7694 PSL Base Unit

PSL Explorer 1.1 Maybe? PSLDEV1.SYS version 1.1 (9103)
PSL Explorer 0.90 (from WinWorld PC) (User's Guide)
PSL Explorer 1.0 (from "Cathode Ray Dude")
PSL Support Diskette 1.0 (from "Cathode Ray Dude")

PSLDrivers PSLDEV1.SYS 1.00 (8905), 1.1 (9103), 2.00 (9208), 2.10 (9303), 2.20 (9605)
PSLJRC07.C Demo Of Temperature And Distance Probe Software (TURBO C 2.0)
   Thanks to David Ress
DEVICE.EXE Loads and unloads PSLDEV.SYS (TXT file and COM inside)

If you have documentation or actual experience with the PSL, we would like to hear it.


EPROM or Downloadable Microcode?

PSL DOS Device Driver Microcode (PSLDEV1.SYS)
-Version 1.0 - 05/31/89 4,406
-Version 1.1 - 03/21/91 4,912
-Version 2.0 - 08/13/92 7,736
-Version 2.1 - 03/22/93 7,738
-Version 2.2 - 05/04/96 7,789

Why do they refer to this as microcode?

If it was / is microcode, that would make updating the PSL SIMMple-dimple. One thought is that loading microcode during boot would negate the need for upgrading an EPROM, plus overcome any issues with EEPROM or flash cycles.

Silk screening on David Ress' base unit (from 4991) says "80C51". It uses an 87C51, so MAYBE the first PSLs used 80C51s, then the later PSLs used 87C51s.


DOS Device Driver and DEVICE.COM

Normally, CONFIG.SYS loads all device drivers, including the PSL Device Driver PSLDEV1.SYS. When memory is critical, it can be useful to load and unload device drivers dynamically. A small utility named DEVICE.COM is included with PSL Explorer. This utility manages character device drivers such as PSLDEV1.SYS. To use it, modify the PSL.BAT file that invokes PSL Explorer. For example:

  C:
  CD\PSL\EXPLORER
  DEVICE /i PSLDEV1.SYS /N:1    <- added line
  METASHEL /k
  PSLEXPLR.EXE 60 /;
  METASHEL /i
  DEVICE /u                     <- added line

The first invocation of DEVICE loads PSLDEV1.SYS; the second unloads it. The example above must be modified appropriately for your installation: be sure the parameter for PSLDEV1.SYS calls out your COM ports. New installations using PSL Explorer 3 install using DEVICE.COM.

DEVICE.COM is a product of Cinch Industries, Boulder, Colorado.


Serial Port Address

The PSL device driver (PSLDEV1.SYS) uses the IBM PS/2 family communications port standard for the address and interrupts (IRQ).

COM PORT  HEX ADDRESS    IRQ
   1         03F8       4
   2         02F8       3
   3         03E8       3
   4         02E8       3

The cable that comes with PSL is made to connect to a 25-pin D-Shell. If your computer has a 9-pin D-Shell, you can buy a 9-pin to 25-pin adapter. Radio Shack has one with part number 26-209. IBM has one also, with part number 6450242.

"PSL device drivers are available in the Users Guide that allow highly technical customers to program their own applications."

The normal install program sets the device driver statement in CONFIG.SYS as follows.

DEVICE=C:\PSL\PSLDEV1.SYS /n:12 or C:\PSL\EXPLORER\PSLDEV1.SYS /n:12

The /n:12 enables COM ports 1 and 2 to run PSL. If the mouse is connected to COM1 change the device driver statement to:

DEVICE=C:\PSL\PSLDEV1.SYS /n:2 or C:\PSL\EXPLORER\PSLDEV1.SYS /n:2

Now PSL can only be run on COM2.

Base Unit 84F9096 (Base Unit)

The microcomputer “Brain Box” that supervises all PSL operations. The Base Unit allows up to four modules to be attached and provides the interface to the host PC. Low power CMOS electronics and a durable case make it ready for portable operation.

PSL Technical Reference 57F7937 (Base Unit)

PSL Hardware Users Guide 57F7936 (Base Unit)

Base Unit PCB

P87C51 8-bit CHMOS Microcontroller  datasheet 

12.000 MHz xtal
LT1039CN RS232 Driver/Receiver with Shutdown datasheet 

SN74HC138N Decoder Demultiplexer TI Documents   datasheet

SN74HC14N IC HEX Schmitt-Trigger Inverter  TI Documents   datasheet

P87C51 Block Diagram

P87C51 Pin-Out

On-Chip Oscillator

"To use the on-chip oscillator, connect a crystal or ceramic resonator between the XTALI and XTAL2 pins of the microcontroller, and capacitors to ground"

See Y1, C3 and C4? Now it makes sense...

Looks like most of the secret sauce is in the 87C51. Look at the -5.0v regulator. Nice heat sink. See the electrolytic cap pair by each module port?  Made 4991. No corrosion.

Note the 14 conductor edge cards on the left. The upper three traces on each port look beefier, power?

Spring loaded port covers? Makes me wonder if this isn't like RI/RO ports... But this is an 8 bit CPU, these ports are enough for serial communication.

Looks like the grey plastic sides clip onto the side ports.

When my hardware guide arrives, I'll be scanning...


Power Supply 57F7931 (Base Unit)

115 VAC wall mounted, UL listed supply that powers the entire PSL system. Output is 8 volts DC at 1 ampere.

Steed Magnet Products Enterprise Co., Ltd. catalog Page 92, physical

Model F5-DC81A-F2
F5 - 120v input, 3 prong (dummy ground prong...) Steed case 48
DC - rectified and filtered DC output
81A - 8 (v) at 1A
F2 - DC plug I.D. x O.D. x L F2 2.5x5.5x12

Note: Center Positive!

PSL Battery Module PSL7200
The PSL Battery Module connects to one of the Base Unit Module Ports and powers the Base Unit, Modules and Probes for 8 to 24 hours. This allows PSL to be used with laptop or palmtop computers in the field, providing a completely portable system. Rechargeable batteries with a built-in charger make it easy to power up.

Simply plug the Battery Module into any one of the four PSL module ports. Recharge by connecting the PSL power supply to the charging jack on the rear of the Battery Module.
High capacity nickel metal hydride rechargeable batteries.
Built in charging circuit with automatic shutoff.
Completely overload and thermally protected.
Can be used as a backup supply for PSL for long experiments.
Multiple Battery Modules can be used together to extend the total running time.
Auxiliary power jack can be used to power the PSL Laser Source or other 5 volt devices.

The PSL Battery Module uses the Base Unit AC power supply for charging. It is completely overload and over-temperature protected.

    Battery Type: 1800 milliamp hour Nickel Metal Hydride
    System Power: 7.2 volts DC @ 3 amperes
    Auxiliary Power Jack: 5 volts DC @ 1.25 amperes

Communications Cable 57F7932 (Base Unit)

A 1.5 meter shielded RS-232 cable that attaches Base Unit to Host PC’s Serial Port .
Note: "Straight through" wired. Do NOT use a "Null Modem" cable!

Make sure your communications cable between the computer is not a "null modem" cable. These cables are not compatible with PSL. PSL will not run with a null modem. There are also null modem 9-pin to 25-pin adapters that won't work. The rule is "No null modem cables or null modem adapters". To determine if a cable is a null modem cable, assuming both the cable's box and the cable don't say NULL, you will need a continuity tester of some kind. Remove any adapters or hardware attached to the cable in question.

25-pin connectors >OR< 9-pin connectors at both ends:

On a "straight through" serial cable, pin 2 is connected to pin 2 at both ends. On a null modem cable, pin 2 is connected to pin 3 at the other end. See illustration for pin numbers.

25-pin connector at one end, and a 9-pin connector at the other end:
On a "straight through" serial cable, pin 2 is connected to pin 3 at the other end, and a null modem cable would have pin 2 connected to pin 2. See illustration for pin numbers.

Content created and/or collected by:
Louis Ohland, Peter Wendt, William Walsh, David Beem, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 23 Oct 2021 - Changes & Credits | Legal Info & Contact