HP 9825A - Introduction The HP 9825A is one of the second generation desk top calculators. It was introduced in the June 1976 issue of the HP Journal as a follower of HP 9820 and 9821 models. While in year 1976, Intel produced 4040 and 8008 microprocessors, Hewlett Packard used for the HP 9825 a multi-chip hybrid module with three NMOS chips and four chips for drivers. The HP 9825 had standard R/W memory of 6844 bytes, with option up to 32 kBytes The calculator had two-level priority interrupt, a live full "QWERTY" layout keyboard, a built-in 16 column thermal printer, a magnetic cartridge tape drive, a built-in 32 column LED dot matrix alphanumeric display. It had also four optional ROM slots in the front and three I/O interface slots in the rear of calculator. The live keyboard feature allowed changing variables or program statements while the program is running, or to list the program while it is running. The keyboard was available in several language options and includes a numeric keyboard with dedicated keys for the four basic math functions and parenthesis keys. The display had 32 LED dot-matrix 5x7 characters, but up to 80 characters could be input at a time. After the 67th character was input, the machine would beep to indicate that it was nearly full. In the contrary to it's predecessor, the HP 9825 had new tape driver which replaced the Philips tape-cassette drive used in HP 9830 and HP 9821. The new tape driver used the 3M DC-100 tapes and had higher capacity (250 kB) and was faster and more reliable. The 16 charactes thermal printer was the same as used in HP 9815. The 9825A operated in full algebraic mode, meaning that problems are typed into the machine as pretty much as they would be written on paper. It was also programmable in High Programming Language, called HPL, compatible with HPL used by the HP 9820 and 9821. HPL was HP's version in that time widely popular APL language. HPL allowed subroutine nesting, flags and multi-dimensional arrays of up to the size of the system memory. The optional ROMs allowed strings, I/O operations, supported plotter, HP-IB and much more. The 9825' HPL was compatible with HPL used by HP 9816 and HP 9836A and later with HPL used for the 9000-200 series computers. The HP 9825 models were replaced in 1983 with HP 9826 known as "AKA 9000-226". The price of HP 9825A in 1977 was US$ 5,900.