer?     $XXX
2 Mb 1280x1024x8 1024x768x16 possible?          $XXX

Can base work on the S3 X11 server, should be fast, kinda of a midpoint
between dumb frame buffers and a full cpu for graphics.  Very popular
in HIGH end pc video boards.  

A 3041 + 1 MB vram + Ram for 3041 +  dumb frame buffer?         $XXX
2 Mb 1280x1024x8 1024x768x16 possible?                          $XXX

Leaves the main cpu free from running Xserver. More difficult to support in 
software but gcc+mips compatible X-server helps.  Performance should be very 
good.  Probably need at least 2-4 MB for the 3041 to run an xserver.    Better 
use of on-chip cache, less context switches, etc.  Kinda of a xterminal 
on the motherboard hooked up via dma ;-)  

VESA 2 MB S3 801 board                                  $150-$200
Just a reference point from the dos world. For a fast 2 MB card.

Ethernet:  Max bandwidth 1.25 MB/sec (bandwidth alone doesn't justify on board).

On board 16 bit ethernet?                               $XXX
Waldorf want's one.  Cheaper on motherboard.  Probably a good investment.

ISA Western Digital 8003 card?                          $120
8 bit card (slow) price from the mailing list.  Makes motherboard cheaper. 
Makes motherboard+ethernet more expensive.  Drivers available for linux.

Disk interfaces:

On the motherboard SCSI 5 MB/sec                        $XXX
Standard, flexible, cheap on motherboard. 

On the motherboard Fast SCSI 10 MB/sec                  $XXX
More expensive, faster, different drives, still hook up cdroms?

On the motherboard Fast/wide 20 MB/sec                  $XXX
More expensive, faster, needs different Drives, cdrom?

IDE on the motherboard.                                 $XXX
Great for those with IDE disks already

Floppy on motherboard                                   $XXX
Great for boot floppies, or those without net connections/tape backups.

ISA SCSI Future Domain 1680 (16-bit)                    $165
Can't use the ISA master signal, slower, expensive

Small stuff:  
2 Serial ports on board (useful for everyone/debugging)         $XX
Parallel port (Status lights? printers?)                        $XX
2 serial, parallel, floppy+ide on board                         $XX
2 serial, parallel, floppy+ide on ISA                           $20
Audio IN/OUT (to what spec?)                                    $XX

Lights (cpu busy? Heartbeat? disk activity? net activity?)      $XX
Real time clock (not needed if on net.)                         $XX
Keyboard controller                                             $XX


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