Blinky

Hardware and sample guru.

Persona

Edwin Blink

The ATOM Hard Disc interface is an internal IDE hard disc interface that fits to the Sam Drive connector.

The interface consists of a 16 to 8 bit bus converter, address decoder and a bus stabiliser to make the rather slow Z80 bus interface with the fast IDE bus.

The interface takes it power from the SAM. A single 2 inch drive which consumes not more than 500 mA can also be powered by SAM. But Other drives must be powered by a separate power supply.

See Edwin’s ATOM Page for full details.

The ATOM is merely the IDE interface, the operating system to drive it is B-DOS.

This is the second IDE interface in wide use, the fist being Nev Youngs’s SD IDE interface that ran HDOS.

A popular media to use rather than a full IDE drive is a Compact Flash (CF) card which prompted the development of the Atom-Lite.

Graham Burtenshaw

The Load Save switch was a solution to excessive wear and tear on the tape connector on casette players.

Becuase the Coupé had a single tape socket (unlike the ZX Spectrum’s MIC and EAR) when saving a program to tape you had to swap the lead from the EAR to the MIC connector on the tape player.

The Load/Save Switch was a box with two flyleads going to the MIC and EAR on the tape player and a switch to allow you to select either and this save wear on the tape player sockets.

Public Domain

Steve Taylor

A superb interrupt driven pointer utility to work with the Mouse Interface as well as supporting the keyboard cursor keys making it easy for programs to support both input methods.

Used extensively for PD work, especially by Dan Dooré.

Released 10/12/93

SamCo

The Official Sam Mouse interface used and Atari ST type Mouse as opposed to the then more common serial mouse.

The mouse driver code once loaded would populate the variables XMOUSE, YMOUSE and BUTTON that could be read by the user.

The disc contains a Basic demonstration, a (poorly) modified version of Flash! and a ‘Slidy’ game by Richard Robinson that was modified by Colin MacDonald to use the Sam Mouse.

Many games such as Lemmings and Batz 'n Balls were best played with the mouse and for Basic users Steve Taylor’s Mouse Driver 2.0 offered an interrupt-driven pointed system.

Persona

The Three-Up is a 3 port EuroConnector expansion similar to the Two-Up and SamBus but without the real time clock.

Features two vertical and one horizontal connector, an auxillery PSU jack and a headphone/speaker jack.

Author of Sam Paint and Momentum and produced of hardware like the Load Save Switch.

Founder and editor of Enceladus magazine.

Known Hardware Issues and Bugs

• The limit of 128 colour palette as opposed to the desired 256 was allegedly due to not having enough spare physical pins on the ASIC’s die to accommodate it. As it stands there are two pins for each colour (Red, Green and Blue) and a BRIGHT output meaning that there are three bits for each colour, top two bits as per the colour pins output and the least significant bit set by the BRIGHT setting.
  
• When the reset button is pressed the SAA1099 sound chip is not reset so notes being played will continue.
  
• The ASIC does not send an 8Mhz reset signal to the Sam Drive disc controllers when the Reset button is pressed which can cause corruption to a floppy disc left in the drive - hardware fix is the DPU by Edwin Blink
  
• The NMI button is not de-bounced causing multiple NMI’s to be generated - hardware fix is the NMI Debounce by Edwin Blink. The Messenger included a separate NMI board to get around this issue.
  
• The MIDI ports allegedly do not work as explained by Steve Nutting in Fred 2
  
• There is a lot of reflection on the screen when using an RGB cable, there is a Reflection fix from Colin Piggot
  
• The serial port on the Comms Interface has a hardware bug as listed in Format Vol.5 No.8 where you get transmission errors after 100-200 characters regardless of baud rate. This is due to an electrical supply issue in the board which needs smoothing. To fix, solder a fat tantulum capacitor between the 0v and +5v across the supply lines near R3.
  
• The Sam Mouse interface can also be erratic due to the same power issue - the HCT chips in it don’t like the SAM’s glitchy supply so shove a couple of the biggest electrolytic capacitors you can find and a tantalum capacitor inside your SAM across the +5v and 0v rails. from Simon Cooke on the Sam Users Mailing List October 1994.

See also ROM bugs

MGT

Bruce Gordon

The ASIC (Application Specific Integrated Circuit) was the equivelent of the ULA (Uncommited Logic Array) in the ZX Spectrum, a multi-purpose chip to provide functions that would normally require extra hardware and hence extra cost.

The ASIC was also responsible for some Hardware Bugs and limitations.

There also exist 40 prototype Golden ASICs.

SamCo

SamTek

Very simple - One Megabyte of memory on an expansion card.

The memory could not be accessed from Basic but could be paged in at machine code level and was most useful to use as a RAM Disc with MasterDOS.

Most users with the One Meg also had a SamBus or a Two-up/Three-up interface expansion unit.

On the circuit board there is a jumper connection (bottom left above the capacitor) to allow a one from four position selection (which is factory set to position four). This enables up to four 1 Mb External Interfaces to be connected together giving a possible total memory capability of 4.5 Megabytes of RAM (4,718,592 bytes)

A few products utilised the extra memory such as E-Copier by Chris White and Sam Paint.

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

Schematics