By Todd R Lynch

IN JANUARY 1980, Hewlett-Packard made its first entry into the personal computer marketplace with a product called the HP-05 (Fig. 1), a totally self-contained computer system for the technical professional or first system for the beginning small-computer user. It is based on a custom eight-bit microprocessor, with an operating system and BASIC* language commands stored in 12K bytes of ROM (read-only memory). There are 16K bytes of RAM (random-access memory) in the machine, with the capability...

Horizontal Amplifier

In the design of the horizontal amplifier I Fig, 4). most ol Ihe circuitry is conventional. However, in the interest of power conservation, and because a 127-mm CRT must have very small border margins, a phase control loop was added. Its function is to assure beam position with respect to dot timing. With this design, the overs canning normally required to compensate for phase errors becomes unnecessary, and drKe i urrent is reduced. The circuit uses a conventional 555 timer that Iriggers on...

Interface Select Codes and Device Specifiers

The HP-85 can have up to three interface cards plugged into it see Fig. 5 . It also has the internal CRT and printer that I O ROM users may want to access. How does a programmer tell the I O ROM which of these devices to interface with This is done through interface select codes. Every I O ROM statement that deals with an interface specifies as part of the statement the interface select code. The range of select codes is as follows t INTERNAL CRT 2 INTERNAL PRINTER t EXTERNAL I O Select codes 1...

An Efficient Power Supply for the HP

As wth tie rest ot ihe HP-85 system, the efficiency of the power supply must be high. Also, the regulation at tow frequencies is important since annoying CRT display modulation results if trace amounts of ac line ripple are present Switching spikes can also cause ripples in the display The solution to these problems is a switching supply synchron ,7ed to twice trie scan frequency of the CRT Fig. 1 . The heart of this supply is a pulse-width modulator IC that is synchronized by a 32-kHz twice...

By Douglas J Collins and Brian G Spreadbury

OVER THE LAST FOUR YEARS Hewlett-Packard has developed a series of magnetic transports1, for the 9820UA data cartridge shown in Fig. 1. The use of this small data cartridge was selected because of proven reliability, large data capacity, ease of use, and low system cost. The tape system integral to the 11P-85 is in many ways a refinement of prev ious designs. However, the total integration of the transport with a single printed circuit hoard into one small package called for new techniques in...

By Clement C Lo and Ronald W Keil

BUILT INTO THE HP-85 Personal Computer is a moving-head, thermal printer .'plotter, This unit is a compact. medium-speed, smart peripheral that quietly outputs program listings or hard copies of the alphanumeric and graphics data displayed on the CRT. The printer is designed to print two lines per second for alphanumeric copy. Each line can have up to 32 characters. For graphics copy, the plot displayed on the CRT is rotated 90 before it is printed. This provides the capability for forming...

By James F Bausch

ONE OF THE TWO PRIMARY output peripherals integrated into the HP-85 Personal Computer is a high-quality CKT display. The other, a thermal printer, is described elsewhere in ibis issue. In addition to design goals of display quality and small size, ihe HP-85 CRT subassembly was to have low power consumption. The 127-mm diagonal, black-and-white, electromagnetic-deflection CRT can display information in the form of lines of alphanumeric characters or provide a plotting area for graphics output....

By John H Nairn Tim I Mikkelsen and David J Sweetser

THE HP-85 is tin integrated, stand-alone personal computer. This means that within this single package are contained all of the elements of a small computer system. Part of Fig. 1 shows a block diagram of the HP-85 mainframe. The box labeled CPU contains the main processor, ROM and RAM memory, operating system. power supply, and all of the other elements that in a large mainframe or minicomputer would constitute the computer itself. The remaining elements provide the human interface, letting a...

By Nelson A Mills Homer C Russell and Kent R Henscheid

HP-85 BASIC is an enhanced implementation of the American National Standard for Minimal BASIC ANSI X3.60-1978 . It is designed to provide the user with a friendly, easy-to-use. and powerful programming tool. The BASIC language interpreter and the HP-85 operating system are implemented entirely in firmware to relieve the user of any responsibility for getting the operating system and or interpreter loaded and executing. For the novice user, the HP-85 features an autoslarf mode of operation. When...