Unc

Custodian of the Sam Coupé Scrapbook first arrived under the guise of ‘Tizo’ with StarShot on Fred 24.

Produced EGGBuM as Sad Snail Productions.

MGT

SamDOS 1.1 was the original DOS for the Sam Drive and external drives via the External Drive Interface.

Version 1.1 source of many problems highlighted in one of the most corking ROM bugs in ROM 1.0 that prevented correct bootstapping forcing the user to enter a CALL command (CALL 229385 for 256K or on a 512K CALL 491529) after pressing F9 or typing BOOT.

SamDOS 2.0 was released along with ROM 2.0 and booted correctly, although this episode forced MGT to ship new ROMs to all customers.

Information from Frode Tennebø from the Sam Coupé Scrapbook

Introduction

SAMDOS has been designed specifically for the SAM Coupe computer. It is similar to G+DOS as used with the MGT Plus D Spectrum disk interface.

Disk Format

We use 80 track per side, giving 160 tracks per disk. A track is made up of 10 data sectors, each giving 512 bytes of storage.

The first 4 tracks of the disk are given up to the SAMDOS directory, leaving 156 tracks available for storage. This leaves available 1560 data sectors of 512 bytes (798720 bytes).

Although each data sector can hold 512 bytes, only 510 bytes of them are available for storage. The last two bytes of the data sector are used by the DOS to locate the next part of the file stored. Byte 511 hold the next track used by the file, while byte 512 holds the next sector.

BetaSoft

Dr Andy Wright

In the same way that MasterBasic was Dr Wrights improvement to Sam Basic, MasterDOS was the improvement to the original SamDOS.

MasterDOS contains many features missing from the original, such as file directorys, date and time stamps using the real-time clock in the SamBus or in the Dallas Clock from Edwin Blink.

Another feature that was highly prized was the ability to set up Ram Discs which was especially useful with the One Meg extension that could be formattted into a complete 800k virtual disc.

See also MasterDOS Hook Codes

PDF Manual Scan at www.samcoupe-pro-dos.co.uk

Review by Tim Paveley from the Sam Coupé Scrapbook

Urm, I got SamDOS free with my Sam, why do I need another one?

Because it’s just packed full of useful new features, that are of use to even a total beginner. I’ll tell you the 3 most useful features it has.

1. The most useful thing is that you can now have subdirectories, which makes file management far more easier. Each Subdirectory uses a free directory slot, but that’s it. They are incredibly useful, since they allow you to ie store all your word processing files in one directory, and all your pictures in another. Subdirectories can contain furthur subdirectories, and so on, allowinf nice tree like structures of files.
   
2. Another useful thing, is that it allows you to set aside areas of memory to use as a RAMDisk. This Basically acts as another (faster) disk drive, that you can carry out normal operations on. If you have a load of files to copy, copying them all to a RAMDisk, and then to the target disk, is a lot easier than 20 or 30 disk swaps. The RAMDisk is limited by the amount of free memory you have, and can be as large as a normal disk (800k), very useful if you have a 1meg expansion!
   
3. The 3rd “useful for anyone” feature, is that you can now reserve extra tracks on the disk for directory information. Basically this means that you can have more than 80 files on a disk, upto a maximum of 778, useful if you have a lot of small files, and subdirectories, since you could sometimes have about 1/2 your disk space free. Every additional 20 slots uses up 5k of disk space, a small price to pay.

So is that it then?

MGT

Upgrade of 256Kb fitted internally by removing the serial number plate on the bottom of the Coupé.

512Kb became the de facto standard quite early on in the machines life.

See also the One Meg external expansion.

MGT

Information originally from Tim Paveley taken from the Sam Coupé Scrapbook

In the last quarter of 1989 MGT launched the Sam Coupé. MGT was already known in the ZX Spectrum world for a range of hardware that they sold. The Sam was their pride and joy, and unfortunately to be their downfall.

The SAM name comes from a working name in the early design phases of ‘Some Amazing Machine’ (or ‘Some Amazing Micro’ or even ‘Spectrum Advanced Machine’ depending on who you talk to) and the ‘Coupé’ was a nickname from two sources: one being an ice cream sundae called the “Ice Cream Coupé” and the other because the machine resembles a fastback car in profile with the feet as the wheels.

The design of the SAM Coupé was produced by the Nick Holland Design Limited in Cardiff with the keys set back from the edge of the casing so as to provide a support for the wrists.

The internal PCB is a T-shape to accommodate the floppy drives, one story of the time is that ‘when they fed in the board shape the CAD program fell over’ although a sad fact of buggy CAD code than the romantic notion of a radical design departure!

This was a time when the 16-bit machines, the Atari ST and the Amiga, were really being to take off. Sales in computers such as the Spectrum was in rapid decline. The Sam was aimed to fill this gap, a powerful 8-bit machine with specs that in cases out performed those of the 16-bit machines, at an 8-bit price. It was hoped that current 8-bit owners, particularly Spectrum owners, would jump on the nicely priced Sam rather than a more expensive 16-bit machine.

See the Sam User Manual and Sam Technical Manual

SD Software

Nev Young

SPI or Sam Parallel Interface was unlike the Comms Interface a bi-directional parallel interface designed by Nev Young and sold through Format Publications.

However only one direction at a time could be accomodated so for full-duplex operation two devices with a SamBus would need to be used.

PDF Manual Scan at www.samcoupe-pro-dos.co.uk

MGT

The Comms Interface was a parallel and RS-232 serial interface box and one of the first peripherals for the Coupé.

The RS-232 interface based on the SCC2691 UART (Universal asynchronous receiver/transmitter) could be driven up to 38,400bps using the Comms Driver sofware supplied although there are issues with the serial hardware that needed to be fixed via a hardware modification, see Hardware Bugs.

The parallel interface utilised a standard 26-way ‘BBC’ to Centronics cable to drive printers although the inferface unlike the SPI was uni-directional.

Information from Andy Gale taken from the Sam Coupé Scrapbook

The SAM allows 8 i/o ports for the comms interface - PRINTL on the expansion port goes low when any of these are being addressed. Ports 232 & 233 are for parallel printer port#1, 234 & 235 for parallel printer port#2, and 236-239 are for the serial interface, which we won’t cover here.

How do you send a byte to the printer? First read port 233 - if bit 0 is set to ‘1’ then the printer is busy and is not ready to accept any data - so keep on testing bit 0 until it becomes logic ‘0’. Next output your byte to port 232 then output 01 to port 233, wait for 1 microsecond and then output 00. Doing this pulls the printer’s /STROBE line low temporarily, telling it that there is a byte for it to print. (/STROBE is fed with an inverted version of bit 0.) For printer port#2, just use ports 234 & 235 in place of 232 & 233 respectively. PRINTL on the expansion port is low whenever an i/o port in the range 232 to 239 is being addressed.

PDF Manual Scan at www.samcoupe-pro-dos.co.uk

ByteDelight

Edwin Blink

Produced from the schematics of the EDDAC the SAMdac is a Stereo 8-bit DAC that plugs into the parallel port on the SAM élite, Comms Interface, External Drive Interface or the SPI.

By connecting to the ‘Audio out/Lightpen’ port the SAMdac allows standard audio from the SAA1099 or beeper to pass through without having to swap speaker connections.

The main application to utilise the SAMdac is the SAM MOD Player

Sinclair Research

See World of Spectrum

LERM

SamTape was a Spectrum Emulator by LERM a maker of ZX Spectrum utilities.