SAVE1500 VERSION 1.01
        Transfer .P files from PC to a TS1500 or ZX81
                 through the parallel port
       (c) 1999 Luis C. Grosso -- ets@citynet.net.ar


                   
This program is machine coded, of course.

This version includes:

SAVE1501.COM - Executable file
SAVE1501.ASM - English commented Source file
SAVE1501.TXT - This file

SYSTEM REQUERIMENTS
Any PC AT compatible computer from 386SX-33 thru 486DX4-100.
One parallel port at 03BCH, 0378H or 0278H
It was not tested on faster and slower computers.

It uses machine independent time delays taking advantage of
the i8253 programmable interval timer.

CABLE CONSTRUCTION
Materials :                             QTY :

DB25 male connector                     1
3.5 mm mini plug (suitable for zx81)    1
shielded cable                          4 or 5 feet
resistor 470 ohm                        1

Connect pin 24 (GND) to the cable shield, and the other end to the ring
terminal of mini plug.
Connect a 470 ohm resistor to DB25 pin 2 (D0) in series with the live wire,
and the other end to the tip terminal of mini plug.

                               470 ohm   __________
                            +-/\/\/\________________ tip
    DB25 male rear view    2|            __________
    ____________________________         |       ring
13  \ . . . . . . . . . . . . . / 1      |
 25  \ . . . . . . . . . . . . / 14      |
       -----------------------           |
         |24                             |
         +-------------------------------+

A 470 ohm resistor is used to protect the parallel port TTL output against
accidental short circuits especially when inserting and removing the plug
from the zx81 socket.


Parameters are passed through the command tail.

Usage : SAVE1500 1|2|3 filename[.P]

Where : 1 -> 03BCH  \
        2 -> 0378H   |> the parallel port base address.
        3 -> 0278H  /

If no extension is given in the filename then .P is assumed by default.
Data transmission may be aborted at any time by pressing SPACE.
Now it can be also aborted during the initial pause.

This program is freeware, feel free to distribute it Without any Modification.
But any donations will be welcome, i.e. u$s 5.

Beg your pardon for my poor English.

                                        Luis C. Grosso
                                        Callao 3869  2000 Rosario
                                        Argentina