9 Nov
1998
9 Nov
'98
1:01 p.m.
< Allison Parent resonds:
< > If you're building an elf then 2101, if your doing superElf go for 32
< > 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
I happen to have a few tubes of both 2101 and 5101(cmos).
< In any case, I would decode 7 or 8 upper address bits if I went with
that would make expansion easier.
< 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 JE
< sockets and let the builder pick what to go in the, one 62256 or a coupl
< of 6264's and a 27128, for example.
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.
< 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.
< Me, too. There are a couple ways of implementing expansion, Elf-II comp
< and COSMAC VIP compatible. The VIP used those ubiquitous 44-pin cards.
I have the drawings, manuals and I think the rom dumps for a VIP. That
used a simpler keyboard arrangement. I never had much use for it's video
scheme as I wanted minimally 64x16 text as my prefered mode.
< I was thinking of extras like an area for the 1861 video, or a 2"x4"
< perfboard prototyping area. In any case the Quest design wouldn't
< be that expensive in sufficient quantities, but at q. 25, there's
< a lot of setup charges to amortize over the small run of the boards. A
< least $10 each (~$250 setup / 25 boards). If anyone can direct me
< to a board house that will do a 6"x9" board with ~600 holes, three or
< four sizes, plated through, with minimal setup charges, I'm all ears.
< Unless I get *lots* of interest, I'm only considering a run of 25,
< then that's it. I don't want to have 60 or 70 unsold boards hanging
< around forever.
Can't help on the board house. But the 2x4" proto area is desireable.
Not that I'd use it but is the 1861 even available? I don't have any of
them nor 1854s.
< 40 pin CPU, 2x22 pin RAM, 11 switches, 2x7 pin displays, approx 10 CMOS
< DIP parts x 14 or 16 pins, a handful of diodes and resistors... let's
< say about 350 point-to-point connections, probably more. I breadboarded
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.
< The Quest kit was the base ELF plus a ROM socket and space for primary
< and secondary power supplies. One suggestion for the Elf replica was
< to use a standard 4-pin Molex connector and power it from a discarded
< PC power supply. The Quest Elf kit just had two solder pads for 6.3V A
< or +5V DC. I ran mine from my VIP regulated +5v supply.
I used a stack of AA cells (6 of them and used the regulator), then would
run a long time and was portable.
Allison