9 Nov
1998
9 Nov
'98
10:59 a.m.
< I have been in discussion with some folks about 1802's and the possibili
< of producing a modern PCB for the Popular Electronicss Elf design. Han
< Franke seems to think that there would be some interest in Germany for
< a few units, enough to make me consider burning a board. I would be
< curious to hear what other list members though about price, features, et
< The good news is that Harris still makes the 1802 for less than $10, an
< the TIL311 displays that the Elf calls for are available for less than $
< each, used.
I'd be interested depending on version.
< How authentic should a modern Elf be? Try to use 1822/2101 RAM or use
If your building an elf then 2101, if your doing superElf go for 32k
62256.
< UART? Add an I/O port? Add nothing to the Quest PCB layout? Remove
< nothing? (There was a socket for a 16-pin PROM and room for onboard 780
< regulator as well as optional memory battery backup).
The quest layout was the bare minimum elf. No expandability. I have one
and expanding it is not appealing. An expandable elf would be of interest
to me as I still have one (20 year old) 1802 doing not much.
< How much would anyone pay for such a thing? The PCB would probably com
< as a double-sided, plated thru-hole fiberglass board to the same dimensi
< as the Quest board (I have one to compare it to). It would be in the
< neighborhood of $40-$50, depending on how many extras and the order size
For the quest board that is expensive for the bare board.
< Another question, perhaps more on topic - would this count as a classic
< It could be authentic as far as operation is concerned (toggle switches
< and 256 bytes of accessible RAM), but it would still be on a modern
< board, made recently. In short, does form or function denote "classic"
I'd go with replica.
< Yes, anyone who wants can still breadboard an 1802 together. It's a
< pain. I never would have finished my Elf if I hadn't had the PCB
< to stuff. The Elf99 would be a echo of the former classic, but a
< fully working one.
The base ELF was pretty trivial to build as the parts count was nothing.
< Classic clones, anyone?
Replicas of classics.
Allison
9 Nov
9 Nov
12:13 p.m.
I originally wrote:
< 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.
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.
< UART? Add an I/O port? Add nothing to the Quest
PCB layout? Remove
< nothing? ...
The quest layout was the bare minimum elf. No expandability. I have one
and expanding it is not appealing.
Agreed. I never expanded my Quest Elf. My mentor did, a mature fellow of 16
to my 11 at the time. He shoved in a machined pin wire wrap socket and
took it from there. He built his own 8-bit input port and 8-bit relay
driver output port by breadboarding the standard 44-pin Radio Shack prototype
boards. It worked, but it was non-trivial. I inserted the WW socket, but
never wrapped anything to it.
An expandable elf would be of interest
to me as I still have one (20 year old) 1802 doing not much.
Me, too. There are a couple ways of implementing expansion, Elf-II compatible
and COSMAC VIP compatible. The VIP used those ubiquitous 44-pin cards.
I would rather build in a compromise of universally desired features than
get into the position of making peripheral cards. In practice, I like
addon cards, but when it comes down to a very small production run, I'd like
to keep this to one board. Cards are nice when you have lots of users with
very different needs. With an Elf, beyond an I/O port and serial or video,
what's really necessary? What's so important that it raises the cost a few
bucks for everyone?
< How much would anyone pay for such a thing?
...neighborhood of $40-$50,
< depending on how many extras and the order size
For the quest board that is expensive for the bare board.
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. At
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.
< Yes, anyone who wants can still breadboard an
1802 together. It's a
< pain...
The base ELF was pretty trivial to build as the parts count was nothing.
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,
but never more than about 200 connections, and that was a DEC FLIP-CHIP
module tester for the VIC-20 (dual 6821 PIAs and a single DEC 36-pin
backplane connector).
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 AC
or +5V DC. I ran mine from my VIP regulated +5v supply.
-ethan
8:26 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.
6:46 p.m.
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. < How authentic should a modern Elf be? Try
to use 1822/2101 RAM or use
Better design the circuit to accept standard memories,
ROM's also
preflashed flash chips in place of ROM's as a suggestion.
I am not sufficiently versed in flash chips to consider designing one
in. I am sufficiently well versed to include a 27xx EPROM. It's not
the original 32x8 PROM, but it's close enough.
> 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).
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.
If you'd seen the Elf-II schematic, I don't think you would have responded
that way. I was never suggesting cannibalizing AT keyboards. They are
entirely unsuitable. The original Elf-II has a keypad built up from
individual pushbutton key switches, including several ones that latch
up and down for LOAD, RUN and MEM PROT. The hex digits are latched
through a (then) standard keyboard encoder chip. Most micros of the
day used a software strobe keyboard or a byte-parallel ASCII keyboard.
Neither approach would be suitable on the Elf because it's not running
code at all when it's in loop mode - you, the user, DMA bytes in, one by
one. The keyboard encoder is attached to the data bus through buffers.
It's the only machine I know where the primary peripherals (keyboard and
video) are all DMA.
I was suggesting finding modern parts from a distributor of new or
recycled (surplused) parts. I further suggested that modern replacements
could run as much as $2 or $3 per switch (20 switches - 0 to F, R, L, P
and I). The keypad was seen as an improvement over individual bit
toggle switches, but even then, I saw it as an expensive hurdle that kept
me from building an Elf-II.
-ethan
7:05 p.m.
Ethan wrote:
I am not sufficiently versed in flash chips to
consider designing one
in. I am sufficiently well versed to include a 27xx EPROM. It's not
the original 32x8 PROM, but it's close enough.
There are two kinds of Flash chips; the older kind need a 12V programming
voltage; the newer ones use a single supply. I wouldn't mess with the
former.
Although there are some software complexities, the hardware support needed
for the single-supply Flash parts is simply providing a WE signal, just
like for an SRAM (but on a different pin, IIRC).
Many boards are designed with footprints that can be jumpered for SRAM,
EPROM, or Flash. At this late date, I wouldn't even worry too much about
EPROM.
The most common 8-bit 5V-only flash parts I know of are the AMD Am29F010
(128K*8) and the Am29F040 (512K*8). Either one is obviously overkill for an
ELF clone, but I don't think you can get the smaller ones any longer.
The last time I priced them, the Am29F040 was under $10 in small quantities;
perhaps the Am29F010 might even be under $5.
Cheers,
Eric
10 Nov
10 Nov
2:20 a.m.
Date: Tue, 10 Nov 1998 00:46:47 -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. < How authentic should a modern Elf be? Try
to use 1822/2101 RAM or use
I am not sufficiently versed in flash chips to
consider designing one
in. I am sufficiently well versed to include a 27xx EPROM. It's not
the original 32x8 PROM, but it's close enough.
True, but best to keep things easier and more fun, you need to make
do with current avaiable comonents not relying on used or no longer
made parts. That really crimps anyone's fun if can't find the part
or that part costs more than 10 each aside from CPU's.
If you'd seen the Elf-II schematic, I don't
think you would have responded
that way. I was never suggesting cannibalizing AT keyboards. They are
entirely unsuitable. The original Elf-II has a keypad built up from
individual pushbutton key switches, including several ones that latch
up and down for LOAD, RUN and MEM PROT. The hex digits are latched
through a (then) standard keyboard encoder chip. Most micros of the
day used a software strobe keyboard or a byte-parallel ASCII keyboard.
Neither approach would be suitable on the Elf because it's not running
code at all when it's in loop mode - you, the user, DMA bytes in, one by
one. The keyboard encoder is attached to the data bus through buffers.
It's the only machine I know where the primary peripherals (keyboard and
video) are all DMA.
Yeah, you should had said that "DMA" then I would understood! :-)
Make an design and make it work instead of relying on that no longer
made chip even use PIC or multiple IC's?
I was suggesting finding modern parts from a distributor of new or
recycled (surplused) parts. I further suggested that modern replacements
could run as much as $2 or $3 per switch (20 switches - 0 to F, R, L, P
and I). The keypad was seen as an improvement over individual bit
toggle switches, but even then, I saw it as an expensive hurdle that kept
me from building an Elf-II.
Keypad okay, but the "special" chips that is right now on no longer
made and hard to find is not fun. Make it easier for these following
people. There are many users who prefers to use it to explore
the CPU and program with it instead of hacking at hardware level.
-ethan
Jason D.
email: jpero(a)cgocable.net
Pero, Jason D.
9387
days inactive
9388
days old
5 comments
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participants (4)
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allisonp＠world.std.com -
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