HP Portable Plus (45711): Part 1
18The Portable Plus was a "simple" MS-DOS compatible machine running on an 80C86. By simple I mean there is no in-built floppy drive and various ports ... there's just a DE9 RS232 serial port and a HP-IL interface (Hewlett Packard Interface Loop) for connecting peripherals. Oh, you could also get an internal modem. Nice and simple.
My example is the 45711B ... the "B" indicates 128KB RAM and no modem:
45711A ... 128KB, modem
45711B ... 128KB, no modem
45711C ... 256KB, modem
45711D ... 256KB, no modem
45711E ... 512KB, modem
45711F ... 512KB, no modem
An additional letter indicates the language/keyboard, for example 45711FF indicates French. No additional letter means the US version. More information from the documentation here:
http://www.hpmuseum.net/exhibit.php?hwdoc=49
{The service manual is pretty good}
There are some expansion options - I have an additional 128KB of RAM in a "memory drawer":
82981A ... 128KB expansion RAM
82992A ... 1MB expansion RAM
82982A ... Software Drawer for ROMs
82984A ... some sort of expansion with 128KB ... not sure
82985A ... video interface
The machine comes with 192KB of ROM.
I need to repair some cracks from shipping, but otherwise the machine looks pretty solid & simple.
I am wondering whether I can upgrade the base system RAM board, the 82981A expansion RAM board, or build something for the spare/empty expansion drawer ... ?
Additionally, I guess I need to source a new internal battery (Panasonic LCR-226P, obsolete but I believe alternatives are available) and a 12VAC plugpack to power/recharge the machine.
I also need to finish building the USB-to-HPIL interface I have so I can transfer software:
http://www.jeffcalc.hp41.eu/hpil/