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Hewlett Packard 82104A Magnetic Card Reader/Writer

• Type: Optional Calculator Accessory
• Size: 3 x 3 inches / 8 x 8 cm
• Serial number: 2020S45726
• Date of Manufacture: May 1980

Plugs into an expansion ROM slot and is held in place by two clips that fit into the top end of the calculator case. Stored about 32 registers of memory, 224 bytes, on each card (using two tracks on the card). This would also store a program of about 200 instructions (instructions are variable in size, so YMMV.)

Functions:

• MRG Merge program from card
• RDTA Read data card
• RDTAX Read data card per X register
• RSUB read subroutine
• VER Verify track
• WALL Write all
• WDTA Write data
• WDTAX Write data per X register
• WPRV Write private program
• WSTS Write status

The card reader will also read cards written with the HP 67 and HP 97. Certain functions of those calculators are sufficiently incompatible that the card reader supplies a number of compatibility routines to be used in translation.

• 7CLREG HP 67/97 Clear registers
• 7DSP0 HP 67/97 Display digit 0
• 7DSP1 HP 67/97 Display digit 1
• 7DSP2 HP 67/97 Display digit 2
• 7DSP3 HP 67/97 Display digit 3
• 7DSP4 HP 67/97 Display digit 4
• 7DSP5 HP 67/97 Display digit 5
• 7DSP6 HP 67/97 Display digit 6
• 7DSP7 HP 67/97 Display digit 7
• 7DSP8 HP 67/97 Display digit 8
• 7DSP9 HP 67/97 Display digit 9
• 7DSPI HP 67/97 Display indirect
• 7DSZ HP 67/97 Decrement and skip on zero
• 7DSZI HP 67/97 Decrement and skip on zero indirect
• 7ENG HP 67/97 Engineering notation
• 7FIX HP 67/97 Fixed notation
• 7GSBI HP 67/97 Gosub indirect
• 7GTOI HP 67/97 Goto indirect
• 7ISZ HP 67/97 Increment and skip on zero
• 7ISZI HP 67/97 Increment and skip on zero indirect
• 7P<>S HP 67/97 Exchange primary and secondary registers
• 7PRREG HP 67/97 Print registers
• 7PRSTK HP 67/97 Print stack
• 7PRTX HP 67/97 Print X register
• 7RCLΣ HP 67/97 Recall statistics registers
• 7SCI HP 67/97 Scientific notation