This Web page is constructed from notes from the Tiny BASIC manual for the BASYS card. BASYS is an 1802-based card designed by Lee Hart in 1982. This note Last updated Feb 16 2012. Edited by Herb Johnson, (c) Herb Johnson
CHAPTER 3
HARDWARE REQUIREMENTS
TMSI Tiny BASIC will run in the BASYS/1 microcomputer, or any other
COSMAC based system that meets the following minimum requirements:
CPU RCA, Hughes, or Solid State Scientific "COSMAC"
microprocessor; 1802, 1804, 1805, or 1806. Any clock
frequency is acceptable; however, it sets the maximum baud
rate for serial communications (see I/O below).
MEMORY RAM: 256 bytes minimum, fully decoded and starting at
address 1000 (hex). TMSI Tiny BASIC will test for RAM
starting at this address, and adapt itself to the amount
found. RAM in excess of 256 bytes is used to hold Tiny
BASIC programs, so the more RAM, the larger the program.
BASIC ROM: One socket for a 27C32 4K byte EPROM, fully
decoded at address 0000. EPROM access time is 450nS,
which is acceptable for COSMAC systems running at up to
5 MHz. Data in the EPROM is active high (not inverted).
Execution should begin at 0000 with P = X = 0.
User EPROM (containing user BASIC programs): 1K bytes
of space are available in the TMSI Tiny BASIC EPROM for
user BASIC programs. Additional EPROMs may be added for
larger programs. They must be addressed above the first
page of RAM at 1000 (hex), and preferably above all RAM.
If a user EPROM is found by TMSI Tiny BASIC after reset,
it will be executed immediately as a BASIC program. If a
user EPROM is not used or not addressed immediately
above RAM, then pull-up resistors to +5v should be used
on the data bus to insure that TMSI Tiny BASIC does not
mistake a floating data bus for a user EPROM program.
I/O User terminal input and output is serial ASCII, using the
COSMAC's EF4 and Q pins respectively with a "software UART"
program. The baud rate can be from 60 to 2400 baud with a 2
MHz clock; scale proportionately for other CPU clock
frequencies. TMSI Tiny BASIC automatically determines the
baud rate from the first character received after Reset,
which should be a (your RETURN or ENTER key) for full
duplex, or (your LINE FEED or control-J key) for half
duplex. See Appendix A for a sample RS-232 serial interface
circuit.
CHAPTER 4
INSTALLATION
These instructions are for the TMSI BASYS/1 microcomputer. However,
they should serve as a guide for other systems as well. To avoid
damaging the parts from static electricity, follow the instructions
exactly as given. Then place a check mark in the space provided ( ).
( ) Touch the metal case of crystal Y1 on the BASYS/1 board first to
discharge any static potential safely.
( ) U11: Remove the chip at U11 from its socket, and hold it in one
hand. With the other hand, pick up the piece of protective foam
holding the Tiny BASIC IC. Insert U11 into the back of this
piece. Now remove the Tiny BASIC IC, and insert it into socket
U11. Be sure to position pin 1 (with the dot) as shown below.
( ) X5: Install jumpers at ____________________________________
pins 1-2, 3-14, 6-12, / | | \
and 8-10 (configures | | P2 | |
U11 for a 27C32 EPROM). | |::::::::::::::::::::| |
.-----------------. | `--------------------' |
| O O O O O O O O | | .-----. .----. .--------. .--..--. |
| | | | | | |.U3 | |.U9 | |.U17 | U25|U26| |
X5 > _ | \ \ | | `-----' `----' `--------' `--'`--' |
| | | | | | | | .-----. .-----. .--------. .-----. |
| O O O O O O O O | | |.U2 | |.U8 | |.U16 | |.U24 | |
`-----------------' | `-----' `-----' `--------' `-----' |
( ) XD2: Install five diode | .----------------. .------. .-----. |
jumpers as shown (A= | | | |.U15 | |.U23 | |
anode, C=cathode). Puts | | BREADBOARD | `------' `-----' |
RAM at 1000-17FF (hex). | | AREA | .------. .-----. |
.-------------------. | | | |.U14 | |.U22 | |
| O O O O O O O O O | | | | `------' `-----' |
| | | \ \ \ | | `----------------'.------. .---. |
XD2 \ C A C A C | | .------. .----. |.U13 | |.X6| |
/ A C A C A | | |.XD2 | |.X3 | `------' `---' |
| \ | | | | | | `------' `----' .------. .-----. |
| O O O O O O O O O | | .------. .-----. |.U12 | |.X5 | |
`-------------------' | |.XD1 | |.U7 | `------' `-----' |
( ) XD1: Install four diode | ------ ----- .---------. |
jumpers as shown. Puts | .-----. .------. | | .-----. |
BASIC at 0-0FFF (hex). | |.U1 | |.U6 | | | |.U21 | |
.-------------------. | `-----' `------' |.U11 | `-----' |
| O O O O O O O O O | | `---------' |
| \ \ \ \ | | .------------------. .----. |
XD1 \ A C A C | | | | | | |.U20| |
/ C A C A | | .----. | | `----' |
| | | | | | | | | |.U5 |D20 |
| O O O O O O O O O | | | Y1 | `------------------' .-----. |
`-------------------' | | |.-----. .-----. .-----.|.U19 | |
( ) D20: If diode D20 is | `----'|.U4 | |.U10 | |.U18 |`-----' |
installed, remove it. |__ `-----' `-----' `-----' __|
| P1 |
This completes installation | |||||||||||||||||||||||||||||| |
of the TMSI Tiny BASIC EPROM. |_||||||||||||||||||||||||||||||_|
Components used on BASYS as per layout above. May be in error. - HRJ U1 - 4069 inverter IC U2 - 4020 counter U3 - 74LS145 decoder U4 - 22K SIP common to +5 U5 - 1802 or similar U6, U7 - 4042 latch U8 - 330 DIP resistor pack U9 - 4.7K SIP resistor pack U10 - 22K SIP resistor package, common to +5 U11 - ROM ex. 2716 U12, U13, U14, U15 - 2114 RAM U16, U17 - 74LS373 U18 - 22K SIP resistor pagkage U19 - 4556 decoder U20, U24 - 4013 Flipflops U21, U23 - 4011 NAND U22 - 4001 AND U25 - 4N30 opto isolator U26 - 4N28 opto isolator XD1, XD2 - diode array on DIP header X3, X5, X6 - jumpers on DIP headers Y1 - crystal
APPENDIX A
SERIAL TERMINAL INTERFACE
The following circuit or its equivalent will provide a COSMAC
microprocessor with a minimal RS-232 serial interface suitable for
TMSI Tiny BASIC. It is capable of operating up to 9600 baud.
+5v
|
|
22K > 25-pin RS-232
Resistor > "D" Connector
____________ > 2N4401 NPN 3.3K
| ___ | | Transistor Resistor
| EF4 |_21______|______C E__________/\/\/\________TXD
| | _\___/_ | pin 2
| | |B _|_
| | | _\_/_ 1N914
| | | | Diode
| | _|_ _|_ ____RTS
| | = = | pin 4
| | Ground |
| | |____CTS
| | pin 5
| | +5v
| | |
| | |
| | > (note 1) ____DSR
| | 22K > +5 to +15v | pin 6
| | Resistor > | |
| | | | |____DTR
| | | > pin 20
| | | /E > 1.8K
| Q |_4______|/ 2N4403 PNP > Resistor
| | B|\ Transistor |
| | | \C |_________________RXD
|____________| | | /C pin 3
|____________|/ 2N4401 NPN
COSMAC | B |\ Transistor
Microprocessor | | \E
> | _______COMMON
> 22K | _|_ pin 7
> Resistor | =
| | Ground
|_______________|
|
|
-5 to -15v
(note 1)
Notes:
1. Equal and opposite power supply voltages for RS-232 interface.
2. RTS-CTS and DSR-DTR jumpers may be required by some terminals.
This page and edited content is copyright Herb Johnson (c) 2012. Contact Herb at www.retrotechnology.com, an email address is available on that page..