9 Nov
1998
9 Nov
'98
5:26 a.m.
Date: Mon, 9 Nov 1998 18:13:15 -0500 (EST)
Reply-to: classiccmp(a)u.washington.edu
From: Ethan Dicks <erd(a)infinet.com>
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: Elf99 - rebirth of a classic
I originally wrote:
Better use widely available SRAMs like you see on motherboard caches
in DIP packages? One 64K x 8bit chip cost $5 at any speeds low as
15ns but it will work in 400ns cycle time machines.
< I have been in discussion with some folks
about 1802's and the possibili
< of producing a modern PCB for the Popular Electronics Elf design...
< How authentic should a modern Elf be? Try to use 1822/2101 RAM or use
Allison Parent resonds:
> If you're building an elf then 2101, if your doing superElf go for 32k
> 62256.
If I can lay my hands on a quantity of 1822/2101 RAMs, then I agree,
even though they will cost as much as the CPU. The 6264 was a fallback.
In any case, I would decode 7 or 8 upper address bits if I went with
a larger SRAM and allow the user to stick in there what they wanted.
One other suggestion is room for a ROM. I could wire in two or three JEDEC
sockets and let the builder pick what to go in the, one 62256 or a couple
of 6264's and a 27128, for example.
Better design the circuit to accept standard memories, ROM's also
preflashed flash chips in place of ROM's as a suggestion.
The problem with replicating the SuperElf is the keyboard. I have no
idea where to get that chip from (74941?), nor an inexpensive source
for that many pushbuttons (including some latching ones). I can see
the keys coming to $2 to $3 each if bought from a standard vendor.
Make a standard keyboard convertors based on PIC ic to spit out ascii
binary using standard AT and PS/2 keyboards? That is far easier than
trying to scrap already valueable stuff for needed parts and
suitable "old" keyboards is hard enough to find already as is.
$10 dollars keyboard and a $20 worth of that little converter kit is
appealing I think.
Snip!
Jason D.
email: jpero(a)cgocable.net
Pero, Jason D.