Browse Prior Art Database

Simple PC Printer Port FPROM Programmer

IP.com Disclosure Number: IPCOM000100161D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Gorga, KJ: AUTHOR

Abstract

Flash Programmable Read-Only Memory (FPROM) is a new form of memory which is electrically programmable and electrically erasable. This allows for very fast code updates because the part can be erased and reprogrammed in a few minutes rather than an hour like ultraviolet erasable EPROMs. A simple and inexpensive programmer is needed to program the parts.

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This is the abbreviated version, containing approximately 52% of the total text.

Simple PC Printer Port FPROM Programmer

       Flash Programmable Read-Only Memory (FPROM) is a new form
of memory which is electrically programmable and electrically
erasable.  This allows for very fast code updates because the part
can be erased and reprogrammed in a few minutes rather than an hour
like ultraviolet erasable EPROMs. A simple and inexpensive programmer
is needed to program the parts.

      The programmer consists of only five ICs and can attach to a
modified PC Printer Port or an unmodified PS/2* Printer Port.  A
small program allows listing, erasing, verifying and programming the
part.

      The schematic diagram of the PC Port FPROM Programmer is shown
in the figure.  The A and B port of the 8255 (U1) is used as
an Address latch for the FPROM (U2).  The C port is used as a
data-out latch for the FPROM.  U3 and U4 serve as a data bus
transceiver for the FPROM.  U6 is a small switching power supply IC
used to develop the 12.75 volts to program the FPROM from a standard
5-volt logic supply.

      To program the part, the Address is loaded into ports A and B
of U1 and the data byte is loaded into port C.  Bit PB7 of port
B is used as the Write Enable line for the FPROM. Data buffer U4 is
enabled whenever a Read is not taking place.  This presents the data
byte to be programmed from port C of U1 to the FPROM.  To read the
FPROM, the address is applied to ports A and B of U1 and a read
is done.  A read will disable U4 (the port C buffer) and enable U3
(the FPROM data buffer) placing the FPROM Data on the Printer Port
bus.

      The Printer Port is used for parallel data transfers to the
programmer.  The...