MEMORY PLUS Manual By Lee Davison and Hans Otten Back to The Computerist
EPROM Programming The usefulness of the EPROMs on the MEMORY PLUS board is enhanced by the inclusion of on board EPROM programming facilities. The INTEL 2716 EPROM is electrically programmable and ultraviolet light erasable. The user can buy or build an ultraviolet light eraser. MEMORY PLUS provides the parts required for the programming of the EPROMs. These parts consist of the following items: EPROM Programming Socket: Socket 79 is a 24 pin socket located toward the lower right hand corner of the board. The EPROM to be programmed is placed in this socket. +25 Volt Regulator: +25 volts is required for programming the 2716. This may be provided directly by the user at pin A-22 of the MEMORY PLUS application connector. Since this voltage is so critical, and since an over voltage can destroy an EPROM, an on board regulator circuit is provided. This will provide about 24.7 volts when supplied with +27 to +30 volts at pin E-3 of the MEMORY PLUS expansion connector. Control Lines: The EPROM requires eleven (11) address lines, eight (8) data lines, and two (2) control lines. All but three of these lines are provided by the MEMORY PLUS VIA 6522. The remaining three lines come from the MICRO port B: PBO, PB1, and PB2. Timing: EPROM programming requires a 50 millisecond pulse be applied to the EPROM. The VIA 6522 includes a timer which is used for timing this interval. EPROM Programming Program: The control of the programming is handled by a program run on the MICRO. This program is provided in the form of a source listing in this manual and as a cassette tape included in the MEMORY PLUS package. The 2716 EPROM may be programmed one location (byte) at a time, or the entire EPROM may be programmed. The steps required to program the EPROM are: 1. With the power off, insert the EPROM to be programmed into the Programming Socket. 2. Turn on the power and load the data to be copied into the EPROM into any portion of memory. This may be RAM memory loaded from cassette (or by hand) or may be another EPROM which is going to be copied. 3. Load the EPROM Programming Program from cassette (or by hand) into memory (locations 0000 to 00D8) 4. Make sure the following application connector connections are in place: MICRO A-9 TO MP A-19; MICRO A-10 TO MP A-20; MICRO A-l1 TO MP A-21