3. System Installation

3.1 Parts List

To produce a basic PC-compatible STEbus system, the following items are needed:

One system case

One STEbus terminated backplane

One mains lead

One Power supply rated to:

+5V 3.0 A (plus 0.54 A for each disk drive)
±12V 50 mA (for RS232 drivers if SPCOM present)
+12V 0.38 A (for each disk drive)

One SCPC88 processor board (supplied with PC BIOS ROM)

One SPDC disk controller board

One disk drive, double sided double density 40-track

Example power requirements for type FD55BV:

+5V ±5% typical: 0.22A max: 0.54A
+12V ±5% typical: 0.30A max: 0.38A

One 34-way disk drive connector ribbon cable

One 10-way ribbon cable (supplied with SPDC to connect it to the SPC88)

One SPEGA board (supplied with EGA BIOS ROM)

One video monitor, from one of the following types:

Monochrome IBM 3270
Monochrome composite video
CGA (standard RGB TTL)
EGA monitor
Multisync

One appropriate cable for the above (phono connector for composite video, way D-type for others)

One PC-compatible keyboard

One speaker (optional)

If you have ordered a complete system from Arcom and any of these items are missing, then contact Arcom immediately.

3.2. Boot disks.

The SCPC system will run all PC software, and accepts boot disks from PCs or compatibles.

3.3. Links

For the SCPC88 make only the following links: LK1C, LK6, LK7, LK8, LK9.

For the SPEGA make only the following links: LK1A, LK1E, LK3B.

For the SPDC there are no links. The SPDC only needs connecting to the SCPC88 via the short 10-way ribbon cable supplied.

For type FD55V disk drives, make links DS0 or DS1 (for drive 0 or 1, respectively), U1, U2, XT (pin 34 open circuit) and FG (frame grounded). These links are labelled and visible from the underside of the drive.

Link settings for STEbus memory boards will be unique to a particular board, to satisfy the requirements described in Section 3.7. For an SDRAM board fully populated with 256Kbit DRAM chips, the correct links are:

LK1-2A	LK2A
LK1-2B	LK3C
LK1-2C

3.4. System assembly

Fix the PSU, disk drives, and STEbus backplane to the system case. Wire the PSU to the backplane and disk drives using heavy duty wire. Make the links specified above.

Plug the SCPC88, SPDC and SPEGA into the backplane. Connect the SCPC88 (PL4) to the SPDC (PL2) using the 10-way ribbon cable. Connect the SPDC (PL3) to the disk drives using the 34-way ribbon cable. Connect the keyboard to SCPC88 connector PL3. Connect the SPEGA to the monitor using the appropriate cable.

Apply power through the mains lead.

Insert a PC system boot disk in drive.

3.5. Booting the system

On power-up, the screen will be initially be blank, as the system performs its self-check programs. A sign-on message appears (reporting the status of the various peripherals) which will look something like this:

*** ARCOM CONTROL SYSTEMS LTD PC BIOS V1 ISS 1 ***

RAMSIZE 256k

NUMBER OF DISK DRIVES 1

NUMBER OF PRINTER INTERFACES = 0

NUMBER OF SERIAL INTERFACES = 0

8087 NOT INSTALLED

VIDEO MEMORY AO000H TO BEFFFH

EGA BIOS     C0000H TO C3FFFH

KEYBOARD INSTALLED

INSERT SYSTEM DISK  PRESS RETURN

If a boot disk is already inserted in drive A, the operating system will be booted. Otherwise, the disk should be inserted and RETURN pressed if necessary. Once the the operating system has booted, it prompts for the current time and date (RETURN can be pressed to enter dummy values). Then the A: prompt appears, and all the usual DOS commands are available.

Current date is Tue 1-01-1980

Enter new date (mm-dd-yy) :

Current time is 0:00:14.00

Enter new time :

Microsoft (R) MS-DOS (R) Version 3.20

(C) Copyright Microsoft Corp 1981-1986

A:>

If a non-bootable disk is inserted by mistake, an appropriate error message is displayed. The correct disk should be inserted and RETURN pressed, which will cause the BIOS to retry booting. If this fails, then press CTRL-ALT-DEL, which is a more thorough boot be cause it re-reads the system boot track.

3.6. Memory expansion.

The SCPC88 has 256K of (on-board) RAM as standard. This can be expanded to 640K (the maximum DOS will recognise) by the addition of an STE memory board to the system. This would normally be a 512K SDRAM board, jumpered to start at STEbus address 20000H (but will only be accessed above the SCPC88 onboard DRAM, at 40000H. For this start address, the SDRAM board must be populated with sixteen 256-kilobit DRAM chips, and the following links must be jumpered as described in Section 3.3. Links. Once the board has been plugged into the STEbus, the BIOS signon message should report the increased memory size when booting up:

3.7. Changing processor clock speed.

The SCPC88 processor board will initially be running at 4.77 MHz. The SCPC88 can be made to run 50% faster by changing the clock frequency to 7.16 MHz.

This can be done from from DEBUG using the command:

	o63, 47 (if 8087 fitted)

or

	o63, 45 (if 8087 not fitted)

or from C by running the program TURBO.C listed below:

main() {
	printf"Setting high-speed mode");
	if	(peekb(0x410,0) & 2)	/* Test bit 1 of RAM location 0:410 */
	{
		printf(" (8087 fitted).");	/* Bit set: 8087 */
		outportb(0x63, 0x47);
	}
	else	outportb(0x63, 0x47);
}

In AB88 8088 BASIC compiler, this would be:

	OUT &63, 47		: REM if 8087 fitted

or

	OUT &63, 45		: REM if 8087 not fitted