Information wanted LSI computers M-four

[Broosky4]

Recently purchased an LSI computers LTD. M-four and I was wondering if any had information on these machines or the company itself. I've found various info on previous and later machines, unfortunately nothing for the M-Four. I assume I will need to find an original system disk for the M-Four for it to boot.

TIA

 

[SteveH]

Recently purchased an LSI computers LTD. M-four and I was wondering if any had information on these machines or the company itself. I've found various info on previous and later machines, unfortunately nothing for the M-Four. I assume I will need to find an original system disk for the M-Four for it to boot.

TIA

Hi Broosky4,

You’ve probably already found that LSI Computers Ltd were based in Copse Road, St. Johns, Woking, Surrey. Their manufacturing arm, CPU Computers, produced their machines – the LSI M1, M2, M3, M4 and then Octopus (code name M5).

The M4 is a dual CPU machine. The 16 bit 8088 being the primary processor with an 8 bit Z80 under its control. It came with either 128K or 256k RAM and supported two floppy drives (single or double sided 8” or 5.25” floppy drives) or a single floppy drive and a MFM hard drive (usually a Rodime drive of 5, 10, 15 or 20MB capacity controlled by a XEBEC controller). Its O/S was typically CP/M-86/80 (a version of CP/M-86 that would automatically switch in the Z80 when running older 8 bit CP/M programs) or MS-DOS.

The M4 was also rebranded as the CAL-PC for Computer Ancillaries Ltd. The difference being it was in a PC style case with PC style keyboard and external monitor. The CAL-PC motherboard was almost identical to the M4s, the differences being in how it connected to the keyboard and external monitor. The CAL-PC supported two 5.25” floppy drives or a single floppy drive and a MFM hard drive. I’ve used CP/M-86/80, Concurrent CP/M-86/80 version 2.0 and MS-DOS versions 1.25 and 2.11 on the CAL-PC. The M4 and CAL-PC utilities would run on either machine as they first checked the machines signature in the PROM.

There was a review of the LSI-M4 in the April 1983 edition of Personal Computer World, page 166. You can download a PDF copy (unfortunately not OCRed) from the Internet Archive Wayback Machine - https://archive.org/details/PersonalComputerWorld1983-04.

I owned a couple of M4s and several CAL-PCs in the 90s. Sadly they’re long since gone. Some of the CAL-PC firmware documentation and CP/M-86 CBIOS source code I had at the time was sent to Tim Olmstead at the Unofficial CP/M Web Site – now hosted by Gaby Chaudry at http://www.cpm.z80.de/source.html. The following may be of interest:

CALBIOS.ZIP – source code to generate CP/M-86 for the CAL-PC or M4
CALDOC.ZIP – the firmware PROM documentation for the CAL-PC and M4.
CALUTILS.ZIP – a few utilities I wrote to allow the CAL-PC to read other disk formats and to load CP/M-86 from within MS-DOS.

Several years ago (2016 to be precise) I sent some LSI documentation and software to BitSavers.org (look under folder LsiComputers). This was primarily for the LSI-M3 (as I was restoring an M3 at the time - see https://goo.gl/photos/tMza3ootuxB6FYF38 ), the CAL-PC and the LSI-Octopus (I also own an Octopus, but it has been in storage since we moved house a couple of years ago).

Unfortunately for you, I haven’t got an LSI-M4 boot disk. However, I do have a copy of the CP/M-86/80 CPM.SYS file for the M4. Just need to work out how to create a suitable boot disk, i.e. the correct format for your machine (8” or 5.25” and single or double sided) and then create a loader track to load the CPM.SYS file. I’m guessing your machine would have DSDD 8” drives. If that’s the case I could create the correct format (as it’s the same as the M3), then need to create a loader track and add the CPM.SYS file.

And if you hadn’t already guessed, I used to work at LSI Computers - I was at the West Midlands franchise near Birmingham. I was a software developer, back then we were called computer programmers, so worked on the source code for the operating system, Sensible Solution database and a modular accounting package called AXIS MAP.

Anyway, that’s enough from me for now. How about uploading some pics, inside and out of your M4. Last, but not least, if you haven’t already done so, I’d recommend you replace the RIFA capacitors in the PSU.

All the best,
Steve

 

[SteveH]

Hi Broosky4,

It turns out that I do have an M4 disk image that is bootable (see attached) - it contains the Prolog Language, WordStar, some standard M4 utilities (including DISCOPY and FORMAT) and the CP/M-86/80 system file. It is in LSI-M4 5.25" DSDD 400K format and can be written to a diskette using an old DOS based PC with a 5.25" DSDD floppy drive and Dave Dunfield's ImageDisk utility.

If your M4 has 5.25" drives, all well and good. If they are 8", you could temporarily attach some 5.25" drives (IIRC the mainboard has connector sockets for both) and set the relevant jumper switches to indicate DSDD 5.25" drives installed (see the firmware documentation I previously mentioned as it lists the switch settings, but do make a note of their original settings!).

When I get a chance, I'll dig out my stash of 5.25" disks and check what else I may have.

All the best,
Steve

 

[Broosky4]

Thank you for the reply information on this type of computer seems scarce, I apologize how long it has taken to reply a new addition to the family has put any work on hold.

The LSI, when purchased would power on and display random characters. I figured the first place to start would be the RAM chips, After de-soldering the ram chip and testing them, i had found two that had failed. I soldered in some sockets and ordered ram then the LSI was put into storage. recently pulled it back out to find that it no longer displays anything. I've found the reset circuit for the z80 processor isn't operating I've traced the reset line to a PAL1618 chip but not having much knowledge in electronic repair and assuming this chip was configured by LSI themselves. I am unsure how to continue with the repair without knowing the setup of this PAL.

 

[SteveH]

I'm afraid I can't help with the PAL, and unfortunately the M4 schematics that I used to have are long gone. About 7 years ago, when I was restoring my M3, I contacted the engineer who I'd given all my LSI documentation to, but it turned out he had had a big sort out several years prior and had binned it all.

I understand the Centre for Computing History (www.computinghistory.org.uk) in Cambridge has an M4 that is stored away awaiting restoration. You might try contacting them to see if they can help in any way.

There is also an M4 as a museum piece at Axis First (www.axisfirst.co.uk/about/virtualmuseum.asp) - they used to be LSI Computers, then in the early 90s became Systems Axis, and sometime later Axis First. The M4 is, or at least used to be, on their website with other historic computers they used to use.

Let us know how you get on.

EDIT...
Correction to Axis First website address, plus their history states they were originally called Softpac. Obviously my memory isn't what it used to be :-/

 

[paulcpaulc]

Hi folks. My dad worked at LSI Computers when I was a teenager. We are very familar with the M3, M4 and Octopus as he ran the service department. I can ask him any questions if you want to know more info from this critical time in British computing history? He still lives in Bisley, near St Johns where LSI and associated company CPU Computers were based, and I went to school with two of the Execs sons - Fitzpatrick and Johns as I recall.

 

[SteveH]

Hi PaulC,

Welcome to the forum

I don't suppose your dad has any information, technical, advertising, or otherwise for the M3, M4 or Octopus does he? Or even just memories of how these systems developed from ideas through to production? As well as restoring a M3 and owning an Octopus, that still needs restoring, I collect magizine articles and the like whenever I find them. It just so happens I have the following magazine clip from a 1982 edition of Microprocessors and Microsystems magazine that mentions CPU Computers was founded in 1973 by Tom Fitzpatrick and David Johns.

All the best,
Steve