Elf99 - rebirth of a classic

From: Ethan Dicks <erd_at_infinet.com>
Date: Mon Nov 9 23:58:00 1998

>
> < Allison Parent responds:
>
> I happen to have a few tubes of both 2101 and 5101(cmos).

Lucky you. I have a couple of 1822 (CMOS RCA part) and a few 2101's. I
have not yet found a source of 50 to 100 256x4 2101-compatible SRAMs.
I do have a pile of 2114's, but I'd rather use something else.
 
> Fair idea... However a base quest elf with a 3x5" area of plated hole on
> a .1 grid for protoing would be just as useful.

And easier than a hacked Elf with a bus.
 
> < The problem with replicating the SuperElf is the keyboard. I have no
> < idea where to get that chip from (74941?), nor an inexpensive source
>
> That could be hacked with a pal/gal but then is gets hairy.

I thought of that, but rejected it because I want to keep the project
on a hobbyist level. It's one thing to require a certain CPU; you
can't help that. That's the point of the exercise. I think I _can_
avoid other custom parts.

> I have the drawings, manuals and I think the rom dumps for a VIP. That
> used a simpler keyboard arrangement.

I, too, have the VIP docs. We should compare offline to see if one has
something the other does not.

> I never had much use for it's video scheme as I wanted minimally 64x16
> text as my prefered mode.

Back in those days, I built the TVT-6 but never powered it up because I
never got my hands on a video monitor. I was just a kid, and a $75 to
$150 device might as well have been $75,000 or $150,000 for as little
as I had.

> Can't help on the board house. But the 2x4" proto area is desireable.

Yeah. I got the inspiration from my recent aquisition of a Z-80 Starter
Kit that has a prototype area and two S-100 slots (unfilled).

> Not that I'd use it but is the 1861 even available? I don't have any of
> them nor 1854s.

The 1854 is still in production by Harris. I do not think that the 1861
is available, but it is the "correct" chip to use with the 1802. Anything
else, like a 6845, would be _way_ too much work to be worth the effort.
There is a 1871 keyboard encoder that is still in production. I even
have a small tube. Perhaps that could be a drop-in replacement on an
Elf-II replica. I'll visit the Harris web page and peruse the data sheets.
 
> < 40 pin CPU, 2x22 pin RAM, 11 switches, 2x7 pin displays...
>
> Compared to some of the projects I was doing then that was trivial. Try
> 16k of 2114 (32 of them), 2 2732s, z80, ctc, sio, 765 FDC, plus interface
> logic all on a s100 card.

I was clearly never in your league, but then, I was just a snot nosed
kid with bigger dreams than my pocket book allowed for. At 16, I had
an Elf and a PET and was always pushing them to do more.
 
> I used a stack of AA cells (6 of them and used the regulator), then would
> run a long time and was portable.

That would work. I always wanted a CMOS replacement for the TIL311 displays
so that I could power it off of a lantern battery for virtually forever.
It was the one TTL part on the Quest design.

-ethan
Received on Mon Nov 09 1998 - 23:58:00 GMT