Message-ID: <900009@bradley.UUCP>
Date: Thu, 17-Jan-85 23:41:00 EST
Article-I.D.: bradley.900009
Posted: Thu Jan 17 23:41:00 1985
Date-Received: Sat, 19-Jan-85 10:40:37 EST
Lines: 18
Nf-ID: #N:bradley:900009:000:811
Nf-From: bradley!brad    Jan 17 22:41:00 1985

I am looking for any public domain terminal programs for the IBMPC
Jr.  I would like source and in 'C'.   I am also currently trying
to get a program working on it.  The only one so far is PC-TALK,
I have a program but the problem is that it seems to transmit the
characers to the port, but doen't recieve any?  Also it seems to
transmit it to both com1: and com2: even though I don't have the
modem card installed.  Mind my program works ok with the modem card
at 300 BAUD but I would like 1200 BAUD.  In reading the IBM Jr. Tech
refernce it is set up differently then the PC's but I must be missing
something some where.

thanks

Bradley Smith			UUCP: {cepu,ihnp4,noao,uiucdcs}!bradley!brad
Text Processing			ARPA: cepu!bradley!brad@UCLA-LOCUS
Bradley University		PH: (309) 676-7611 Ext. 446
Peoria, IL 61625

Message-ID: <20386@arizona.UUCP>
Date: Mon, 21-Jan-85 15:30:40 EST
Article-I.D.: arizona.20386
Posted: Mon Jan 21 15:30:40 1985
Date-Received: Tue, 22-Jan-85 06:18:05 EST
References: <900009@bradley.UUCP>
Organization: Dept of CS, U of Arizona, Tucson
Lines: 35


i also am working on getting a terminal emulator to work on the JR.  There
are several problems.  The first problem it looks like you've encountered
is that all of the system software migrates, depending on whether you've
installed the internal modem or not.  Without the modem, the serial port
is COM1.  With the modem, the serial port is COM2 and the modem is COM1.
... a little brain-damaged!

Other problems that you'll soon encounter are that race conditions in the
Jr. are even more serious than in the other PC's.  The technical reference
suggests "NO BACK-TO-BACK" 8250 instructions.  Also, it suggests that if
your program will be expected to handle keyboard and modem interrupts, then
don't even try using baud rates above 1200.

Finally, there is no dma in the Jr. so disk operations go much more slowly.
And worse, while the disk operations are taking place, ALL OTHER INTERRUPTS
ARE DISABLED.  Most of the file transfer protocols are designed such that
this is not a problem as long as the programmer is careful about when s/he
sends an acknowledge.  However, lots of programmers get a little sloppy when
writing for the PC, which handles disk i/o much more intelligently.

Other things to look out for are that video memory is not mapped the same
as in the PC.  This makes it difficult to get lots of terminal emulators
to run properly.

I was quite surprised to discover all of these problems, considering that
earlier someone had posted such a strong endorsement of the Jr. in comparison
to the Sanyo MBC 550.  I've had some experience with both, and my opinion
is that neither is compatible enough with the bigger family to take programs
off the shelf for the PC and expect them to run.  And I believe the 
Sanyo is more open-ended (two disk drives, up to 256K memory without expensive
add ons).  However, the PC Jr. will probably have the greater abundance of
software suppliers.

kelvin nilsen - author of VersaCom for the IBM PC