Re: [cosmacelf] Re: ELF II in a coma....
- From: 64536 <john_crane_97@...>
> Lee,Ah! Glad you got it working. Now you have some memory for expansion. :-)
> Thanks again for the chips. The problem turned out to be
> a faulty A5 chip on the motherboard.
"Excellence does not require perfection." -- Henry James
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
- --- In firstname.lastname@example.org, Lee Hart <leeahart@...> wrote:
> From: 64536 <john_crane_97@...>
> > Lee,
> > Thanks again for the chips. The problem turned out to be
> > a faulty A5 chip on the motherboard.
> Ah! Glad you got it working. Now you have some memory for
> "Excellence does not require perfection." -- Henry James
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-
>Just an update for Lee or anyone else who's following....
1) Ran a few simple programs via hex keypad. The Monitor on the
Giant board works fine. I've been using a Radio Shack CTR-121 Tape
Recorder with TDK "normal position" tapes and it works perfectly.
Even so, I've been experimenting with more modern storage. I tried
an Olympus VN-4100PC digital voice recorder. No good. I have
another one with a better frequency range on order. I'll let you
know how it works.
2) My 4K card was really screwy. I turned out to be a faulty A7
chip; a NOR gate wasn't NORing, so the memory chips never got
3) The Netronics keyboard/video card combo works nice, though slow
at 300 baud. I tested by shorting pins 2 & 3 on the RS232 connector
and got the "TV Typewriter" mode.
4) Currently looking at the Full Basic / EPROM card. I suspect I
have a problem with RS-232 input to the Elf II. I'm relearning
again how difficult tinkering with the elf was back in '79. Lots of
fiddly jumpers everywhere and cryptic instruction manuals. Jumpers
11 and 12 on my Giant Board have a switch (to switch between hex
keypad and terminal). Though the Full Basic manual says you don't
need a switch anymore because the software can compensate. However,
you need to use the hex keypad to tell the monitor to branch to
0003, the start of BASIC. So I do this and I think that's what's
making my RS232 input invisible. I tried switching it back quickly
while it's running, but no go. The RS232 input circuit is pretty
simple. J4 is used, so the only semiconductor used is Q1 a 2N5232
transistor. As luck would have it, I had one in my spares box. I
replaced it, thinking it was the most likely failure. But, it
didn't change anything. Now I'm beginning to wonder if it isn't
some obscure jumper setting somewhere, maybe even on another card,
or the motherboard. It wouldn't surprise me now. :)
I'll keep you posted....
- John just a thought that you may have covered already - when in run mode to
start full Netronics Basic be sure not to press the Input key a second time
after entering 3rd byte of the 000003 branch instruction from the Hex
keypad. The handshake is established from hitting <Return> once on the VID
keyboard or Windows terminal.. This should bring up the Width=32/64?
prompt. Pressing anything else seems to halt the sequence. I've never
manged to persuade the RS232 to run faster than 110 or 300 baud.
From: email@example.com [mailto:firstname.lastname@example.org]On
Behalf Of 64536
Sent: 19 October 2007 07:31
Subject: [cosmacelf] Re: ELF II in a coma....
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