Micro­power

programming pulse of 50 milliseconds per address. It takes about 2 minutes to program either type.

While the programming is going on, a display is put on the screen to show that something is happening. With 2708s the number of programming cycles left is displayed (in hexadecimal). With 2K EPROMS a count is output every 100H (256 decimal), beginning with 00 at the beginning of the first block.

Note that ths software is written for a 4 Mhz clock and NO WAIT STATES. If either are changed, then the value 0E0H in the B register (for the 2708 routine), or 1D00H in BC (2516/2716 routine) will have to be changed. Short delays are written into the software to allow time for line stabilisation or chip ‘set-up’.

C – Compare Contents Of EPROM With RAM

This routine will compare the EPROM and RAM, byte by byte. It may be used to check for correct programming, or to find small discrepancies between EPROMs and RAM that should be identical. If a mismatch is found the address of the byte in RAM that did not correspond with the ‘EPROM’ will be printed on the screen, and a message that the data did not match will be printed at the end of the routine. If the EPROM and RAM match the routine will end with a suitable message.

T – Transfer Data From Eprom To Ram

This routine will quickly copy the contents of the chip into RAM, starting at the RAM address entered. This data may then be disassembled, modified, relocated, or used to make a back-up copy as desired. On completion of the routine a message is displayed, as there is no other indication that the routine has run its course.

D – Dump To Printer

This routine was written with the ‘ IMP’ printer in mind, and so it interfaces through the serial port. A handshake routine is included (using bit 7 of the keyboard port), to avoid having to set up user routines. The program starts by requesting the normal address of the EPROM. It prints this address, followed by sixteen bytes of data and the ASCII characters corresponding to this data (for characters 20H to 7BH; all other characters are printed as ‘.’). A new line is started, and the address is updated, and the routine is continued until all the data in the EPROM has been printed out.

The routine works by reading sixteen bytes from the chip into a workspace buffer (label LINBUF in the source code, pointed to by the IY register). These bytes are then printed, another sixteen bytes read in, and so on.