> But: I think it's time to lay back, cool down and think
> about WHAT DO WE REALLY WANT ?
> Remember, the whole thing started as an ISA card with
> CPU, some RAM and a way to use the rest of a PC as
> I/O subsystem, right ?
> Now we're on the way to build a complete workstation
> with lots of features, on-board intelligent video, scsi,
> ethernet, serial, sound and whatever.
> That all sounds good, but I doubt that all this is really necessary.
But by the time you reach the end of your list you've not only
specified a complete workstation, you're calling it that yourself.
> Things we *do* need and things we *might* need:
> * A CPU. This is a *must* :-). Should be a 3051E, better 3081E.
> They are pin compatible, so the choice is no problem at all.
> If the R4K2 is in fact that cheap: YES ! We should use it.
The only information I have on the R4200 is the announcement from
Byte Magazine that was shared, and that sounded like complete
Vaporware (tm) to me. Impossible power specs and a promised
delivery no sooner than six months in the future? I wouldn't hold
my breath waiting for that one. On the other hand, I _would_ hold
my breath waiting for the IDT3730. That one would reduce the parts
count and increase the probability of getting it working.
> * Ram. The more, the better. Someone suggested to use
> those 36bit by 512k or 2M modules. That saves boardspace,
> right, but they are nearly twice that expensive than four of
> the good old x9 modules.
> I would say, 64 Meg on board is *definitly* enough.
I don't like to give as much board real estate to this as Neill wants,
but you definitely need enough sockets to get the interleave that Neill
wants. 32M (8 pieces, 4M X 9 bits) would probably satisfy me, so as
long as I can leave some sockets empty I won't complain.
> * Keyboard controller. This is a *must*.
This _should_ be pretty easy, but I confess I haven't investigated.
I would expect I could salvage the pre-programmed 8041 from a dead
286PC motherboard and hang it on the 8-bit bus of the IDT3730 with
no more glue than two or three terms from a 22V10. I'll see if I
can find out.
> * Serial I/O. For starting the Linux port, we will need
> two ports; one for a dumb ascii terminal, one for downloading
> Two ports are still sufficient for a workstation:
> One for the mouse, the other one for the modem.
> A third port is an *option*. It could be used for a printer
> in case we don't have a parallel port.
Agree, but I'd really be disappointed if I couldn't make one of
those ports run at least 38400Kbits/sec. My primary network
connection would be a V.32bis/V.42bis modem, as this thing would
reside in my spare bedroom.
> * Parallel port. This is also an *option*. It might be
> cheaper than a third serial line. Take a LS374 and one GAL
> and the printer port is ready.
Agree. When the board real estate gets tight this connector gets
> * SCSI. This is a *must*.
> I can't imagine a workstation without SCSI...
Here is where you start calling it a workstation. Actually, I
agree. SCSI is the _most_ important I/O to me.
> * IDE. This is an *option*.
> We do not really need it, although it would make the
> complete machine cheaper.
If you're buying a new disk drive, the difference is negligible. I
don't have any IDE disk drives lying around, maybe others do. If
you're buying a tape drive or a CD-ROM drive SCSI is certainly
preferable, and I don't think we have room for the connectors for
> * Ethernet. This is a *must*. We can't call the thing
> "workstation" if it doesn't have an ethernet port.
I'd like to have it, but I could live without. As I said, my
primary network connection would be a modem.
> * Real time clock. This is a *must* too.
This should be cheap enough and small enough that it goes without
saying. A computer that doesn't know what day it is is pretty
stupid. I said that over twenty years ago.
> * Video on board. Don't laugh, but this is an *option*.
> * Color graphics on board. I'd say, this is even more an *option*.
> * Intelligent video on board. This is definitly an *option*.
A dumb frame buffer on board, 8 bits per pixel, with no multiple
scan frequencies (pick one when you buy the crystal). That's high
enough on enough people's wish lists to justify. The parts count
and board space don't seem too much to me.
> * Sound I/O. This is an *option*.
I don't care at all. I wouldn't give much board space to it.
> * ISA Bus... I would say: we *do* need exactly one slot.
> Every slot more is an *option*. Why ?
> Ok, my idea is the following: We design the complete
> machine, preferably without any video stuff. I could imagine
> that we provide a simple dma channel for monochrome video
> with a resolution and timing which a standard VGA monitor
> can handle. But even this is not really necessary.
> And we provide exactly one ISA slot for an off-the-shelf
> VGA card. No provisions for dma, bus master stuff, no
> 8/16 bit detection and all that. That ISA slot must provide
> all signals necessary for controlling a VGA card and
> nothing else.
The no DMA, no bus master, no 8/16 bit detection are good ideas
worth discussing. The original PC/XT bus was simple enough you
could probably implement it with a couple of 22V10's and the
IDT3730. In that case, it would make more sense than an ad hoc
expansion bus that has no market.
Of course, I'm only guessing about the capabilities of the IDT3730.
Sure would like to have a data book for that!
Ted Spradley Recognition International, Inc. Opinions are mine, not theirs.
2701 E Grauwyler Rd. |Your productivity is not enhanced when you're staring
Irving TX 75061 |at that thing. Your productivity is enhanced when
214-579-6692 |the computer is working and you're doing something else.