11 Apr
2002
11 Apr
'02
4:59 p.m.
You could look at Motorola .S19 files or Intel Hex
files. Both have a lot more overhead than pure binary
but they will definitely solve your problems at the
beginning and end of the tape. I'm certain that
someone has already written this and I think I have an
example in an old Byte maganize. I wrote a binary to
Moto S19 and binary to Intel Hex in VB not because no
one had ever done it before, but so that I was sure I
understood them.
I am in a similar situation; I've been thinking about
a short bootloader you key in that reads the first
64/128/256 bytes of the paper tape starting with the
first nonzero byte (you code it this way), and then
executes it. This code is the .s19/Intel Hex loader
(which is going to be much more complex). Then, you
load your stuff in .s19/Intel Hex. Both code chunx
could be on the same tape, theoretically. This, too,
has been done before.
BTW, I'm working on the Hazeltine. The keytops were
actually PUTTY, not BROWN! I had to polish them
individually with sandpaper and car rubbing compound
but they now look new. Haven't started on the
electronics but am confident that I can do it.
--- Bill Richman <bill_r(a)inetnebr.com> wrote:
I've been doing some web searching and reading the
"TV Typewriter"
book concerning puched tape encoding schemes, and
I'm a bit confused.
I've written a program to punch tape on my PC, and a
short bit of code
to read the tapes on my IMSAI 8080, but there are
some problems.
Since the unpunched tape leader looks just like a
"zero" to the tape
reader, I usually end up with some extra 0's at the
start of my
programs on the IMSAI. Also, I have a feeling that
the tape reader
may "eat" some of the codes if they're things like
X-ON, X-OFF, etc,
although I may be wrong. If I'm going to do
something along the lines
of using two 4-bit values to represent each byte, or
an escape code to
distinguish real 0's from leading blanks, and maybe
include a
full-width (FF) punch every foot or so to allow for
easy folding,
while having the reader software ignore them, I'd
like to follow some
kind of established standard. Can anyone give me
any pointers on
this?
-Bill Richman (bill_r(a)inetnebr.com)
Web Page: http://incolor.inetnebr.com/bill_r
Home of the COSMAC Elf Microcomputer
Simulator, Fun with
Molten Metal, Orphaned Robots, and
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