Similar in appearance to the IBM 5100 from five years earlier in 1975,
the Hewlett-Packard HP-85 is an all-in-one portable computer system with a built-in keyboard, 5″ screen,
thermal printer, tape storage unit, and the BASIC programming language.
With its top off, it can be seen that the HP-85 has a clean and simple layout.
On the left is the monitor and display circuitry, on the right is the thermal printer and
tape storage mechanism.
The main motherboard is beneath the keyboard, shown here folded up. Except for the eight memory chips,
all of the chips are custom HP designed.
There are four ports on the back for expansion carts.
The HP-85 has a custom Central Processor (CPU) from Hewlett-Packard which runs at a slow 613KHz. Why? HP says:
Why does HP use its own custom CPU? One of the most important reasons is ACCURACY.
Where other computers do binary arithmetic, the HP-85 does its arithmetic in BCD (binary coded decimal).
Our calculators do BCD arithmetic, and we’ve spent years testing and perfecting those algorithms, so we KNOW
that the answers returned by the HP-85 are accurate to 12 digits. Real number calculations in the hp-85 are performed
internally to 15 significant decimal digits and rounded to 12 digits for presentation.
There are a couple of ways to build a CPU – make it simple and run it fast, or make it complex and run it slow.
But, execution speed is more than just a function of hardware design, and the HP-85 executes programs on the same order
But all of this is another story. The point is that the HP-85 is a machine that is inherently accurate, fast, and affordable.
But really, incompatible software is a short-term problem. Most forthcoming software will necessarily have to written in
Released in 1982, the low-profile HP-86 personal computer offered users more options and expandability than the HP-85, which had been introduced two years
earlier. It has no internal display, printer, or data storage – all of these are now external peripherals.
The HP-86 came standard with 48K of RAM.
In 1982, Hewlett-Packard released the HP-87 computer, as seen here to the right.
It sacrificed the built-in printer and tape backup for the extra-wide video screen.
The HP-87 is capable of displaying 80 columns X 16 rows of text, as well as 400 X 240-dot graphics,
on a unique high resolution
The HP-87 has 32K internal RAM – four times that of the HP-85. The HP-87XM has a whopping 128K RAM.
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