One of the early Microsoft 6502 Basic versions, made for the SYM-1.
Two versions were made. The first came as two 4K ROMS, V1.1 as one 8K ROM. ROM ID BAS 023-0025A.
The tri-goniometric functions, an option at startup are documented in the Basic manual as hex dump or on page 27 in the Technotes
There were two versions of the BASIC ROMs available.

• A two ROM set (part numbers 02-0019-01 and 02-0020-1). These went into sockets U21 and U22 respectively.
• A single ROM (part number 02-0058 A/B). This went into socket U21. It’s 8K and it’s position dependent. It fits in from $C000 to $DFFF.

The 8k Basic has tokens but no code for the trig functions. There’s an application note which invites you to type in the hex and save to tape the approx 512 extra bytes needed. See page 27 of the tech notes.

The 1981 manual shows the correct jumpers for an 8K ROM in U21. The 1978 manual shows the correct jumpers for two 4K ROMs in U21 and U22

BASIC Manual second printing.

ROM binaries

• Basic v.1.0 first ROM at C000
• Basic v.1.0 second ROM at D000
• Basic V1.1 8K ROM at C000
• TRIG object code dump form Basic and TEchnotes
• Ascii dumps of V1.1 and information by Leland Goertz
• Loadable extended SYM-1 BASIC by John JOHN W. Brown 1980 SATURN SOFTWARE: TRACE, TIME etc ($0200-11FF)
• Loadable SYM-1 Basic extensions (tape?) ($1200-1705)
• Disassembly by Lee Davison of V1.1

BXT_1200 is just 1285 useful bytes, and then filled with FF. It contains the strings PERFECT MATCH!, COMPARE ERROR AT, CHECK SUM ERROR! and INVALID DELETE RANGE!

BXT_0200 is a full 4k bytes, and contains these strings:
FOUND LOADING SEARCHING FOR SAVING CALL STIME EDIT PAGE TRACE CHAIN EXEC PAGE EXTENDED SYM-BASIC BY JOHN W. BROWN COPYRIGHT (C) 1980 SATURN SOFTWARE LIMITED

SYM-1 monitor

The SYM-1 monitor, Supermon, is described in the Reference manual
Written by Manny Lomas, of TIM and RAP fame.

Two versions of the monitor were shipped, Version 1.0 and Version 1.1.
Version SY1.1, the second release of Supermon, is described in a separate manual.

Appendix M describing the version 1.1 Monitor enhancements and listing.

• ROM of SY1.0, 4K start address 8000 (ROM ID 0100012)
• ROM of SY1.1
• Assembler Source listing

The ROM contains Supermon, the machine monitor, the audio cassette functions and the boot ROM function (vectors and such are cleverly loaded into RAM by some hardware tricks with protected RAM at upper memory.

A DOS for the SYM-1, based upon the Commodore 1541 System

See also

• Galactic Expansion Board

The DOS was sold by Ronald A. Jordan in 1984, who sold this DOS thru his company, Jordan & Associates. This 1541 DOS system was sold as object code on a cassette tape. For an additional fee he would burn an EPROM as well as provide the object code on cassette tape and for still another an additional fee, he would provide the source code on cassette tape.
The 1541 physical interface was also provided by Jordan and consisted of a very simple box with one 7416 hex inverter chip with the mating connectors for the SYM and Commodore 1541 Disk Drive.
The Commodore 1541 disk drive was affordable, around $300 in 1983. A logical choice at the time therefore, since the serial IEC bus is so easy to operate on a small 6502 SBC and the whole DOS included in the drive itself, avoiding a DOS for the SBC. Disadvantages of course are the slow IEC bus and nowadays the vintage character of the 1541 drive. Since there are alternative ‘1541 compatible drives made by hobbyist, with an SD as storage it is still interesting to add this to a SBC (SD2IEC, Pi1541 etc).

On this page all available information is collected about this 1541 DOS.

The information on the 1541 DOS is from these websites:

• Dallas Shell page on DOS for SYM-1
• Radiotools page on SYM-1
• SYM-1 Expansion Board Documentation – Galactic Studios

Added by me are the sources of the 1541 DOS, the scanned version was lost long ago on teh page of Dallas.. But I did keep a copy. In 2006 the source has been typed in by me in normal 6502 assembly.

The 1541 DOS package consists of a manual, a tape with 1541 DOS code and optionally a hardware interface tot the IEC of the Commodore 1541 and also optional source code on tape.

The 1541 DOS code is made up of interfacing code for the IEC bus, and integration for the Monitor, Basic and RAE. The fuctcionality is limited to showing directories, loading and saving memory, but no data file support. It ix possible to give to the 1541 drive ‘special’ commands, e.g. format a drive. More than one drive is supported.

Hardware

The interface is simple, just an open collector TTL IC, 7416, 3 inputs and 3 outputs of the VIA 6522 to the IEC serial bus ATN, DATA and CLOCK and RESET

See also:

• Galactic Expansion Board

Software

Part is interface to the IEC bus (bit banging), the other parts are linking to Monitor, RAE and Basic.
Functionality offered:

Downloads

	Original 1541 DOS documentation (cleaned up, complete) 1. SYM 1541 DOS Manual 2. Hardware interface circuit Design 3. Source of 1541 DOS, RAE Basic Monitor driver 4. Crossreference of software 5. Contents of Utility Disk
Cheat-Sheet.pdf	DOS 1541 short userguide for SYM-1, Monitor, RAE, Basic
1541DOS_OBJ_PTAPE.TXT	DOS 1541 code for address $7000 (see notes below)
1541DOS 9000.txt	DOS 1541 code for address $9000 (see notes below)
1541dos.bin	1541 DOS binary for address $9000
sym1541.asm	1541 DOS in TASM format (typed in from listing, not tested yet!)
1541DOS_RAE.txt	1541 DOS in RAE format

Note

The object code assembled to run at $7000 is in SYM paper tape format. Note this code is assembled to run at $7000 but will load into $1000 from the paper tape load. The object code assembled at $9000 is also in SYM paper tape format. Same rules apply for loading etc.