Fleysher.wbst@XEROX.ARPA (10/01/84)
From: Dan Fleysher <Fleysher.wbst@XEROX.ARPA> Exchanging home-brew BASIC programs within messages over the net requires a modem and a good upload terminal emulator program (such as ATERM, distributed on the net in Oct. '82). Even with this set up, plenty of information can get lost in the transmission - e.g., inverse-video and graphics characters. Sometimes these are crucial when the BASIC program contains machine language assist in the form of text strings (rather than data statements). I have written a pair of companion BASIC programs which enable the exchange of arbitrary files over the net with no loss of data. This is accomplished by converting the file to be sent into a text file containing hexadecimal characters, two for each byte of the original file. One of the programs does the conversion to hexadecimal format, and the other converts the received hex file back into its Atari-useable form. Before I publish these two programs, I would like to invite agreement/disagreement on a standard format for exchange. The format I propose is: -------------------- message header, explanatory text, and general comments .START. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxx .STOP.nnnnn optional extra text -------------------- The translator for the received program ignores all text until it encounters the record ".START." Subsequent records contain hexadecimal characters (x's, above) in convenient (although unspecified) record lengths. The receiving program translates the hex characters into bytes until it encounters the .STOP. record. The number that follows ".STOP." is a decimal checksum, computed by adding up all the preceding bytes encoded as hex characters. (The checksum limit of 10 digits corresponds to a file length of more than 78 megabytes of average data) My programs use record lengths of 36 hex characters so that they fit easily on the 40 character screen. Although the programs are written in Atari BASIC, there is no reason they could not be re-implemented as machine language programs (for speed). These could also be distributed to the net using this facility. Needless to say, this facility is proposed for exchanging PERSONAL or public-domain software only. Opinions anyone? Dan
dunkelbe@ecn-ee.UUCP (10/06/84)
<make my day...>
This sounds strangely similar to any of the loader formats
produced by cross-assemblers. They (I know of Intel, Motorola,
and a 6502 spinoff) usually start with a pre-designated character
(':' for Intel), followed by destination address of rest of data,
length of record, the actual data, and a checksum (I may have
the order transposed). All the information is xmitted in hex
aside from the attention character.
It might be nice to use some format which is a kind of standard.
Besides, I have machine language loaders for my C64 homebrew
terminal emulator which use all these formats...
Kirk Dunkelberger
pur-ee